DEPARTMEMT OF LAIDS, FORESTS, AND WATER RESOURCESa100.gov.bc.ca/appsdata/acat/documents/r4438/270_114142750598… · with the drilling bcing done by Big Indian Drilling Company Limited

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DEPARTMEMT OF LAIDS, FORESTS, AND WATER RESOURCES WATER RESOIJRCES SERVICE

It. COMRNULHT ff l H E s R o y u I C E O T B R m w C ~

;CANADA- ERI TISH C OLUbTBI.4 OKANAGAN BAS IN AGREEMENT

A HYDROGEOLOGICAL ST.TXDY ' ,

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WATER ImTIGATIONS BRANCH BRITISH COLUMBIA WATER RESOURCES SERVICE

DEPARTMENT OF LANDS, FORESTS AND GIATER RESOURCES PARLIAMENT BUILDINGS

VICTORIA, BRITISH COLUMBIA

R. A . W i l l i a m s , Ministxr - WATER RESOURCES SERVICE V. Raudsepp, Deputy Minister

WATER INVESTIGATIONS BRANCH B O E. Marr, Chief Engineer

CANADA-BRITISH COLUMBIA OKANAGAN BASIN AGREEMENT

A HMRI)GEOIQGICAL STUDY OF THE OKANAGAN RIVER BASIN

TASKS 38, 39, 40 & 41

F i l e Nos: 0249723 0281 792-'

September 1972

1 E. Gordon Le Breton, P. Eng. S m i o r G eo log ica l Engineer

CANADA-BRITISH COLUMBIA OKANAGAN BASIN AGREEMENT

TECHNICAL SUPPLENENT I1 To F I N A L REPORT

A HYDROGEDLOGICAL STUDY OF

THE OKANAGAN RIVER BASIN - -

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E. Gordon Le Breton Water Investigations Branch

ui t h

Hydrogeological reconnaissance reports on Vase- Creek and Vernon Creek Sub-basins

bY

E. C, Halstead Inland Waters Branch

Department of the Environment

Penticton Creek and Pearson Creek Sub-basins

bY

P. L. Hall Water Investigations Branch

Lambly Creek c:id Greata Creek Sub-basins

bY

E, Gordon Le Breton Water Investigations Branch

. u w . .

. .

CANAL)A-BRITISII COLUblBIA OKAI'!A(;AN BASIN STU:DY

TECIINICAL SUPPLEPIENT TI

GROUNDWATER STUDIES I N THE OMNAGAN R I V E R BASIN

E. Gordon Le Brcton Ground w a t e r D i v i s ion

Watex Investigations Branch

Water Rcsources Scrvice

Department o f Lands; Forests and Natcr Rcsources

for

Ikccmbcr, 1972

ABSTRACT

,.

0

The o b j e c t i v e o f t h i s groundwater s tudy was t o de te rmine o r d e r of

magnitude f i g u r e s of t h e e x t e n t , y i e l d and r e c h a r g e r a t e s of groundi;ater t o

a q u i f e r s , p a r t i c u l a r l y i n t h e North Okanagan, and t o de te rmine t h e sou rces

of r echa rge t o t h e s e a q u i f e r s .

I t i s cons ide red t h e main source of r e c h a r g e i s d i r e c t l y f r o n p r e c i p -

i t a t i o n , though some groundwater i n f l o w may occur from t h e a d j a c e n t Salmon

River Val ley . The q u a n t i t y of ground\sater :€low moving towards Okanzgan Lake

i s e s t i m a t e d t o range between 3-1/3 and 6 cfs.

Though sone a q u i f e r u n i t s may ex tend throughout much of t h e n o r t h

end of t h e Okanagan Va l l ey , well y i e l d s are commonly e s t i m a t e d t o be less

t h a n 250 igpm f ron pumping dep ths of abou t 200 f e e t . Only v e r y l o c a l l y a r e

we l l y i e l d s expcc ted t o range between 500 t o 1,000 i g p f ron t h e saine pump-

i n g d e p t h s . Such h i g h y i e l d s a re known t o b e a p o s s i b i l i t y t o t h e sou th of

Armstrong, and s i m i l a r f zvourab le s i t e s may be found i n t h e O'Keefe \ ' a l ley

and a l s o near Enderby.

,

I.

I1 . 111.

I V

Summary R e n o r t .

COXTEMTS

INT3ODUCTION

METHODS 8: SCOPE

RESULTS & CONCLUSIONS

1. Geology

2. Groundwater Flow from Adjacent Basins

3. Aquifers in the Surf'icial Deposits

4. Water-Well Yields

se Groundwater Potential ,

6. Water-Well Costs

7. Groundwater Quality

8. Sub-basin Groundwater Studies

GLOSSA3Y OF TSiiMS

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.--- i SUbBfiRY REPORT

INTRODUCTION.

Thc groundwatcr program d i scusscd h e r e i n , i s p a r t of a cornprehcnsive s tudy o f t h e watcr r e s o u r c c s o f t h e Okanagan Basin b e i n g conducted under t h e Canada-Br i t i sh Columbia Okanagan Basi.n Agreement s i g n e d i n October , 1969.

The o b j e c t i v e s o f t h e groundwatcr i n v e s t i g a t i o n s were t o t r y t o d e t e r - mine the g r o u n d ~ ~ t e r flow i n t o and from Okanagan Lake, t h e groundwatcr p o t e n t i a l o f t h e v a l l e y - € i l l d e p o s i t s , and t o dctermine t h e groundwatcr component o f s i x s e l c c t c d sub-bas ins t o more f u l l y unders tand t h e hy- d r o l o g i c budget of t h e Okanagan R ivc r Basin.

The work compr is ing t h i s r e p o r t was broken down i n t o s e v e r a l t a s k s -38, 39, 40, 41, and 47 .

Task 38, a seismic program, was d i r e c t e d by R . M. Lundberg, P . Eng., Calgary , A l b e r t a , w i t h the a c t u a l seismic work b e i n g done by Geophysi- cal S e r v i c e s Inco rpora t ed .

. .

Task 39 i n v o l v e d f i e l d mapping o f s i x sub-bas ins . Th i s work i s covered i n r e p o r t s w r i t t e n by E . C . H a l s t e a d , Research S c i e n t i s t , Hydrologic Sc iences D i v i s i o n , In l and Waters Branch, Department o f t h e Environment, and by P. L . Hall and E . G . Le .Bre ton , h y d r o g e o l o g i s t s , Groundwater D iv i s ion , lJater I n v e s t i g a t i o n s Branch, B r i t i s h Columbia Water Resources S e r v i ce.

Task 40 comprised deep and i n t e r m e d i a t e dept.h t e s t - h o l e d r i l l i n g and . well comple t ion . The former was t h e d i r e c t r e s p o n s i b i l i t y o f D r . J . C . Foweraker, C h i c f , Groundwater D i v i s i o n , Water I n v e s t i g a t i o n s Branch, wi th t h e f i e l d yrograin b e i n g conducted by E . L iv ings ton , P . Eng. , Vancouvcr and t h e d r i l l i n g b e i n g done by Idardcan D r i l l i n g Company Ltd. Thc i n t e r m e d i a t e deep h o l c d r i l l i n g was s u p e r v i s e d by E . G. Le Breton wi th the d r i l l i n g b c i n g done by Big Ind ian D r i l l i n g Company Limited. \

Task 41, c o n s i s t e d of c l c a n i n g , dcvc loping and t c s t pumping. Th i s t a s k was s u p e r v i s c d by E. G . Le 1;rcton and t h c work was c a r r i c d ou t by J . Moore, Osoyoos T i l e Works and I h t e r Wells .

Task 47 invo lvcd c v a l u n t i o n of v a r i o u s t a s k S jndjngs and ] ~ r c v i o u s l y ob- t a incd inforni:itj on, r e p o r t wri t in{;, and in tc i*pi -c t ing t h e v a r i o u s r c p o r t s i n t o the p r c s c n t v o l u ~ ; ~ ~ (F igurc A) .

2

LIETI-IODS AND SCOPE

The groundwater programs c o n s i s t e d oil t h e fo l lowing i n d i v i d u a l s t u d i e s .

Tasks 38 39 40

4 1 47 Ground\catcr Evalua t ion

S e l e c t e d Sub-Basin Hydro-Geologic Surfacc I n v e s t i g a t i o n Sc ismic Exp lo ra t ion of Groundwater Resources Groundwater Resourcc Exp lo ra t ion ; Blain Va l l ey Deep Rotary T e s t Holcs 1nstruincnt .a t ion and T e s t i n g o f Dccp Idells

The purpose of t h e seismic. work (Task 3 9 ) , was t o o b t a i n in fo rma t ion on t h e depth t o bedrock a c r o s s several s e c t i o n s i n t h e Okanagan and O'Keefe Va l l cys , t o t r y t o determine t h e n a t u r e o f t h e v a l l e y - f i l l d e p o s i t s , t o h e l p t o reduce t h e number of t e s t holes requfircd t o l o c a t e t h e t h i c k e s t s e c t i o n of overburden , and t o h e l p s e l ec t t h e t y p e o f d r i l l i n g equipment r e q u i r e d t o accomplish t e s t d r i l l i n g .

The seismic su rvey proved t o b e a very v a l u a b l e t echn ique f o r enab l ing t h e Groundwater D i v i s i o n t o p i c k t h e deepes t p a r t s of t h e v a l l e y f o r t e s t - h o l e d r i l l i n g . 6 seismic p r o f i l e s and were poor on ly c l o s e t o t h e v a l l e y walls.

Task 40 c o n s i s t e d of deep and i n t e r m e d i a t e depth r o t a r y - t e s t d r i l l i n g programs. t o d r i l l th rough t h e overburden t o t h e bedrock , and t o p rov ide : i n fo r - mation on t h e t y p e , t h i c k n e s s and c o n t i n u i t y o f t h e v a l l e y - f i l l depos- i t s , t o s t u d y g e a l o g i c s t r u c t u r e o f the main v a l l e y , and a l s o t o check on t h e va lue of p r e l i m i n a r y seismic e x p l o r a t i o n . The r e s u l t s could be used as an i n d i c a t o r f o r a s s e s s i n g groundwatcr r c s o u x e s and f o r making t h e o x t i c a l estimates o f groundwater flow towards Okanagan Lake. a d d i t i o n t o t h e above p l m n c d o b j e c t i v e s , t h e t e s t h o l e s w,ere l e f t ca sed t o be used as o b s e r v a t i o n wells.

"lie o b j e c t i v e of Task 41 was t o o b t a i n suppleincntary d a t a concern ing groundwater q u a l i t y and I - c l i a b l e estimntcs o f t h e ra tes a t which water can be produccd from a s i n g l e well o r from a well f i . c ld e x t c n d j n g ovcr a relatively l i m i t e d arca. The d a t a c o l l c c t e d could be uscd t o s e l e c t p o s s i b l e f u t u r e t e s t - p r o d u c t i o n \veil. s i t e s . I t \\'as a l so unders tood t h a t sonic infor111atj.on obta incd i n addi . t j on t o the above-incnti oncd object . i .vc , t h c d e r i v a t i o n o f permcabi l i t y (hydr3ul i c conduct. ivi . ty) va lues f o r t h c aqui.fers i n which t h e t e s t h o l c s \$cw completcd, \mulrl be uscd t o inakc c n l c u l a t i o n s of r a t c s of gi-oundisatcr f l m s i n cubj c f c c t p e r sccond. 41.

R e s u l t s proved t o be q u i t e good a c r o s s much o f t h e

. .

The purpose of t h e t e s t h o l e d r i l l i n g jlas i n i t i a l l y des igned

I n

Such inforniat . ion was secondary ' t o tlfc mnin ob j c c t i o i l o f Task

(-0 . ..

:.

3

and complcted f o r obse rva t ion -wc l l purposes. 39, 40 and 4 1 comhincd wi th \ iork from p rcv ious ycai-s havc! enablcd a hydrogeologjca l st:ii;y t o be madc of t h c a r c a .

I of thc s tudy have been p r e s c n t c d on a map and c r o s s s e c t i o n s showing geology, groundwater movement, and groundwater q u a l i t y o f a q u i f e r s i n t h e s tudy a r e a .

The r e s u l t s from Tasks

Somc o f t h e main ‘a spec t s

The o b j e c t o f Task 38, was t o de te rmine i.f t h e groundvatcr coniponcnt of the sub-bas ins was of s u f f i c i e n t volume t o war ran t t h c e x p e n d i t u ~ e o f more time and funds t o p rov ide as complcte a s p o s s i b l c an asscssmcnt of i t s ‘con t r ibu t ion t o t h e h y d r o l o g i c regime.

Task 47 comprised an e v a l u a t i o n o f t h e r e s u l t s o f work conducted under the s t u y d agreement and i n t e g r a t i o n of t h e f i n d i n g s wi th prevj ous work.

4

RESULTS. AND CON C LUS I ONS

Gcr:.ral Gcology -. .

Tlic O k a n a g ; ~ Basin i n Canada i n c l u d c s a drai i iagc area o f some 3,000 squa re miles. Mountains rimming t h e b a s i n reach e l e v a t i o n s o f 7,372 fee t a t Apex Mountain on t h e west s i d e and 7,,633 fee t a t Big Iiliite Mount.ain on t h e eas t s i d e , I ts v a l l e y f l - o r 1 i .es .a t an e l e v a t i o n of 1,800 fee t n e a r Enderby and grades t o 900 f e e t above s c a - l e v e l a t Osoyoos Lake wherc t h e b a s i n r e a c h e s t h e I n t e r n a t i o n a l Boundary. The v a l l e y f l o o r r anges i n width from 2 t o 10 miles and i s l a r g e l y occupied by a systciii of l a k e s and t h e Okanagan River .

The Okanagan Basin is u n d e r l a i n by a d i v e r s i t y o f rocks . si de h a r d , r e s i s t a n t g e n t l y d i p p i n g metamoqdiic rocks i n c l u d i n g g n e i s s , a L l l A b ~ , qucirtz i ie , caicareous g n e i s s and marbie p r e s e n t pronounccd g e n t l e s l o p c s due t o d i f f e r e n t i a l weather ing . l a i n by two groups of rocks ; one n o r t h o f Vernon i n c l u d e s most ly s c h i s t s and q u a r t z i t e s wi th g e n t l e rounded s:lopes and t h e sou th group i n c l u d e a r g i l l i t e s , a n d e s i t e lavas and l imes tone exposed i n more rugged r e l i e f . In p l a c e s t h e s e rocks are covered by f l a t l y i n g o r g e n t l y d i p - p i n g l a v a s . complex of c rys t a l l i ne rocks i s l i m i t e d t o i n t e r c o n n e c t e d f rac ture and f a u l t systems. I t i s r e a l i z e d t h a t mzjor f u a l t zones will p rov ide con- d u i t s f o r t h e movement of groundwater b u t t h c p r e s e n t a t i o n h e r e i s concerned l a r g e l y w i t h aqui fers be long ing t o t h e unconso l ida t ed s u r f i c i a l d e p o s i t s . Th reconnaissance s t u d i e s c a r r i c d o u t - i n s e l e c t e d sub- b a s i n s gave some c o n s i d e r a t i o n t o t h e movement o f groundwater i n bed-, rock f r a c t u r e systems and t h c over1yin.g unconso l ida t ed d e p o s i t s com- p r i s i n g l o c a l flow system a d j a c e n t t o streams and i t \vas concluded t h a t t h e s e l o c a l systems could p r o v i d e a b a s e flow i n t h e o r d e r o f 3 cfs.

On t h e e a s t

- -3.: -4 .

The west s i d e i s under-

In g e n e r a l , s t o r a g e and movement o f groundwater i n t h i s

The unconso l ida t ed s u r f i c i a l d e 2 o s i t s c o n s i s t o f c l a y , s i l t , g r a v e l , sand and mixtures o f t h e s e t h a t o v e r l i e t h e bedrock. They are o f g l a c i a l o r i g i n and t h e i r d e p o s i t i o n i s r e l a t e d t o t h e g l a c i a l i ce t h a t occupied t h c v a l l e y o r t o t h e meltwaters t h a t i s s u e d thcre€rom dur ing t h e was t ing s t a g e s of t h e ice . v a l l e y may have rcachcd c l e v a t i o n s as much a s 7,200 f ee t it l e f t only a t h i n b l a n k e t of unconsol ida ted m a t c r i a l s a t t h e h i g h e r c l c v a t i o n s .

Although t h c g l a c i a l i c e f i l l i n g t h e

F igure 1, i n thc n o r t h end o f t h e Okanagan R ive r Bas in , shows a r c a s of m a i n l y bedrock abovc 2,500 f e e t o r probably t h i n unconso l ida t ed dc- p o s i t s abovc about. 1,500 f e e t . Below c l e v n t i o n s of 1,500 fcc t and p re - dominantly on t h e cast . s i d c of the ' v a l l c y , occu r numerous fan o f f an - d e l t a deposit.^ o f g r a v e l and sand . s i d c of tlic iliain Oknn~tgnn Val l cy a r c found a s s o c i n t c d n1:rnst cn t i r cZy \ ~ i . t h t h c O'Kcefc t r ibut ; i r ) r v a l l c y and t h c ~ O N ~ J : p a r t of Dcep C1.cek Val- l ey LeIfiic i i . e~ricrs -ihe m:i in v a i l c y . found a t 0 3 : n c a r t h c suyfacc a r c coimuonly s i l t and soi:ic c l a y .

Coarsc s a n d and ravel on t h c \:rest.

.... iiie dcposirs o f tiic main v a l l e y

5

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0

The t h i c k n c s s of tlic v a l l e y f i l l i s knorm i n t h e n o r t h end of t h e Val- Icy where sc i s in i c p r o f i l e s have been run across t h e Okanagnn Va l l cy t o dctcr injnc t h c p o s i t i o n and shtlpe o f t h e bcdrock benca th t'he v a l l e y f l o o r by F c d c r a l and P r o v i n c i a l Agencies. The lowest c l c v a t i o n was found t o b c sou th of Armstrong wliere t h e bec1:rock f l o o r of t h c v a l l c y i s about 600 f c e t below sea l e v e l . The thickness of t.he v a l l c y f i l l ncai- Armstrong j.s t h e r f o r e about 1 , 800 f e e t . a v a i l a l i l c from d r i l l r eco rds and logs i n d i c a t e s t h a t t h e s t r a t i g r a p h y of t h i s thi .ck f i l l j s complex i n d e t a i l . A t t h i s p o i n t i n t h c desc1.i.p- t i o n o f t h e s u r f i c i a l d e p o s i t s a t t e n t i o n i s drawn t o t h e no r th - sou th (Figuyc I) and eas t -wes t (F igure 1) c r o s s s e c t i o n s f o r t h e n o r t h 'end of t h e main v a l l e y . An important r e su l t o f t h e t e s t d r i l l i n g conducted widcr Task 40 , i s t h e r e g i o n a l p i c t u r e which can be cons t . ruc ted of t h e s u r f i c i a l d e p o s i t s o f the main v a l l e y . Thcse can b e di-vided i n t o two par ts -- lower and upper p a r t s . The lower p a r t o f t h e sediments shows an a l t e r n a t i n g sequcnce of tj.11, c l a y and s i l t , sand and g r a v e l zones divi-ded i n t o u n i t s A t o F . This sequence ranges from about 300 f ee t t h i c k i n t h c n o r t h a t C 4 3 TH5 t o about 750 f e e t t h i c k i n t h e sou th a t C42 THl. The till zones range from about 40 t o 100 f e e t t h i c k ; s i l t , sand and g r a v e l zones a re about 80 t o 220 f e e t t h i c k , and a c l a y - s i l t zone i s about. 100 f e e t t h i c k . Facies changes w i t h i n t h e s e l a y e r s may be due t o non-depos i t ion i n some p a r t s of t h e v a l l e y , o r t o removal and subscquent repla.cement by l a t c r g l a c i a t . i o n s . t h e s e s i l t , sand and g rave l zones i s t h e one i n which most of t h e deep t e s t ho le s were conipleted. as obse rva t ion wells. The u n i t s A t o F have been denoted i n ascending o r d e r .

Thc l i t h o l o g ~ c i n f o r m t i o n

The uppermost o f '

Over ly ing t h e success ion o f t i l l s and sands ., and compris ing t h c upper p a r t of t h e main v a l l e y d e p o s i t s , i s 500 t o 1,000 f e e t of sedi incnts t h a t are mainly s i l t . Therc a r e some sand beds i n t h c upper p a r t o f t h e sequence , and of p a r t i c u l a r importance t o t h i s s tudy a r e t h c t h i c k sands o c c u r r i n g i n t h e Flaid Creck arca soutli of Arinstrong. i n the upper p a r t of t h e s u r f i c i a l d e p o s j t s a re commonly f i n c t o medium- g r a i n e d , a n g u l a r sands .

The sands

Cons iderable l o c a l v a r i a t i o n s arc an t i c ipa . tod w i t h i n t h c uppcr p a r t of t.he surfj c i a 1 d e p o s j t s . Local dcposi . ts o f gravel and s a n d on t h e e a s t sick of t h c v a l l e y a r c attributed t o me1 t w a t e r s from t r j . b u t a r y val l cys , and sands on tha v c s t si .de o f t h e blnid Crc?c'k c r o s s scc t io r i may h;n:c bcen dcrivctl i n a s s o c i a t i o n w i t h 1nc1.twaters dischargi .ng t o t h e sou th froin Ilccp Creek (1;igm-c 1). v a l l c y t l i i ckcn ing of b o t h the uj>pc:r and Ioiicr p a r t s of t h e va l lcy- f - i 11

I t may a l s o bc obscrved t ? i n t t he re j s do\~ii-

dcpos i t s .

a

0

6

~ a l ~ c y , 11ut j t i s u n ~ i ~ ; c l y t h a i t h e r e i s groundwatcr flow from t ~ i c Sliuswap Va l l ey .

Froin undcrf low c a l c u l a t i o n s a t o t a l r a t e f o r p-oundwatcr niovcment t o - \sards Oknnagan Lake o f about 3 1/3 cfs (2370 a c f t l y r ) 113s bcen d e t e r - mined. Viis i j gurc seciiis rcasonab1c compared t o a r echa rge ra te of 6 c f s (4350 a c € t / y r ) froin 1 inch o f p r c c i p j t , i t j o n r cach ing t h e watcr t a b l c o v c r a rechargc a r e a c s t ima ted as 80 squa re milcs.

Groundwater s t u d i c s w i t l i i i i the main v a l l c y have becn conf j ned c n t i r c l y t o t h e n o r t h e n d , and no s t u d i c s have becn c a r r i c d o u t wi th r e g a r d t o gi-oundwater 1-cturn flow from i r r i g a t i o n , n o r has any work becn clone on ~ h i c h t o base e s t i m a t e s of. groundwater flow a t t h e sou th end of Okana- gan Lakc. w i t h i n t h e b a s i n i s sho\\!n i n F igure B.

A g c n e r a l i z c d and schcinatj c i l l u s t r a t i o n o f groundwatcr flow

Aqui fers i n t h e S u r f j c i a 1 Deposits

The s u r f i c a l d e p o s i t s mainly s i l t and f i n e - g r a i n e d sands c o n t a i n t h c impor tan t aquifers i n the area. I n t h e majn v a l l e y t h c s c d e p o s i t s can be d iv ided i n t o a lo\ser and an upper p a r t . The lower par t i s be l i eved t o b e d i v i s i b l e i n t o s i x units, A t o F . Only units D , E and F , two of which ( D and F) arc a q u i f e r s may extend from Enderby on the Shuswap Rive r t o Okanagan Lake. These a q u i f e r s d e s c r i b e d as s a n d and g r a v e l w i t h s i l t v a r y i n p c r m c a b i l i t y from low, about 10 i g p d / f t 2 t o a h igh about 300 i g p d / f t . These v a r i a t i o n s i n p c r m c a b i l i t y occur from l o c a l - i t i e s where t h e a q u i i c r s a rc predominant ly s i l t y - t o t h o s e where t h c a q u i f e r s c o n s i s t of c l ean sand and g r a v c l . from about 80 t o 150 f e c t .

2

Aquifer t l i j cknesscs range

Aqui fcrs i n t h e upper p a r t of t h e s u r f i c i a l d e p o s i t s a r e o€ l esser areal e x t e n t b u t vary cons idc rab ly i n t h i c k n e s s . In t h e area sou th o f Arnistrong aqu i f e r m a t e r i a l s average about G O O f ee t t h i c k towards t h e c e n t r e of the va l l ey (F igure C ) . Near t h c v a l l e y s i d e s f a n d e p o s i t s form sand and gravel. aquj . fers having known t h i c k n e s s c s from 10 to 50 f ee t and a r c p robab ly t.lij.cker. Thc a q u i f e r s i n bo th t h e upper and lower p a r t s of t hc su r f j . c i a .1 dc1 )os j . t~ a r c conf incd , i , e . the wa te r l c v c l I - i scs above the t o p o f t l ic aq i i i fe r . A t some l o c a t i o n s t h e aquifers a r e a r t c s i a n . Coiidi.tj.ons o f rcgionctl ;n-tcsinn floiiv condi t io i i s a r c associated wi th thc fan dc13osj.t.s f lankj ng p a r t s of tlic east. v a l l c y w a l l .

7

A modcratcly impor tan t a q u i f e r t r e n d i n g from sou t lmcs t t o n o r t h e a s t occurs i n a bedrock clianncl about 4!5 iiij l cs n o r t h of Armst-rong. The aqui f c r s i n t h i s v a l l e y and the 0 ' Kccfe Val lcy a re unconf:tncd (o r w a t e r t a b l c ) a q u i f e r s .

\Vcll Yie lds . -

Well y i e l d s , i n t h e dcpth range 700 t o 1 , 2 0 0 f c c t , vary cons idc rab ly i n the m a i n v a l l c y a rea . Yic lds range up t o 10 igpm f o r w e l l s s u i t c d t o doincstic s u p p l j e s t o 500 igpm o r possjLl>; more f o r wells s u i t e d t o i n - d u s t r i a l o r i r r i g a t i o n rcquircnients . igpin o r over a r e a n t i c i p a t e d from wclls 800 t o S75 f c e t dccp. from s i m i l a r l y dccp w e l l s e l se i there i n tlic main v a l l e y a re a n t i c i p a t e d t o b c lo\+, from 30 t o 250 igpm.

In the Enclcrby area y i e l d s o f 500 Yie lds

Wells i n t h e depth 1-ange of 300 t o 600 fce t i n t h e Ariastrong area may produce €Tom 200 t o 850 igpin. In t h e O ' I k e f e v a l l c y y i e l d s o f up t o 500 igpi:i a r e an t - ic ipa tcd from wells completed t o depths of about 550 fec t . The narro\c unconfincd a q u i f e r 4% miles n o r t h o f Armstrong i s ex- pec ted t o have well y i e l d s of about 50 igpm. Est imated well y i e l d s w i l l nccd f u r t h c r v c r i f i c a t i o n from p r o p e r l y c o n s t r u c t e d ilnd t c s t e d product ion wells and obse rva t i on wells.

Groundw a t e r Pot e n t i a 1

The t o t a l q u a n t i t y o f r ecove rab le water a v a i l a b l e b y w a t e r mining has been c a l c u l a t e d as 66,500 a c r e - f c e t , M O S ~ o f which \+auld be ob ta ined from t h c 0 ' Keefe v a l l e y . Ilowever, as. t h e rec:liai-gc from p r e c i p i t a t i o n . i n t h c O'Kecfe v a l l e y i s e q u i v a l e n t t o o n l y about 3 /4 cfs (540 a c f t / y r ) t h c l cng th o f t ime r e q u i r e d t o r e p l c n i s h t h e supply would be about 100 y e a r s . The p o t e n t i a l a v a i l a b l e f o r groundwater withdrawal w i thou t d c p l e t i n g suppl i .cs i s cst i rnated a t from 3 1/3 t o 6 cfs . I t i s b c l i e v c d t h a t present . u t i l i z a t i o n of groundwater i s n o t c l o s e t o t h e lower f i g u r e s . This p o t e n t i a l does n o t i n c l u d e t h a t of t h e Enderby a rea \vhicli f a l l s i n t h c hydro log ic r e g i n c o f the Shusviap R i v e r Yal lcy .

Wa t c I.-l;'C 1 1 c o s t s

0 8

Thc chcmical q u a l i t y o f t h e groundwaters i s vcry good. The t o t a l d i s - solved s o l i d s c o n t c n t o f groundwatcrs i n t h c s t u d y a r e a i!; commonly from about 200 t o 500 ppm. I t i s p r i m a r i l y ca lc ium and magnesium b i - ca rbona te typc wa te r . i on and €or i r r i g a t i o n usc and should r e q u i r e on ly very l i t t l e t r ea t - mcnt f o r i ndus tri a1 purposes .

Thc water i s q u i t e sui t a b l e f o r human consumpt-

Suh - 13 a s i n Gro undw 3 t e r S t ud i cs

As sub-bas ins a re v i r t u a l l y u n s e t t l c d , any s tudy of t h e groundwater rcgimc might f i r s t be directed toit'ards q u a l i t a t i v e r econna i s sance t y p e f i e l d mapping of n a t u r a l phenomena such as s p r i n g s . Most. of t h e prc- c i p i t a t i o n OCCUYS above 4,000 feet and i n con junc t ion w i t h t h i s , most of t h e groundwater d i scharge i s t o b e observed above t h i s e l e v a t i o n .

Sub-basin s t u d i e s g e n e r a l l y prove low basef lo \cs and t h a t t h e groundwater compoiicnt of t o t a l runoff i s small. groundwater d i scha rge from t h e sub -bas ins t h a t i s n o t measured as s t reamflow.

Iliere is l i k e l y ve ry l i t t l e

GLOSSARY OF TERMS

Aquifer . e n t q u a n t i t i e s of wa tc r t o a well t o b e of consequcnce as a s o u r c e o f wa t e r s upp 1 y .

An a q u i f e r i s a water -bear ing f o r ~ c s t i o n t h a t y i e l d s s u f f i c i -

Unconfined a q u i f c r . a b l e rock m a t e r i a l s occu r r ing a t o r n e a r ground s u r f a c e and recharged d i r e c t l y by p r e c i p i t a t i o n . i s c a l l e d t h e wa tc r t a b l e .

An unconfincd a q u i f e r i s one c o n s i s t i n g o f perme-

The upper s u r f a c e o f an unconfined a q u i f e r

Confined a q u i f e r . fer, occurs where groundwat.er is conf ined under p r e s s u r e g r e a t e r t han atmospheric by

A confined a q u i f e r , a l s o known as an a r t e s i a n aqui- -- ovcr ly ing , r e l a t i v e l y inipcrmeable m a t e r i a l .

Ar t e s i an water. water t a b l e , b u t does no t n e c e s s a r i l y r i s e above t h e land s u r f a c e .

Water i n an a q u i f e r i n ' w l i i c h t h e w a t c r rises above t h e

Flowing a r t e s i a n wa te r i s w a t e r which r i s e s above t h e land s u r f a c e .

Water l c v e l contours -- a r e l i n e s , j o i n i n g p o i n t s o f equal e l e v a t i o n above mean sea l e v c l , drawn f o r t h e water t a b l e o r f o r an imagj.nary water l e v e l s u r f a c e of a confined a q u i f c r .

Groundwater d iv ide . a l i n e on a wa te r l e v e l s u r f a c c on each s i d e of which groundwater flows i n a d i r e c t i o n away from t h a t l i n e .

A groundwater d i v i d e i s t h c h i g h e s t e l e v a t i o n of

Hydraii l ic g r a d i e n t . r a t e of change o f e l e v a t i o n p e r u n i t of d i s t a n c e i n t h e wa te r l e v e l s u r f a c c . mile, o r i n o t h e r ways.

The h y d r a u l i c g r a d i e n t i n a given d i r e c t i o n i s t h e

The g r a d i e n t can bc expres sed i n pe rcen tage , i n f e e t p e r

Pe rmeab i l i t y . The f i e l d c o e f f i c i e n t of pe rmeab i l i t y ( h y d r a u l i c con- d u c t i v i t y ) i s de f ined as t h e flow o f wa te r i n ga l lons p e r day through a c r o s s - s e c t i o n of a q u i f e r 1 f o o t t h i c k and 1 mi le wide under a hydrau- l i c g r a d i e n t o f 1 f o o t / l mile a t f i e l d tenipesature .

Trans in iss iv i ty i s t h e product of p e r m e a b i l i t y m u l t i p l i e d by t h e a q u i f e r thic1;ncss and i s exprcssed i n g a l l o n s p e r d; iy/foot .

___---- P a r t s pc1- mi' l l jon. l u t e i n 1 kilogi%m of s o l u t i o n , o r i n cach m i l l i o n pounds of wa tc r t l i e rc i s one pound of d i s so lvcd s o l i d s .

One p a r t p e r m i l l i o n represents 1 mi l l ig ram of SO-

To ta l clissolvcd s o l j Js i s t h c t o t a l concen t r a t ion of d i s s o l v c d mi.ncra1

-..- 1lytlro::r;q~h. A gr;iph showing stage , f low, vcloci . ty o r otl tcr property

(-0 2 c. - --..-

of water w i t h respect t o t ime.

Ilydrogeology can be d c f i n e d as t h c s t u d y o f g r o u n d \ ~ a t e r w.ith p a r t i c u l a r cmp1iasi.s gi';;en t o i t s chciiiistry , movement, arid r e l a t i o n t o the g c o l o g i c e n i i roiiment .

(0 Ir. ..

I

0

P

The author espec ia l ly wishes to acknowledge the ac t ive f i e l d p a r t i c i - pat ion i n this study by Nr. E. C . Halstead, Eydrogeologist, Inland Waters Branch, Department of Environnent, Government of Canada and Mr . P. Hall, Hydrogeologist, GroudiJater Division, Flater Invest igat ions Branch, B r i t i s h Columbia Water Resources Service, whose wri t ten contr i - butions a r e contained within this report . t o the comments of both men and D r . J . C . Foweraker during the planning . s tages of the work. drawn up pr imari ly by D r . J. C . Fowcraker, not only f o r 1970 bu t a lso f o r subsequent years, p r i o r t o t he wr i t e r ' s employment with the Ground- water Division. personnel. the Groundwater Review Board, Mr. D. H. Lennox, Head, Groundwater Sub- divis ion, Inland Waters Branch, Mr. E. C. Halstead, Research Sc ien t i s t , Hydrologic Sciences Division, Inland Waters Eranch, and by D r . J. C . Foweraker, Chief, Groundwater Division, Water Invest igat ions Branch.

The author is also indebted

The overa l l groundwater program of studies was

Field t r i p s have a l so been made with the foregoing Editing of the f i n a l repor t was car r ied out by members of

Most of t he 1970 f i e l d season was spent i n the company of technical s t a f f members, Mr. J. Gulliver and llr. D. Johnson. M r . Gulliver did considerable mrk on contract prspa-at ions f o r seismic, h s t d r i l l i n g 2nd p.,'~rrp test program being i n c o n s t m t cornimnication with the Chief of the Dids io i i during this t ine . I n k . D. J o h ~ ~ s o n proved a worthy technical a s s i s t a n t on sub-bzsin fieldwork. Mr . J. Jaundrew joined the former men on t e s t d r i l l i n g Coatracts 42 and 43 conducted under TaskhO. plr. A . Allport was f i e l d assis taf i t an Task 41 i n 1971.

Thanks must be expressed to Yir. \I. E a i l e j r , Provincial Sani tary Engineer, D r . 1.1. R. Smart, Director, North Okanagan Health U n i t , Vernon and to D r . D. A . Clarke, Director, South Okanagan Health Unit, Keloma, f o r help i n obtaining copies of chemizel analyses of groundwa+&rs. 1-k. A . Lynch and Ilrs. I. Kalnins, Provincial Water Resources Laboratory and k. S . Reedcr, Federal G o x n x e n t Laboratory, Calgary ran chemical a-d.yse3 on grcjcfidxater smples sutmitted as p z r t of the program of s tud ies . Aclmowledeement i s made t o M r . D. Currie regarding notes on the planning stages of sub-basin groundwater s tudies and to Mr. O r o s t Tokarsky f o r several helpful suggestions i n hy+rogeol.ogical napping. Bot5 men a r e hydrogeologists with the Groundvate? Division, Research Council of Alberta .

v i i

The au tho r wishes to acknowledge t h e work of t h e men of both d r i l l i n g companies involved i n the test d r i l l i n g programs, Wardean D r i l l i n g Company Limi ted and Big Ind ian D r i l l i n g Company L i m i t e d . I n v a l u a b l e h e l p was provided i n commencing the mud progr.ams, under Con t rac t 42, by Mr. D. Larsen and under Con t rac t 43, by I k . C . Laing, Imth of Baroid Nud Company. P l r . J. Ploore, Osoyoos T i l e h'orks and l i n t e r Wells. very coope ra t ive i n o f f e r i n g l a n d s i t e s f o r t e s t d r i l l i n g and permi t - t i n g seisnr ic ope ra t ions on t h e i r p rope r ty . by Nr. P. Dixon and 1I.r. W. Mclnnes.

t:-o

The test pumping c o n t r a c t was c a r r i e d o u t by Local res idents were

I l raught ing has been done

0

. . .

SECTION I

A HYDROGEO1,OGICAL STUDY OF THE NORTI-l END

OF THE OKANAGAN R I V E R BASIN

E. Gordon Le Breton

Water Inves t i .gations Branch

CONTENTS

ILI,USTRATIONS AWD TABLES

SUMMARY

ACKNOWLEDGF-TS

1.

2.

3.

4.

5 .

6.

INTRODUCTION

1.1 Methods of investigation 1 .2 Previous Investigations

GE0GRAPH-X 2.1 2.2 Topography and Drainage 2.3 Climate

Location and Extent of the Area

GGOLX)GY

3.1 Bedrock Geology 3.2 Structure 3.3 Surf i c i a l Deposits

SEIXC EXPIBUTION (TASK 38) 4.1 Objective 4.2 The Seismic Program 4.3 An Analysis of the Seismic Progr-m

ROT.4RY TEST-HOLE D3ILISNG PROGWIS (TASK 40)

5.1 Objective 5.2 Achievements

HYDROGEOLOGY

6.1 6.2 6.3

6.5 6.6 6.7 6.8

6 -4

6.3

General Statement Basic Water-well Data Aquifers i n the S u r f i c i a l Deposits Groundwater Movement, Recharge and

Transmissivity Values Water-well Yields (Task b1) Groundwater Flow Calculations Theoretical Calculation of Recharge Hydrogeochemistry

Discharge Areas

Page

1

ii

ii.i - v i

v i i - v i i i

1

1 2

5 5 5

9 9 9

10

10 10 10

11 13 15 1 5 18 20

7.

8.

9 .

10.

11.

EVALUATION OF RESULTS

POTENTIAL GROWDWATER DEVELOPMENT

8.1 8.2 8.3 8.4 Parkinson Bedrock Channel Aquifer 8.5 Groundwater Mining

Lower Par t of the S u r f i c i a l Deposits Upper Pa r t of the Sur f i c i a l Deposits 0 'Keef e Valley Aquifer

ECONOMICS OF GROUNDWATER DEVEUIR4XNT

9.1 9.2

Costs of groundwater f o r High-yield Wells Costs of groundwater f o r Low-yield Wells

CONCLUSIONS

REFERENCES CITED

APPBdDIX A - Okanagan Valley Seismic Survey, Revised Final Report, by R. M. Lundberg, P. Eng.

APPZNDIX B - Composite t e s t hole logs, Contracts L2 and 43.

ILLUSTRATIONS

Figure 1

Figure 2 Diagramatic cross-section, Okanagan

Hydrogeological map, North Okanagan River Bas i n

22

23

23 24 25 25 26

28 28 30

31

33

34

41

A f tor page

( I n pocket)

10 -

Drainage Basin showing eas t face-of Section with inferred gross Groundwater flow di rec t ion

Figure 3 Time-drawdown graph: Pump Test No. 2, C42 TH1 14

Figure 4 Time-drawdown graph: Pump Test No, 2, C42 TH2 14 Figure 5 Time-drawdown graph: Pump Test No. 1 , C42 TI13 14

Figure 6 Time-drawdown graph: Pump Test No. 2, C43 TH2 15

Figure 7 Areas indicated f o r groundwater exploration 23 Index >kip 87

TARLES --..

Table 1 Table of Pumping Test Infomation 4

,

i-

(Reference -- Hydrogeological map North End Okanagan River Basin -- Pocket of Report. )

The groundwater program discussed herein, i s p a r t of a comprehensive study of the water resources of the Okanagan Basin being conducted under the Canada-British Columbia Okanagan Basin Agreement signed i n October, 1 969.

The objectives of the groundwater investigations were t o try t o determine the groundwater flow i n t o and from Oknnagan Lake, t he groundwater po ten t i a l of the va l l ey - f i l l deposits, and t o determine the groundwater component of s i x selected sub-basins to more f u l l y understand the hydrologic budget of the Okanagan River Basin. have been conducted under Tasks 38, 39, 40 and 41.

The purpose of t h e seismic work (Task 3 9 ) , was to obtain information on the depth to bedrock across several sections i n the Okanagan and O'Keefe Valleys, t o try t o determine the nature of the v a l l e y - f i l l depos i t s , to help to reduce the number of test, holes required to locate the th ickes t sect ion of overburden, and to help s e l e c t the type of d r i l l i n g equipcent required t o accomplish t e s t d r i l l i n g .

To this end s tudies

"he seismic survey proved t o be a very valuable technique f o r enabling the Groundwater Division to pick the deepest pa r t s of the va l ley f o r test-hole d r i l l i n g . 6 seismic p ro f i l e s and were poor only close t o the valley walls.

Results proved to be qui te good across much of the

Task 40 consisted of deep and intermediate depth ro ta ry- tes t d r i l l i n g programs. t o drill through tke overburden t o the bcdrock, and to provide information on the type, thickness and continuity of the va l l ey - f i l l depos- i t s , to study geologic s t ruc ture of t h e main valley, and a l s o to check on the valae of prel?uninaiq so isn ic cxpl-oration. The results could be used as a n ind ica tor for assessing groundwater resources and f o r making theore t ica l estimates of gpouridwater flow towards Okanagan Lake. a d d i t i o n to the 2bove planiicd objectives, t h e t e s t holes were l e f t cased t o be used a s observat im wells.

The puivose of the t e s t hole d r i l l i n g was i n i t i a l l y designed

I n

The objective of Task 4l wa.9 t o obtair, supplementary data concerning groundiiater qua l i ty and r e l i a b l e estima-Les of the r a t e s ,at which water can be produced frcm a s ingle w e l l OT from a well- f i e l d extending over a r e l a t ive ly l i n i t e d mea. The data c o l l e c k d could be used to s e l e c t

k. - The O'Keefe Valley aquifer, i n the important t r ibu tary val ley i n the area, extends throughout the e n t i r e length of t h i s ( the O'Keefe) valley. 575 feet , of which the saturated thickness is close t o 3!;O f ee t . . A t the south end of the val ley the aquifer consists primari:ty of clean sand and gravel, bu t a t the north end thedeposits a r e known only from surf ace f i e l d mapping.

The m a x i m u m known thickness of the deposits i n this val ley i s

A moderately important aquifer trending from southwest to northeast occurs i n a bedrock channel about 4% miles north of Armstrong. The aquifers i n t h i s va l ley and the O'Keefe Valley are unconfined (or water tab le) aquifers . Well yields , i n the depth range 700 t o 1200 feet , vary considerably i n the main vs l l ey area. Yields range up t o 10 i g p m f o r wells su i ted t o domestic supplies t o 500 igpm o r possibly more f o r wells su i ted to indus t r i a l o r i r r i g a t i o n requirements. I n the Enderby area yields of 500 i g p m o r over are ant ic ipated from wells 800 to 875 f e e t deep. Yields from similarly deep wells elsewhere i n the main val ley are ant ic ipated t o be low, from 30 t o 250 i g p m .

Wells i n the depth range of 300 to 600 f e e t i n the Armstrong area may produce from 200 t o 850 igpm. I n the O'Keefe val ley yields of up to 500 igpm are ant ic ipated from wells completed t o depths of about 550 feet . The narrow unconfined aquifer 4% miles north of Armstrong is expected to have'well y ie lds of about 50 igpm. will need fur ther ver i f ica t ion from properly constructed and tes ted production wells and observation wells.

Estimated well y ie lds

From underflow calculations a t o t a l rate for groundwater movement towards Okanagan Lake of about 3 1/3 cfs (2370 acf t /yr) has been determined. 6 c f s (4350 acf t /yr) from 1 inch o f prec ip i ta t ion reaching the water table over a recharge area estimated as 80 square miles.

This figure seems reasonable compared to a recharge rate of

The t o t a l quant i ty of recoverable water available by water mining has been calculated as 66,500 acre feet , most of which would be obtained from the O'Keefe valley. However, as the recharge from prec ip i ta t ion i n the O'Keefe val ley i s equivalent t o only about 3/4 c f s (540 acf t /yr) the length of time required t o replenish t h e supply would be about 100 years.

"he poten t ia l avai lable f o r groundwater withdrawal without depleting supplies i s estimated a t froin 3 1/3 t o 6 cfs . present u t i l i z a t i o n of groundwater i s not c lose to the lower figures. This po ten t i a l does not include t h a t of the Endarby area which f a l l s i n the hydrologic regime of the Shuswap River Valley.

It i s believed that

The chemical qua l i ty of the groundwaters i s very good. solved so l id s content of groundwaters i n the study area is commonly from about 200 to 500 ppm. It i s pr immily calcium and magnesium bi - carbonate type water. ion and f o r i r r i g a t i o n use and should require only very l i t t l e treatment f o r i ndus t r i a l purposes.

The economics of groundwater development indicate tha t f o r one l o c a l i t y l imited preliminary groundwater investigations including some seismic, tes t d r i l l i n g and pump t e s t ing may cost about $45,OOO. High y ie ld production wells producing about 800 igpm including pump and pump house a r e estimated to cost from $25,000 t o $50,000 the ac tua l costs varying with such f ac to r s as d i f f i c u l t y of d r i l l i n g conditions and well diameter.

The t o t a l d i s -

The water i s qui te su i tab le f o r human consumpt-

Task 38 comprised a study of 6 sub-basins. The objective of the reconnaissance s tudies was to determine whether or no t the groundwater component of sub-basins was i n s u f f i c i e n t volume t o warrant expenditure of more time and funds t o provide as complete as possible an assessment of its contribution to the hydrologic regime.

Sub-basin s tudies generally prove low baseflows and that the groundwater component of total runoff is small. groundwater discharge from the sub-basins that is not measured as streamflow.

There i s l i k e l y very l i t t l e

It may be s t a t e d tha t the groundwater program car r ied out, under the j o i n t Canada-British Columbia Okanngan Bas in Study agrement considerably increases knowledge and understanding of the hydrogeology of the north end of the Okanagan River Basin and of' some selected sub-basins.

vi

ACKNOWLEDGEMENTS

t...

The author especial ly wishes to acknowledge ac t ive f i e 1 par t i c i - pat ion i n this study by Mr. E. C. Halstead, Ivdrogeologist, Inland Wate;s Branch, Department of Environment, Government of Canada and Mr . P. Hall, €&drogeologist, Groundwater Division, Mater Invest igat ions Branch, Brit ish Columbia Water Resources Service, whose wri t ten contributions are contained within this report. t o the comments of both men and D r . J. C . Foweraker during the planning s tages of the work. drawn up pr imari ly by D r . J. C . Foweraker, not only f o r 1970 bu t a l so f o r subsequent years, p r io r t o the wr i t e r ' s employment with the Ground- water Division. personnel. the Groundwater Review Board, M r . D. H. Lennox, Head, Groundwater Sub- division, Inland Waters Branch, Mr. E. C. Halstead, Research Sc ien t i s t , Hydrologic Sciences Division, Inland Waters Branch, and by D r . J. C . Foweraker, Chief, Groundwater Division, Water Investigations Branch .

The author is also indebted

The overa l l groundwater program of s tud ies was

Field t r i p s have a l so been made with the foregoing Editing of the f i n a l repor t was carr ied out by members of

Most of the 1970 f i e l d season was spent i n the company of technical staff members, Mr. J. GLLliver and Ilr . D. Johnson. M r . Gulliver did considerable m r k on contract preparations f o r seismic, test d r i l l i n g and p q test programs being i n constant communication with the Chief of the Division during this time. 14r . D. Johnson proved a worthy technical a s s i s t a n t on sub-basin fieldwork. Mr. J. Jaundrew joined the forner men on tes t d r i l l i n g Contracts 42 and 43 conducted under TaskhO. Mr. A. Allport was f i e l d a s s i s t a n t an Task 41 i n 1971.

Thanks must be expressed to Mr. W. Bailey, Proifincia1 Sanitary Engineer, D r . M. R. Smart, Director, North Okanagan Health U n i t , Vernon and to D r . D. A . Clarke, DirectoT, South Okanagan Health Unit , Keloma, f o r help i n obtaining copies of chemical analyses of groundwa+&rs. Mr. A . Lynch and Nrs. I. Kalnins, Provincial Water Resources Laboratory and Nr. S . Reeder, Federal Government Laboratory, Calgary ran chemical analysea on groundwater samples submitted as p a r t of the program of s tud ies . Acknowledgement is made to Mr. D. Currie regarding notes on the planning stages of sub-basin groundwater studies and t o M r . Orest Tokarsky f o r several helpful suggestions i n hydrogeological nappirig. Both men are hydrogeologists wit,h the Groundwater Division, Research Council of Alberta.

v i i

The author wishes to acknowiedge the work of the'men of both d r i l l i n g companies involved i n the test d r i l l i n g programs, Wardean Dr i l l ing Company Limited and Big Indian Dr i l l ing Company Limited. Invaluable help was provided i n commencing the mud programs, under Contract l.42, by M r . D. Larsen and under Contract 43, by Mr. C . Laing, both of Baroid b d Company. Mr. J. Moore, Osoyoos T i l e Works and Water Wells. very cooperative i n offer ing land sites f o r t e s t d r i l l i n g and permit- t i ng seismic operations on t h e i r property. by Mr. P. Dixon and Mr. W. McInnes.

The test pumping contract was carr ied out by Local res idents were

Draughting has been done

viii

t.

A HM)ROGEoILx;ICAL STUDY OF THE NORTII END OF TKE OKANAGAN RIVER BASIN

1 . IN!I'RODUCTION

The purpose of this study was twofold, one t o t r y to determine the groundwater flow i n t o and from Okanagan Lake and the groundwater po- t e n t i a l of the main va l l ey - f i l l deposits, par t icu lar ly i n the area from the north end of Okanagan Lake to the town of Enderby on the Shuswap River, and two, to determine the groundwater component of six selected sub-basins to more fully understand the hydrologic budget of the Okanagan River Basin.

1.1 Methods of Investigation

For information on the geology of the Okanagan River Basin, reference was made to geological maps and reports of the Geological Survey of Canada and the Department of Mines and Petroleum Resources, Province of Br i t i sh Columbia and to l i t ho log ic logs and e l e c t r i c hogs. A i r photos were used t o supplement f i e l d studies . Forest cover and topographic maps of the Department of Lands, Forests and Water Resources, Province of Br i t i sh Columbia and reports of the Departanent of Mines and Petroleum Resources, were used f o r information on vegetation and landforms of the region.

Existing water-well records on f i l e i n the Groundwater Division sup- p l i ed by water-well dri l lers o r obtained from water-well inventories, were p lo t ted and interpreted; these records form an important p a r t of this report . Also used were data obtained from other Government agen- c ies and l o c a l unpublished areal groundwater investigations. elevations of most wells, test holes and f i e l d features were es t imated from 1 inch t o 12,000 inch and 1 inch to 50,000 inch topographic maps.

The

I n addition to studying exis t ing information, preliminary hydrogeo- log ica l investigations of a qua l i t a t ive nature were unde~taken to understand more about the groundwater regime of selected sub-basins (Task 38). portant preliminary work on which t o base the fa r more expensive groundwater-tes t d r i l l i n g programs (Task bo). A w e l l development and t e s t punping program (Task 41) was conducted f o r t he purpose of e s t i - mating w e l l y i e l d s i n the tes t holes completed under Task 40. 38 to LO were completed i n the 1970 f i e l d season and Task 41 i n the 1971 field season.

Seiomic investigations (Task 3 9 ) were conducted as i m -

Tasks

I 1.2 Predous Investigations '.

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Local areal investigations were Livingston, P. Eng., Consulting Groundwater Division, by Dr. J. of the Groundwater Division and

previously carr ied out by Mr. E. Groundwater Geologist, formerly Chief, C . Foweraker, P . Ehg., present Chief by other staff members. Publications

directly concerned with groundwater s tudies i n the Okanagan River Basin, include "Groundwater Investigation - Mount Kobau, B r i t i s h Columbia", E. C. Halstead, Inland Waters Brmch, Department of the Environment, Government of Canada (1 969) .

2

a 2. GEOGRAPHY

3

2.1 Location and &tent of the Area

The Okanagan River Basin l ies between pa ra l l e l s of l a t i t ude 49°001 and !W401 north and between meridians of longitude 1 1S045 west. of the drainage basin i n Canada is. 3018 square miles. However, in t h i s hydrogeological study, emphasis i s placed on the f la t te r - ly ing areas i n the north end of the main val ley and the O'Keefe t r ibu tary valley which comprise the se t t l ed area:!, and on some selected sub-basins. The t o t a l area of the main val ley (to about 1,500 f e e t above sea leve l ) i s about 215 square miles of which 131 square miles is occupied by Okanagan Lake, and only about 70 square miles i s land area. The total area of the sub-basins is about 350 square miles.

and 1 20'1 8 The t o t a l area

0 (

0 i '..

"he Okanagan River Basin falls par t ly within the Thompson Plateau which has a gently ro l l ing upland of low r e l i e f , within the Shuswap Highland consisting of gentle o r moderate sloping plateau areas, and the Okanagan Highland which includes rounded mountains and ridges and gentle open slopes. Within the Okanagan River Easin the:je areas a re dissected by numerous shor t creeks. (Holland, 1964).

2.2 Topography and Drainage

Okanagan Lake is the pr incipal body of water occupying the main Val- ley. lakes of Skaha and Vaseux before entering 03oyoos Lake a t the south end of the valley. water mvement a re the O'Keefc Valley trending north to south entering the iwin valley near the north end of Okanagan Lake, Mission Creek Valley entering Okanagan Lake approximately near the centre of the e a s t side of the lake, and Coldstream Valley running from the east and entering the main lake south of the town of Vernon.

Okanagan River flows from the south end and through the smaller

"he important t r ibu tary valleys i n terms of ground-

The elevation range of the basin l i e s mainly between 1,030 and 6,000 f e e t above sea level. The distance from the dra-image ba,sin divides to the main val ley i s a3 rmch as 30 miles, but is commonly less than 15' miles. with an i n i t i a l l y rapid r i s e to 4,000 or 5,000 f e e t from the main val ley floor a t 1,000 to 1,600 f e e t per mile fo r 3 t o 4 irniles. 4,000 fee t , the average slope is much less , up to 300 f e e t per mile.

Gradients range from nearly ve r t i ca l t o nearqy horizontal,

Above

2.3 Climate

Tho climate of the &ea, accordhg to Kappen's c lass i f ica t ion , is

4 Middle Latitude Steppe (BSk) i n which B = Dry climates, S = Semiarid, and k = Cold; mean annual temperature l e s s than 64.4OF but mean t e m - perature of warmest month over 64.1.i°F. (Canada, Department of Mines and Technical Surveys , 1 957. ) 47.90F a t Oliver i n the south end of the valley, and lr4.6OF a t Arm- st rong i n the north end. The respective averages f o r prec ip i ta t ion a re 10.79 and 17.18 inches per year.

'o The average temperature ranges between

i

3.1 Bedrock Geology

A description of the bedrock geology, f o r the purposes of this report , is l imited to the north end of the Okanagan Valley f r o m Enderby on the Shuswap River to Okanagan Lake. The bedrock geology can be divided i n t o 3 main subdivisions. One, rocks of the Monashee Gmup occur on the east s ide of the valley. These rocks comprise mainly gneiss, but sch i s t , qua r t i z i t e , calcareous gneiss and marble are common. The rocks exhib i t metamorphism of uniformly high grade and are of sedimentary or ig in (Jones, 1959). The other two subdivisions occur on the west s ide of t h e valley separated from the former by the Vernon-Sicamous f a u l t system. Rocks of the Mount Ida Group are of both sedimentary and volcanic or ig in and have been subjected t o low grade metamorphism. These rocks comprise mainly ch lor i te and s e r i c i t e schis t8 and garneti- ferous quartz-mica sch is t s , and quartzi te . To the south:, and i n faul t contact wjth the Mount Ida Group, i s the Cache Creek Group. The Cache Creek Group comprises mainly a r g i l l i t e , andesite lava and limestone. Minor occurrences of Tertiary lavas are also t o be seen ( F i g . 1 - Pocket of Report).

3.2 Structure

"'Faults i l l u s t r a t e d on the map represent some of t h e latest deforma- t i o n i n the Vernon map-area.. . . The amount of movement 011 these faults i s not known...and the i r regular f a u l t boundaries between major rock groups s igni fy that movements are mainly v e r t i c a l ra ther than horizontal" (Jones, 1959). from Armstrong and they appear t o exer t a strong tectonic influence on the bedrock gradient of the thalweg f o r the main valley. sults i n e i t h e r a steep gradient between t e s t holes C42 TH2 and C42 TH3, or of a generally uniform gradient interrupted by a de f in i t e f a u l t . o ld stream bed t o allow f o r subsequent erosion within t h e bed following fau l t ing . and probably crosses the val ley j u s t north of Cb2 TH2. d i rect ion is obscured by the s u r f i c i a l deposits within t h e main val ley and by the above mentioned Tertiary lavas (Fig. 1 ) .

An important s y s t e m of f a u l t s trends northwest

T h i s re-

The former in te rpre ta t ion i s preferred f o r the course of the

A f a u l t is shown trending northwest near :Kendry Creek However, i t s

3 .3 Surf i c i a l Deposits

The references used i n t h i s repor t fo r describing the s u r f i c i a l geologJr (Fig. 1 ) of the Okanagan region are maps by Fulton, R. (1969, Maps 1 2 4 b and 124sA) and a repor t with maps by Nasmith, H. (1962). foregoing maps show areas of mainly bedrock about 2,500 feet o r

The

6 probably th in morainal deposits over bedrock above-about 1,500 feet. The morainal deposits are chief ly till, which is a deposit of unsorted sand, silt , clay and boulders. Below elevations of 1,SOC) fee t , and predominantly on the eas t s i d e of the valley, occur numerous fan o r fan-delta deposits of gravel and sand. Coarse sand and gravel deposits on the west side of the main Okanagan Valley a re t o be found associated almost en t i r e ly with the O'Keefe t r ibu tary valley and tho "lower pa r t " of Deep Creek valley before it enters the main valley. of the main val ley to be seen a t ground surface are commonly s i l t and some clay.

The deposits

A t this point i n the description of the s u r f i c i a l deposi1;s a t ten t ion i s drawn to the north-south (Fig. 1 ) and east-west (Fig. 1) cross sections f o r the north end of the main valley. of the test d r i l l i n g conducted under Task 40, i s the regional picture which can be constructed of the s u r f i c i a l deposits of the main valley. These can be divided into two par t s -- lower and upper par t s . The lower p a r t of the sediments shows an al ternat ing sequence of till, clay and silt, sand and gravel zones divided in to units A to F. sequence ranges from about 300 f e e t thick i n the north at, C43 THS t o about 750 f e e t thick in the south a t C42 TH1. The till zones range f r o m about 40 to 100 f e e t t h i ck ; s i l t , sand and gravel zones are about 80 to 220 f e e t thick, and a c l ay - s i l t zone i s about 100 f e e t thick. Facies changes within these layers may be duo to non-deposition in some pa r t s of the valley, o r t o removal and subsequent replacement by l a t e r glaciations. The uppermost of these s i l t , sand and graval zones is the one i n which most of the deep t e s t holes were completed a s observation wells. Tho units A to F have been denoted i n ascending order.

Overlying the succession of tills and sands, and comprising the upper p a r t of the main valley deposits, is 500 t o 1,000 f e o t o f sediments that are m i n l y s i l t . the secponce, and of par t icu lar importance t o this study are the thick svlds occurring i n the Maid Creek area south of Armstrong. i n the upper p a r t of the s u r f i c i a l deposits are cornonly f i n e tomedium- grained, angular sanh .

An important r e s u l t

T h i s

There are some sand beds i n the upper p a r t of

The sands

Considerable loca l var ia t ions are ant ic ipated within the upper p a r t of the s u r f i c i a l deposits. Local d e w s i t s of gravel and sand on the eas t s ide of the val ley are a t t r ibu ted t o meltweters from tri'butary valleys, and sands on the west s ide of the Naid Creek cross section may have been derived i n association with meltwaters discharging to the south from Ijeep Croek (Fig. 1 ) . It may also be observed that there i s down- val ley thickening of both the upper and lower par t s of the va l l ey - f i l l deposits.

4.1

7

4. SEISMIC EXPLORATION (TASK 3 9 )

Objective

The purpose of the seismic work was to obtain information on the depth to bedrock across several sections i n the Okanagan and O'Keefe Valleys, to try to determine the nature of the va l l ey - f i l l deposita, t o help to reduce the number of t e s t holes required t o locate the th ickes t sect ion of overburden, and t o help s e l e c t the type of d r i l l i ng equipment required t o accomplish test d r i l l i ng .

4.2 The Seismic Program

During the month of June 1970, reconnaissance f i e l d t r i p s were made t0 evaluate the f e a s i b i l i t y of running seismic l i nes a s chosen during the o f f i ce planning stages of the groundwater program. also e s sen t i a l t o gain permission t o run seismic l i n e s across private- ly-owned land. Adjustments subsequently made proved to be d n o r . The program was directed by a consulting geophysicist, and an independent seismic conrpany ran the p ro f i l e s during the month of July. Four pro- f i l e s were run i n the north and two i n the south p a r t of the Okanagan River Basin.

These t r i p s were

The i n i t i a l results showed the longitudinal bedrock val ley p ro f i l e , along the deepestp-ts of the cross sections, increased in depth below ground surface from about 800 f e e t a t Enderw t o about 1,600 f e e t a t Armstrong. end of the val ley a t Okanagan Fa l l s . Surface elevations of the bedrock-valley f loo r r e l a t ive t o sea l eve l were about +3OO fee t a t Enderby, about -600 f e e t a t Armstrong and about +SO0 f e e t near Okan- agan Fal ls . These elevation readings show the bedrock val ley f loor t o be dipping rapidly towards Okanagan Lake a t the north end of the lake, and t o be r i s ing a t the south end of the lake. The table (Appendix A) comparoa predicted and actual depths to bedrock, and f i g - ures 1 and 2 of A p p ~ d j l t A show the i n i t i a l seismic in te rpre ta t ion made prior to b s t d r i l l i n g and the revised interpretat ion following t e s t d r i l l i ng . marily s i l t and sand with some gravel. south end of the val ley (C42 THk, Fig. 4, Appendix A ) penetrated almost a l l sand, g ram1 and boulders.

The depth t o bedrock decreased to 800 f e e t in the south

The va l l ey - f i l l deposits were considered to be p r i - However, test d r i l l i n g a t the

4.3 An analysis of the Seismic Program

The i n i t i a l impression gained by Groundwater Division Staff during a preliminary f i e l d t r i p with Mr. R. Lundberg was that a f a s t , e f f i c i en t and effect ive seismic program was feas ib le i n the Okanagan Valley.

Results bore ou t p r io r opinions. Judgements of the seismic program, this analysis concerns interpre- ta t ions made p r io r to test d r i l l i ng .

Obviously, to form correzt value

Predicted depths t o bedrock made by the seismic consultant were s ta ted to be within + IO$. valley, the pzrcentage errors ranged up to 13% f o r three holes and 17% and 25% f o r two more. walls show considerable e r rors of 110% and 503%. an anomalous layer i n the middle of the valley had an e r ro r of only 2%.

O f f i v e holes d r i l l e d towards the middle of the

However, t e s t holes d r i l l e d close la val ley Predicted depth f o r

Signif icant observations t o be made were t h a t the val ley was f i l l e d mainly w i t h silt and sand. case of the thin silt layer f o r p a r t of seismic l i n e 1 , axe hard to determine due to lack of veloci ty contrasts between the silt and sand. Even during test d r i l l i n g it i s sometimes d i f f i c u l t t o pick l i tho logic changes especially as sands o r silts are often thinly interbedded and much of the sand is of very f i n e grain s ize . in te res t ing conclusion regarding seismic l i n e 4 i n t h a t he expected the water l eve l to be about 200 f e e t below ground surface. evidence from examination of d r i l l i n g samples, suggested an oxidized zone 200 feet thick, and the depth to the water l e v e l rec'orded i n test hole C43 T€& was 193 f e e t below ground surface.

Bed thicknesses, except as i n the spec ia l

M r . Lundberg drew an

Available

The seismic survey proved t o be a very valuable technique f o r enabling the Groundwater Division to pick the deepest pa r t s of the valley for tzst-dril l ing. The seismic resu l t swere the key f ac to r i n select ing the capacity of d r i l l l n g equipment necessary t o penetrate the f u l l thickness of the overburden and d r i l l on in to the bedrock. Similar surveys would appear t o be well worth while i n fu ture deep-valley groundwater exploration programs i n the Province of Br i t i sh Columbia. A copy of Mr. Luridberg's revised f i n a l report is given i n . Appendix A . Copies of the e a r l i e r f i n a l report are available a t the of f ice of the Groundwater Division, Water Investigations Branch, Department of Lands, Forests and Water Resources, Victoria, Br i t i sh Columbia and a t the o f f i ce of the Directar, Canada-British Columbia Okanagan Basin Study Agreement, Penticton, n r i t i s h Columbia. since been presented a t the Llst Internat ional Meeting of' the Society of Exploration Geophysicists, November, 1971 and was published under the t i t l e "Seismic Techniques Applied t o Groundwater Research i n the Okanagan Valley, Br i t i sh Columbia".

Mr. R. Lundberg's work has

8

5.1 Objective

ROTARY TEST HOLE D R I L L I N G P R D G W (TASK 401

Beginning i n late September 1970 and continuing on i n t o ear ly November, two rotary test hole programs were conducted under Contracts 42 and k3. d r i l l through the overburden to the bedrock, and t o provide informatLon on the type, thickness and continuity of the va l l ey - f i l l deposits, t o study geologic s t ructure of the main valley, and a l so t o check on the value of preliminary seismic exploration work. I n addition to this planned objective, the test holes were l e f t cased t o be used a s observation wells. Later, these wells, a f t e r cleaning and development, were used f o r shor t pumping t e s t s to make estimates of well yields and obtain transmissivity values f o r some of the aquifers.

The purpose of the t e s t hole d r i l l i n g was i n i t i a l l y designed t o

5.2 Achievements

Nine holes were d r i l l e d under the above contracts, four dLth a 3,500 f o o t capacity Fail ing r i g t o depths ranging from 850 to 1:,900 f e e t f o r a total cost of $102,000, and f ive wlth a 2,000-foot 'Con-Cor' r i g to depths ranging from 120 f e e t t o j u s t over 900 f ee t , f o r a t o t a l cost of $35,000.

Observation wells were completed i n these test holes mostly with 10 f e e t of four-inch diametsr pipe-size screens, washdown bottom and four- inch casing. construction of some deep 4- t o 7-inch diameter water wel:Ls and success fu l d r i l l i n g of test holes to bedrock using the rotary method under sometimes very d i f f i c u l t d r i l l i n g conditions, marked a major s tep for- ward i n deep-valley groundwater exploration programs i n the Province.

The deepest well screen i s s e t a t 1,21 s' f e e t deep. The

The rotary technique proved t o be quite successful due t o the adoption of a mud program newly-tried i n the Okanagan Valley. This mud kept holes open f o r up to 25 hours, and withstood ar tes ian pressure con- d i t ions until development was begun. of d r i l l i n g and running casing, four geophysical borehole logs were run i n e ight of the nine holes. Kith this report , one s e t being derived mainly from Mr. E. Livingston's work on the deep test holes (Appendix B) . Very thick permeable depos i t s , up to about 800 feet of sand, gravel and boulders, were encountered i n the Okanagan Falls test hole. An interpretat ion of the hydrogeological information obtained from the test d r i l l l n g programs is presented w i t h i n this report and has been used i n the compilation of maps and cross sections.

I n the in t e rva l between the end

Composite d r i l l i n g logs are submitted

9

10

6. *~DROGFX)LOGY

6.1 G ener a1 Statement

Pr ior t o a more de ta i led discussion of the north end of the valley, reference w i l l be made t o f igure 2 contributed to the study by Mr. E. C. Halstead. This shows a diagramatic cross sect ion presenting a conceptual r ep resen ta t im of groundwater flow i n r e l a t ion t o surface drainage f o r the Okanagan River Basin. The stream discharge measurements a t the south end of the valley, f o r the year 1967, are designed to i l l u s t r a t e that some of the water contributed by t r ibu ta ry streams is added t o groundwater o r i s l o s t i n consumptive use (that is by evapotranspiration and diversion) . 16,500 acre feet from Vaseaux Creek is not recorded by the difference i n flow between the two gauging s ta t ions a t Okanagan Fa l l s and a t Oliver. Whatever quant i ty is not l o s t t o consumptive use must be passed through the basin a s groundwater flow (personal communication E. C. Halstead, 1972).

The increment t o groundwater of

6.2 Basic Water-Well Data

Basic information, mainly water-well data submitted by water-well dri l lers and that ' col lected from well inventories, was p lo t ted on topographic maps of a su i tab le scale . maps avai lable are a t a sca le of 1 inch t o 1,000 feet . analysis and synthesis of this data and of data f r o m test, hole d r i l l i n g and pump t e s t ing supervised by the Groundwater Division have been used i n the compilation of figure 1 and i n writ ing t h i s section on hydrogeology. Many of the control points are shallow wells commonly less than 50 fee t deep recording only well depth and the depth to the nonpumping water level .

The most su i tab le topographic R.esults of

6.3 Aquifers i n the S u r f i c i a l Deposits

Based on avai lable data, an attempt has been made to show the areal extent and thickness of some of the aquifers i n the surfj-cial deposits (Fig. 1 ) . f i c i a l deposits t h e i r possible extent and thickness i s shown by the cross sections N-S and W-E. Units D and F m y occur throughout the e n t i r e north end of the Okanagan Valley, the former ranging from about 85 t o 140 f e e t thick and the l a t t e r from about 125 to 150 f ee t thick. Unit F i s considered to be composed mainly of sand and gravel with some s i l t , the s i l t content sometimes being loca l ly predominant as i n C42 TH3. clay, s i l t and sand i n t he south. composed of sand and si l t .

For aquifer Units B, D and F i n the lower part of the sur-

U n i t D shows a change from sand and gravel i n the north to U n i t B, up t o 150 fee t thick, i s

As Unit B i s the deepest aquifer it i s of

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0

smaller areal extent being absent to the north where the bedrock gra- d ien t steepens and i s fur ther l imited by the narrower width with increasing depth between the V-shaped bedrock valley walls. The only major aquifer i n the upper p a r t of the s u r f i c i a l deposits occurs I n the Armstrong area and loca l ly has a known thickness of about 800 fee t . Water l eve l measurements i n wells completed i n both the lower and upper pa r t s of the s u r f i c i a l deposits show the aquifers a r e confined, the heads r i s i n g above the top of the aquifer. In some cases the aquifers a re ar tes ian.

Locally important aquifers of more l imited a rea l extent a r e the numerous fan deposits of sand and gravel flanking the eas t val ley wall. These occur f o r a limited distance toward the centre of the val ley beneath or interf ingering with the Upper Lake Beds. val ley wall these aquifers a re unconfined but beneath the Upper Lake Beds they a r e confined aquifers.

The most important unconfined (water-table) aquifer i n the study area occurs i n the O'Keefe Valley. The map of the s u r f i c i a l geology shoxs sand and gravel deposits occur throughout the en t i r e length of the va l ley (Fig. 1) . TK4) a t the south end of this valley and t o have a saturated thickness of 350 feet. valley. can be mapped as *a contimous water-level surface. considered the water i n the va l l ey - f i l l deposits forms one continuous aquifer and for the purposes of this report i s named the O'Keefe Valley aquifer . I

Another unconfined aquifer occurs about 4% miles to the north of Arm- strong. It i s composed of sand and gravel occupying a narrow bedrock channel. T h i s aquifer trending from southwest t o northeast is about 4 miles long and 2s mile wide with a saturated thickness of up t o 200 f ee t . It has been reported by a loca l res ident t ha t i n very dry weather (1970) permanent flow i n Deep Creek occurs only where this creek cuts through the s u r f i c i a l deposits occupying this bedrock channel.

Close t o the

These deposits are known t o be 575 feet, thick (Cb3

Similar data i s not available f o r the north p a r t of the However, the wa-ter levels i n the wells, and the lake levels

It i s therefore

6.4 Groundwat,er Movement, Recharge and Discharge Areas

Figure 1 integrates the s a l i e n t findings of t h i s hydrogeological study of the north end of the Okanagan River Basin. portray a well known concept t ha t the water table i s a subdued rep l ica of the topography. l eve l contours and from the map it can be seen the movement of groundwater i s towards t h e centre of the valley. A t the water table , i n the v i c in i ty of Deep C=.eek and Fortune Cre'ek groundwater flow w i l l be to the north and to t h e soulh from the L.lpographic divide between these creeks.

The water l eve l contours

The flow of groundwater i s normal to the water-

11

12 From water l eve l o r pressure readings i n deep w e ' l l s completed i n Units D and F groundwater flow occurs to the north and south from a groundwater divide located between wells C4Z TH3 and C43 THS. seismic work, it i s known t h a t there i s a divide i n the bedrock val ley p r o f i l e between these same two wells. c rea te a ba r r i e r t o groundwater flow from the Enderby area t o the south near the bedrock val ley f loor . shown t h a t deep groundwater flow does take place to the south from the Fortune Creek valley beneath the forementioned topographh divide and towards Okanagan Lake.

Also, from

This bedrock divide w i l l a lso

From the available data :It can be

The areas of recharge to deep and shallow aquifers are the val ley s ides with the main pa r t s probably being associated with the fan depos i t s of sand and gravel f lanking the east side. charge are d i r e c t l y by precipi ta t ion, and . indirectly by underflow from t r ibu tary creeks flowing i n t o the f an deposits.

The methods of re-

The discharge areas occur i n the val ley bottom and can be divided i n t o regional and loca l categories. The l o c a l discharge area:3 occur within the fan deposits and are indicated by such discharge phenomena as flowing wells and springs. and 3 miles south of Armstmng (Fig. 1 ) . (an area of po ten t ia l a r tes ian flow) is delineated a s occurring within a narrow zone bordering Fortune and Deep Creeks. It i s considered t h a t the area of a r tes ian flow occurs approximately below elevations of 1,220 feet above sea l eve l near Enderby t o 1,175 f e e t above sea l e v e l south of Armstrong. Evidence f o r t h i s in te rpre ta t ion i s based on locations of flowing wells, and on water l eve l measurements i n non- flowing wells. above sea leve l , the water level has r i s en a s close as 1% fee t below ground surface. Evidence of extension of the area of re,gional arte- s i an flow into the Shusvap River valley is given by well C43 THS, which flows, and also by a well (Hruschak, J., personnel communication) about 4 miles up this v d l e y from which water flows from a depth of 600 f e e t .

Springs and flowing wells o c ~ x r about 1% The regional discharge area

I n w e l l c42 TH3 a t an elevation of about 1,215 fee t

Groundwater temperatures taken under Task h1 f o r the deep wells i n the Armstrong-Enderby area show one anomalously low reading of 1 lYC, C42 TH2, compared t o the other 3 wells with warm waters of about 1 7 to 2OCC (Table 1 ) . The occurrence of a narrow zone of warin waters comparable with tha t of the regional discharge area i s possible but not proved. However, the low temperature reading from C42 TH2 suggests the close proximity of the well t o recharge groundwaters. Further, this well water had the lowest t o t a l dissolved so l ids content of the deep groundwater sampled. Located only 3,500 f e e t from the entry of Glanzier Creek i n t o the main valley, i t o f fe r s 'some evidence tha t fan deposits may be a source of recharge. However, it must not be ignored tha t

13 f a u l t zones could loca l ly be an important medium of recharge. be the case fo r well C42 TH2 which occurs only about 700 f e e t from the po in t of termination i n the buried bedrock-valley wall of a f a u l t cut- t ing across Kendry and Glaneier Creeks (Fig. 1 ) .

This may

The nonpumping water l eve l of 101 f e e t i n well Ch3 TH2 was about 40 f e e t deeper than expected. The or ig ina l purpose of the tes t hole was to determine the nature of an anomolous lens detected by seismic work along the Maid Creek cross sect ion (Fig. 1 ) . water l eve l may be the r e su l t of the location of this well i n r e l a t ion to a lens of l e s s permeable material ( s i l t ) i n more permeable surrounding deposits ( f ine- to medium-grained sand) as explained by T6th (1 962). Near the upstream p a r t of a lens the difference between the o r ig ina l undisturbed po ten t i a l field and the new one gives r i s e to a negative e f f e c t on the water leve ls . the nonpwnping water l eve l than was ant ic ipated is believed t o be due to the occurrence of the well i n the v i c in i ty of the upstream p a r t of t he lens .

The cause of the low

Therefore the deeper depth to

6.5 Transmissivity Values

There is very l imited information concerning transmissivity values f o r aquifers i n the study area. The data are obtained mainly from Task 41 (Le Breton, 1972). .

Transmissivity values (Table 1 ) f o r aquifers i n the loweiv p a r t of the s u r f i c i s l deposits a r e avai lable f o r un i t s D and F. TI11 and TH3 i n u n i t F the values are conrparable, 1980 and 11 32 i g p d f t (imperial gallons per day per f o o t ) . wells (Figs. 3 and 5 ) a r e pa r t ly conparab!.e showing a period of sta- b i l i zed water levels a f t e r one l o g cycle of drawdown. In both cases s t ab i l i za t ion may be due t o p a r t i a l pcnetri t ior. whish i s similar to t h a t of recharge (Hantush, 1961). The transmissivity values shown i n Table 1 are d i f f e ren t from those on the graphs because corrections have been made f o r p a r t i a l penetration i n wells C42 TH1 i3nd TH3. The information from these two wells i s comparable (Table 1 ) with regard t o aquifer thickness, transmissivity, permeability, water temperature and water qual i ty .

For wells CL2

The pump t e s t graphs f o r both

The transmissivity value f o r well Ck2 TH2 i n Unit F is 3.4,300 i g p d f t . A similarly high f igure, 26,Loo i g p d f t was obtained f o r C43 THS i n u n i t D. t h a t f o r the other Lvio wells i n u n i t F t o the north and south. I ts considerably higher transmissivity suggests t he a r e a l extent of clean sand and gravel deposits i n the zone is l imited. de f in i t e discharge boundary condition became evident towards the end of t h e pump test. d-awdown graph. becacse the lower transmissivitjj of 2,090 i g p d f t w i l l r e s u l t i n a

The transmissivity value from w e l l C42 TH2 contrasts krith

From f igure 4 a very

This is denoted by .the s teep change i n slope of the The e f f e c t of the discharge boundary i s very important

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considerably lower well yield.

Two transmissivity figures were obtained under Task 41 f o r the upper p a r t of the s u r f i c i a l deposits. f o r C43 TH2 (Fig. 6) is obtained f o r the p a r t of the aquifer 210 feet thick above the s i l t lens. T h i s f igure is qui te comparable with that of 8S;,400 i g p d f t f o r the same aquifer 600 feet th ick encountered i n well c26 TH2 put down p r io r to this study. lgpd/ft was obtained f r o m the pump test i n well C43 "H3.

Data f o r transmissivity acquired from work under Task 41 considerably increases knowledge of the Qrdrogeology of the study area.

A transmissivity of 27,700 i g p d f t

A transmissivity of 100

6.6 Water-Well Yields (Task 41 )

The estimated well yield calculations given i n t h i s section are intend- ed to replace e a r l i e r estimates given i n previous reports.

I n the main Okanagan River Valley deep well pumping t e s t data commonly indicate low well yields (Table 1 ) from wells about 700 to 1,200 f e e t deep. pumping depths of 200 feet below ground surface to 265 igpm to the top of the aquifer f o r wells C42 TH? and TH3 i n Unit F. Also completed i n Unit F, w e l l Cb2 TH2 has a higher estimated y ie ld of 250 igpm to the top of the aquifer. However, the only r e a l l y favourable loca l i t y f o r fur thor development i s that indicated by C43 THS. The very shor t period of free flow from this well, associated with w e l l development l a s t ing f o r about 5 hours, is insuf f ic ien t t o indicate declining flow o r discharge boundaries. is the only s i t e where well yields of up t o 1,000 igpm may be obtained. Further t e s t ing is essent ia l t o substantiate this statement.

Well yields from aquifers i n the upper p a r t of the s u r f i c i a l deposita may l oca l ly be high, a s i n the Armstrong area. For a pump se t t i ng of 200 f e e t a well yield of 183 igpm f o r C43 TH2 has been calculated from Task 4l data. of 2.4 i g p m and includes a 30 percent safetg factor . factor is introduced t o allow f o r declining water levela which occur i n reality i n conjunction wi th constant pumping ra tes . a production well, C25 TH2, of a pr ior study it is s ta ted a f ie ld of about 850 igpm is possible. designed by Mr. E. Livingston. a t a pumping rate of 328 i g p m . - i c a l yield is obtained of 3,400 igpm which includes a 30 percent sa fe ty factor . a t a depth of 1 80 f e e t below ground surf ace (Fig. 17.

Yields range f r o m 1 0 igpm (imperial gallons per minute) for

However, f o r pump se t t i ngs of 200 f ee t , this

T h i s yield was derived from a specific capacity The safe ty

From data for

T h i s estimate i s made for the well as The spec i f ic capacity is about 38 i g p m Based on spec i f ic capacity a theoret-

T h i s yield is f o r drawdown to t h e to of the aquifer

The s igni f icant differences i n yield between the two we:Lls is pr i - marily due t o design. The calculated y ie ld from C43 TH2 is obtained

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16 from a tes t hole completed fo r observation-well u3e and t c ~ obtain preliminary groundwater information. as a production well and designed to operate a t a high efficiency. T h i s comparison i s made t o show tha t higher yields may be obtained from be t t e r designed wells. data may actual ly be considered a s m i n i m values.

The other well c26 TH2 was completed

Thus well yields calculated from Task 41

The "capped" w e l l near the e a s t end of the Maid Creek cross section (Fig. 1 ) had a f r e e flow of about 320 igpm from 220 f ee t . The spe- c i f i c capacity of this well is 9 iepm/ft of drawdown giving a theo- r e t i c a l yield of about 1,600 i g p m t o the top of the aquifer.

The f igures fo r the above wells do not take in to account the e f fec ts of hydrogeologicalboundaries, the e f fec ts of which w i l l be to reduce w e l l yields. to be more r e a l i s t i c .

Thus well-yield estimates of up t o 500 igpm may prove

As very l imited FnTormation is available f o r the O'Keefe t r ibu tary val ley (Fig. 1 ) l i t t l e reference has been made to this val ley SO f a r . On the basis of spec i f ic capzcity data (Table 1 ) it would appear t ha t high well yields are obtainable from the O'Keefe Valley aquifer. spec i f ic capacity declines with y i e l d (Todd, 1959, p. 111) and no data is available concerning discharge boundary conditions it is suggested that yields of 500 igpm may be obtained, and possibly 1,000 igpn.

As

I n tb narrow southwest-northeast trending bedrock channe:L aquifer extending about 4 miles to the northeast from Parkinson Lake, 4% miles northwest of Armstrong, well yields of up to 50 igpm may be obtained. A shor t t r ibu tary creek 2,000 f e e t long draining from this aquifer i n t o Deep Creek about 4% miles north of Armstrong is supplied mainly by one spring flowing a t an estimated rate of 150 igpm (Fig. 1).

6.7 Groundwater Flow Calculations

The following calculations f o r groundwater flow a re based on the data obtained from Task 41 and replace previous calculations (Le Breton, 1971). The reader should first be made aware of the limits of accuracy of the following flow estimates. it were suggested tha t the accuracy of these estimates was any be t t e r than one order of magnitude. value of each figure is unlikely t o be e i the r 10 times as m a l l o r 10 times as large as the f igure ci ted, but might l i e somewhere between these 2 extremes. (14-E) cross section (Fig. 1 ) . formation on geology and groundwater hydrology i s available.

It would be misleading i f

By this def ini t ion it i s meant the

The f igures presented below apply to the Maid Creek This is the section f o r wWich most in-

Groundwater flow was calculated by using the formula:

17

i n which Q = r a t e of flow ( i n c fs and ac.ft /yr) 2 K I A

= permeability (hydraulic conductivity) ( i n igpd/ft ) t= hydraulic gradient ( i n f t / f t ) = cross-sectional area ( i n sq.f t )

Permeability values have been derived f r o m transmissivity f igures given i n Table 1 and were obtained by dividing transmissivity by the aquifer thickness; the hydraulic gradient i s derived from differences i n water l e v e l readings i n wells divided by the distance between wlells; and the cross-sectional area is the product of aquifer thickness multiplied by the possible aquifer width.

Groundwater flow fo r the lower p a r t of the s u r f i c i a l deposits was calculated f o r the cross-sectional area "CD" of Unit F (Fig. l ) allowing fo r an aquifer thichmess of 125 fee t . groundwater flow is considered t o he the most significant,. It has the l a rges t cross-sectional area and is considered to be the zone with the highest permeability comprising sand and gravel with some silt. wa previously assumed Unit F would have a permeability of 1,000 igpd/

t e s t ing showed a figure of only 1 3.2 igpd/f t

T h i s is the zone within which

It f t 9 (imperial gallons per day per square foe$), but subsequent pump

Using the formula:

. n

where K - 1 .32 x 1 O L 3 i g p d / f t c I = 1.4 x 10L f t / f t A a 1.25 x 10" sq f t

the total underflow i s calculated a s 4.3 x 'I Om2 c fs (cublic feet per second).

Underflow f o r the upper p a r t of the s u r f i c i a l $eposits Wi3S previously calculated using a permeability of 300 igpd/ft ed protion of the aquifer of well c26 "H2. data from well C43 TH2 giving a permeability of 130 igpd/ft2 this f ig - ure is used fo r revised groundwater flow calculations. f o r that portion of the aquifer overlying the s i l t lens compares favourably with a figure of 140 igpd/ft2 f r o m well G26 TH2 having an aquifer thickness of about 600 fee t .

derived :for the screen- However, a f t e r obtaining

This figure

Using the formula:

Q = K I A 2 2 where K = 1.3 x 10 igpd/ft

I = 1.4 x lOZ3ft/ft A = 7.2 x 10 sq f t

total groundwater flow f o r the cross-sectional area ltAB't is 2.44 cfs ( 1 ,780 acf t /y r> . The combined t o t a l groundwater f lov f o r the aquifers fo r which data is available i s 2.48 c fs . The ac tua l total cross-sectional area through which flow occurs i s larger than tha t used i n the above calculations, but the remaining sediments are almost cer ta inly less permeable. Based on the presently available data, a r a t e f o r groundwater flow of about & c f s (1,825 acf t /yr) i s l i k e l y t o be a reasonable figure.

To ta l groundwwter flow toward Okanagan Lake includes tha t from the O'Keefe t r ibutary valley which enters the main valley a t ia point south of the Maid Creek cross section. tained from pump t e s t s f o r the O'Keefe Valley aquifer under Task h l . Calculations f o r groundwater flow f o r t h i s aquifer have bleen revised on the basis of exis t ing data only.

I n a previous calculation a K value of 6,000 igpd/ft screened portion of the aquifer from the f i r s t pump t e s t on a well 5,000 f e e t south of C43 TH4. f o r the permeable section of the deposits of t h i s w e l l and obtained from a l a t e r pump t e s t , i s used i n the revised calculations given below.

No permeability values could be ob-

2 was used fo r the 2 A lower f igure of about 1,000 igpd/ft ,

Applying the formula:

Q = K I A

where K = 1,000 igpd/ft 2

I = 3.7 x lO-aft/ft A = 1.26 x 10 sq f t

groundwater flow is 0.86 cf3 (625 acft/yr).

Summing the groundwater flow f o r the main valley and the O'Keefe Valley, t o t a l underflow toward Okanagan Lake is 3 1/3 cf s (2,370 acft/yr) . 6.8 Theoretical Calculation of Recharce

As some indications concerning well yields and underflow have been given, so too w i l l a theoret ical evaluation be made of recharge to the water table. This w i l l be made with regard to the map of the water- t ab l e contours, average annual precipi ta t ion fo r the weather s t a t ion near Armstrong and t h e possible area of recharge along the west and e a s t s ides of the main Okanagan Valley.

The average annual precipi ta t ion f o r the weather s t a t ion near Armstrong is 17.18 inches. between Okanagan Lake and the Shuswap River as the s i t e :is roughly

This f igure i s consLdered an average f o r the area

18

19 cen t r a l ly located. The water-table contours r e f l e c t the 'topography of t h e land surface and a s the direct ion of groundwater flow is normal to the contours, recharge i s from the val ley s ides . s teep gradients, commonly 1,000 t o 2,000 f e e t per mile much of t h e va l ley slopes are considered t o be recharge areas. of this repor t , f o r the 17 mile distance between Okanagan Lake to t h e Shswap River, a recharge width of 3 miles is taken f o r the east s i d e of the va l ley and of 1 mile on the west s ide of the valley, giving a recharge area of 68 square miles. miles is used. Also 1 inch of prec ip i ta t ion is assumed to reach the water table, a not unreasonable assumption as 1 inch of recharge is only 6 percent of the average annual precipi ta t ion.

With the ex is t ing

For the purposes

For calculation purposes, 70 square

To ca lcu la te t h e volume of 1 inch of water per square mile:

A 1 sq m i a 27,878,400 sq f t

1 inch of water per sq m i = 2,323,200 cu f t of water

B Number of seconds per 'year = 31,536,000

C Quantity of recharge of 1 inch per sq m i = 0.0736 c f s

D Quantity f o r 70 sq m i = 5.152 c f s

Some in t e re s t ing conclusions may be drawn from comparison of the groundwater flow calculations i n r e l a t ion to recharge from precipi- t a t i on . The groundwater flow of 2& c f s (1,825 acf t /yr) a t the Maid Creek cross sec t ion f o r the north end of the main-valley is w e l l with- i n the range of 5 cfs (3,650 acf t /yr) derived f r o m p rec ip i ta t ion given a recharge of 1 inch of water to a recharge area of 70 square miles. . There i s then an adequate quant i ty of recharge t o the water table t o account far the total underflow.

Similar calculat ions f o r the recharge area of the O'Keefe Valley aquifer which i s estimated to be 10 square miles is 0.74 c f s (540 a c f t /yr) o r s l i g h t l y less than the calculated underflow of 0.86 c f s (625 acf t /yr) . p o s s i b i l i t y of hydraulic continuity between the Salmon River and groundwater a t t he north end of the O'Keefe Valley aquife.r. ernmost lake has a water-level elevation of 1,480 f e e t which is about 20 f e e t below the elevation of the Salmon River occurring, 2,200 f e e t fur ther north. from the Salmon River Valley i n t o the O'Keefe Valley. formation a t t h e north end of this val ley regarding cross-sectional area and l i thology of the deposits t o calculate the r a t e fof groundwater flow i n t o this valley. Therefore i n this repor t no estimate w i l l be made of flow from the Salmon River V:zlley to the O'Keefe Valley even thotrgh it seems to be a de f in i t e poss ib i l i ty .

However, this is acceptable f o r there seems to be a de f in i t e

The north-

There is a de f in i t e prospect of movement ,of groundwater There is no in-

20 The total groundwater flow towards Okanagan Lake is about 3 l /3 c f s (2,370 acf t /yr) . f igure of 12 c fs (8,750 acft/yr). accuracy of one order of magnitude as considered l i k e l y irk the Ground- water Review Board's appraisal of an e a r l i e r progress report (LeBreton, 1971)-

T h i s stands i n contrast t o an i n i t i a l l y calculated However, i t l i e s w i t h i n a range of

4.9 Hydrogeochemis trx

The addition of e ight more chemical analyses of groundwater f o r the study area pennits some understanding of the regional picture of the groundwater chemistry. data a l so appear to provide some supporting evidence concerning sources of groundwater recharge.

These data combined with water-temperature

Completely new information was gathered under Task 41 from 4 deep wells concerning groundwaters from 2 aquifers i n the lower p a r t of the sur- f i c i a l deposits. Three of these wells are completed i n the upper uni t , Unit F, of these deposits and show the water is low i n t o t a l dissolved solids content, about 200 t o 500 ppm (parts per mill ion). The water i s primarily calcium and magnesium bicarbonate with minor amounts of sodium su l fa te . and magnesium bicarbonate-type water of 200 content and q u i t e , cool water temperature, 11-5 C, provides strong indications of receiving recharge water. The other two wells a r e s i t e d i n areas where s imilar ly deep groundwaters have undergone warming in- flugnce with temperatures from 18'8 to 2OoC. 1& C and water qua l i ty data were obtained f o r the well completed i n the middle uni t , Unit D, of the lower p a r t of the s u r f i c i a l desposits. These warm waters suggest a narrow zone of w a r m regional discharge area groundwaters occurs i n the middle of the main valley.

Well C42 TH2 with the f reshes t water quali ty, calcium m total dissolved so l ids P8

Similarly w i m water

.

Wells i n the upper p a r t of the s u r f i c i a l deposits are cormnonly very low i n t o t a l dissolved sol ids content, 150 to 180 ppm, with calcium and magnesium-bicarbonate type water. The water temperatures a re qui te cool from 1@pC t o about 13OC. The very low t o t a l dissolved sol ids content of water from the pr iva te Itcappedtt well, Kaid Creek (W-E) cross section (Fig. l ) , indicates the close proximity of the well to a source of groundwater recharge. well C42 TH2 may receive water by underflow from tributaqy creeks through fan deposits near the mouths of these creeks. I t is also possible t h a t well C42 "H2 may a l te rna t ive ly be close to a source of recharge coming from a bedrock f a u l t zone.

Both this "capped" well and

Two chemical analyses of groundwaters are available near the south end of the O'Keefe t r ibu tary valley. magnesium bicarbonate type with a total . dissolved sol ids content of 361 ppm from a depth of 192 f e e t . magnesium bicarbonate and su l f a t e water with a t o t a l dissolved solids

One well shows water of calcium and

The second well shows calcium and

. L,. _ _ : , I.

content of 588 ppm from a depth of 527 f ee t . solved so l ids content with depth i s consistent within the writer's l imited experience of such information.

I n summary, it may be s ta ted t h a t the groundwaters a re of calcium and magnesium bicarbonate type, low i n t o t a l dissolved sol ids content, commonly l e s s than 500 ppm. The water i s considered f i t f o r human consumption and commonly su i tab le f o r i r r iga t ion use. For indus t r i a l purposes the water i s of very good qual i ty and should require only l imited treatment, treatment varying according to the process for which the water i s used. some softening as the hardness commonly ranges from 120 to 160 ppm.

This increase i n d i s -

For washing clothes the water w i l l require

21

22

7. EVALUATION OF ESIJLTS

There i s very imited t e s t hole control, including pump-test data, i n the study area. T h i s i s especially so for deep test holes, which i s due to the high costs and d i f f i c u l t i e s of conducting deep-valley groundwater exploration programs. However, the quantity and qual i ty of the information available i s j u s t suf f ic ien t t o enable a regional hydroeological evaluation of the area to be carried out. .

There is j u s t su f f i c i en t water-level data f o r determination of hydrau- l i c gradients f o r some deep and shallow aquifers, thus permitting a regional interpretat ion of groundwater movement and an understanding of recharge and discharge areas. From the d is t r ibu t ion of' the pump- t e s t data, it i s possible to distinguish aquifers which loca l ly may be su i ted t o high-yield wells about 1,000 igpm, but lower yields l e s s than 100 t o 200 igpm are commonly anticipated. obtained from pumping tests make groundwater flow calculations possible. These flow values can be compared with theoret ical recharge estimates. Estimates have a l so been made fo r the determination of groundwater resources available from water mining. Possible t i m e periods required to recharge depleted resources have also been calculated. thought that reasonable conclusions concerning groundwater resources and well yields have been reached.

Information gathered on water quali ty show groundwaters, though commonly hard, a r e su i tab le f o r human consumption and i r r iga t ion , and requires only l imited treatment f o r i ndus t r i a l purposes, and f o r laundering.

The r e su l t s obtained d i rec t ly from the siesmic program (Task 39) from t e s t d r i l l i n g (Task 40) and pumping tests (Task 41) were good. It has been demonstrated that seismic programs a r e a valuable preliminary phase in deep-valley groundwater exploration s tudies f o r planning test dr i l l ing . ing t e s t s f o r aquifer evaluation.

The permeability values

It is

?

Test d r i l l i n g alone is inadequate without subsequent pump-

It can be s ta ted t h a t the importance of groundwater resources re la t ive t o surface water resources or surface water development programs can be readily assessed. This can be done even though t h e ac,tual quantity of groundwater available f o r development on an annual o r water-mining basis may have been considerably underestimated. Howsver., it becomes apparent t ha t groundwater resources are not a feasible a l -hrna t ive to large scale development of surface water resources.

23

8. POTENTIAL GROUNDWATER DEVEIQ PFENT

From groundwater flow calculations and a theoret ical calculation of groundwater recharge from precipi ta t ion, the poten t ia l groundwater resources available f o r development without depleting groundwater resources range between 3 1/3 and 6 c f s (2,370 to 4,380 a c f t per year). This i s equivalent t o wells continuously producing a total of 1,120 t o 2,240 i s m . It is very unlikely that groundwater withdrawal takes place i n the study area a t this r a t e a s the number of high producing wells, i n excess of 100 ism, is very small. there i s scope f o r l imited increase of groundwater resources.

On t h i s basis alone

8.1 Lower Par t of the Surf ic ia l Deposits

From the exis t ing pump-test data, there appears to be l i t t l e prospect f o r considerable development of groundwater supplies from deep wells, t ha t is, about 1,000 f e e t deep. The exception is the aquifer encountered about 800 to 875 f e e t deep (C43 THS) near Enderby. T h i s p a r t of the study area probably falls en t i r e ly within the hydrologic regime of the Shuswap River Valley Drainage Basin, and i s not considered as p a r t of the Okanagan River Basin hydrologic budget. groundwater development increases s l i gh t ly when the Enderby area is considered, but the scope f o r development here is not known. promise i s an area of a r tes ian flow extending about 4 mi:les up the Shswap River Valley from Enderby (Fig. 7 ) . points upon which this statement i s based are two wells 14 miles apart. One of these wells is C43 THS over 800 f e e t deep and the other i s reported to be 6 ~ 0 feet deep. both terminate i n the same o r i n d i f fe ren t aquifers. f u l l y evaluate groundwater po ten t ia l i n the v i c in i ty of Enderby, fur ther information i s required concerning the a rea l extent of deep aquifers. duction wells including observation wells, so that adequate aquifer t e s t s can be conducted f o r the purpose of determining not only w e l l y ie lds but well spacing. It is the wr i te r ' s opinion that well yields of up t o 1,000 igpm a r e a poss ib i l i t y i n t h i s p a r t of the study area. However, the lack of information on the proximity of l e s s permeable boundaries and the i r attendant e f f e c t i n reducing well yields i s unknown. ploration is def in i te ly ju s t i f i ed .

The poten t ia l fo r

Of some

However, the two control '

It i s not known whether these two wells I n order t o more

This information must be supplemented by deep test-pro-

The loca l i t y is certainly one i n which fur ther groundwater ex-

Elsewhere i n the main Okanagan River Valley it appears that well yields from deep aquifers i s disappointingly low, l e s s than 250 igpm fo r pump se t t ings of 200 f ee t . t o the top of the aquifer. indicated by data collected from deep aquifer pumping tests, there is insuf f ic ien t evidence to believe that groundwater potent ia l occws f o r

Progressively higher yields would be obtained Though minimum well yields a re believed

50' :

LEGEND

I - I 151 PARKINSON LAKE BEDROCK CHANNEL AQUIFER IIIII INDIAN RESERVE BDY.

. m u m - * m * . = DISTRICT MUNICIPAL BOUNDARY

I 4 I O'KEEFE VALLEY AQUIFER

131 UPPER PART OF SURFICIAL DEPOSITS -FAN DEPOSITS

12 I UPPER PART OF SURFlClAL DEPOSITS-VALLEY CENTRE

FIGURE 7 AREAS INDICATED FOR

m7nI IhlnUlATCD FYDl nDATlnN

24 l i t t l e more than domestic and farm livestock watei. supply requirements. Again tes t production wells including one observation well a r e necessary t o improve on present knowledge of t he study area. design problems and costs of 1,000 f e e t deep wells are a de ter ran t t o fu r the r evaluation of apparent low yield areas.

However, wel l

8.2 Upper Par t of the S u r f i c i a l Deposits

The chief source of groundwater supply i n the main Okanagan River Valley i s the area t o the south of Armstrong (Fig. 7 ) . Within t h i s l o c a l i t y w e l l y ie lds of up to 850 i e p m can de f in i t e ly be otained near the centre of t he val ley and possibly higher yields . However, con- d i t ions imposed by well design problems and costs w i l l limit yields i n pract ice , though figures of 3,500 igpm seem t o be a theore t ica l poss ib i l i t y . due t o impermeable boundaries which w i l l reduce well yields . The ex ten t of the aquifer, mainly f i n e grained sand with some silts is no t known bu t it ranges i n depth from about 200 t o 800 fee t below ground surface. 41 data suggest minimum well y ie lds of about 200 igpm (C4.3 TH2) from this aquifer.

These calculations do not take i n t o a c c o a l imitat ions

The aquifer i s therefore about 600 feet ‘thick. Task

Within the same area to the south of Armstrong (W-E cross Section Fig. 1 ) near the east s ide of t he val ley are two flowing wells. designated as CW -(capped well) had a free flow of 320 igpm and a theore t ica l yield of about 1,600 i g p m is a poss ib i l i ty . effect of dischayge boundaries i s unknown. However, an estimated well y i e ld of 500 i g p m may be reasonable. deposit believed t o be associated w i t h fan deposits f lanking the east val ley wall, is known t o be a t l e a s t 50 fee t thick. I t s a rea l extent (Fig. 7) is not known, but probably does not extend fa r to the west beyond the 1,300 feet contour l i n s . The convex shape of the topograph- i c contours probably indicates much of the a r e a l extent of the f an de- p o s i t s flanking the e a s t val ley wall. Their westward extent may not always be delineated i n terms of topographic expression and there is i n su f f i c i en t d r i l l hole control to determine the i r actual extent.

The well

Again the

The aquifer, a sand and gravel

About 3 miles south of Armstrong are 2 other flowing wel1.s capable of producing about 100 igpm o r possibly more. These a re associated with a fan deposit of la rger areal extent than tha t of the fan deposit d i s - cussed above. s ib le y ie lds which may be ant ic ipated from wells associated with these fan deposits. the significance of recharge by underflow to these f an deposits from t r ibu ta ry creeks flowing i n t o them.

Well data f o r the 2 fan deposits give an idea of pos-

What is unknown i n terms of groundwater po ten t ia l i s

It can be seen from a study of the i n s e t map of the surfj-cia1 geology (Fig. 1 ) and topographic contours tha t fan deposits occur along much of the east val ley wall. Prospecting for groudwater within these

deposits followed by t e s t pumping is encouraging a s denoted by well y ie lds f o r a very few wells.

There are a l so some thin, minor o r l oca l ? sand deposits contained i n the c o m n l y thick s i l t deposit which comprises the majority of the upper part of the s u r f i c i a l deposits of the main valley. Thick loca l

sands shown on the north-south cross section (Fig. 1 ) a r e presumed to be of importance as only supplying small water supply requirements f o r domestic or l ivestock purposes.

8 . 3 0 'Keefe Valley Aquifer

Information regarding poten t ia l groundwater resources is very l imited and avai lable only f o r the south end of the valley. It does indicate high capacity wells from sand and gravel deposits up t o 576 f e e t deep with a saturated thickness of about 350 f ee t . Theoretical w e l l y ie lds of up to 2,850 igpm seem to be a poss ib i l i ty . Because of the influence of discharge boundaries, about which there i s no data avai lable a t present, w e l l yields a re estimated to be i n tho range of Sol0 to 1,OOOigpm.

There is no information regarding the areal extent and saturated thickness of the sand and gravel deposits throughout the valley. from the map of the s u r f i c i a l geology and apparent continuity of the water leve ls i n wells with that of lake levels t o the north end of the valley, it is believed the aquifer is continuous from the Salmon River Valley to Okanagan Lake (Fig. 7) .

However,

On the bas i s of p rwen t knowledge of the hydrogeology of the O'Keefe Valley, it is def in i te ly jus t i f ied to conduct fur ther groundwater ex- plorat ion programs within this valley.

8 e4 Parkinson Bedrock Channel Aquifer

The only remaining l o c a l i t y of significance i n terms of groundwater PO- t e n t i a l i s a narrow, sand and gravel aquifer about 4 miles long extending to the northeast from Parkinson Lake (Fig. 7 ) . It occurs a t an elevation j u s t below 1,700 f e e t above sea level. about 250 feet thick with a saturated thickness of 200 f e e t . y ie lds based on pump test data from one well a r e estimabed t o be 50 igpm o r s l i g h t l y higher. Spring d i sch rge , from a point 4:s miles north of Armstrong, forming a very shor t permanent t r ibu tary 'to Deep Creek has a discharge of about 150 i g p m . At the point where Deep Creek flows from i t s course across this bedrock channel aquifer, its flow i s r epor t - ed to be permanent. above this bedrock channel aquifer, according t o one loca l resident.

The sand and gravel is Well

In %rought" years such a s 1970 Deep Creek is dry

The above information suggests t ha t there i s l imited scope fo r

26

L

t

groundwater development i n t h i s p a r t of the study area. f l o w within this bedrock channel aquifer a short distance ves t of Parkinson Lake i s considered to flow in to the Salmon River and so falls outside the Qdrologic regime of the Okanagan River Basin.

I n summary, the main sources f o r groundwater withdrawal i n the study area are aquifers i n the upper p a r t of the s u r f i c i a l deposits and the O'Keefe Valley aquifer. part of the Maid Creek cross section, a s fan deposits along the eas t val ley w a l l , and probably throughout the e n t i r e length of the O'Keefe Vallcy. There is a l so a sand and gravel bedrock channel aquifer 4% miles north of Armstrong with l imited poten t ia l fo r groundwater development, and loca l ly as a t Enderby, there is some prospect f o r high yield wells from deep aquifers.

Groundwater

These aquifers occur mainly i n t,he central

8.5 Groundwater Mining

A t o t a l groundwater withdrawal capacity of 2,240 igpm without depleting the resources seems to be low. c ip i ta t ion reaching the water tab le over the e n t i r e recharge area. However, the quantity of recharge by underflow from t r ibu tary creeks i n t o . f m deposits i s not known. There is evidence to suggest tha t moderate quant i t ies of runoff water may be l o s t to underflow along the porous and permeable sand and gravel beds of t r ibu tary creeks, such as Vaseawc Creek (Fig. 2) . from prec ip i ta t ion does not include any additional increments t o groundwater resul t ing from i n f i l t r a t i o n from stream runoff. unknown fac to r i s the amount of water moving from the Sa:Lmon River into the O'Keefe Valley. prove t o be s ignif icant , the poten t ia l f o r groundwater development . would increase.

This is equivalent t o one inch of pre-

The calculation of recharge to groundwater

Also an

I f both the l a t t e r methods of recharge should

I f the concept of groundwater mining is considered the following recoverable water quant i t ies have been estimated to be available f o r withdrawal. The reader i s reminded, as i n the case of groundwater flow calculations, that the limits of accuracy are ant ic ipated to be no closer than one order of magnitude.

Aauif e r s Acre feet - Upper Par t of Su r f i c i a l Deposits

Lower Part of Sur f i c i a l Deposits

5,000

1,500 60 , 000

66 , 500

(south of Armstrong on ly )

0 'Keefe Valley

I n arr iving a t the quant i t ies of water available f o r mining the following f igures were used:

Aquifer Length Width Thickness Effective Porosity ( f t ) ( f t ) ( f t ) s%

Upper p a r t of

Lower p a r t of Surf i c i a l Deposits

S u r f i c i a l Deposits 34,000 10,000 600

Unit F !&,OOO 6,000 125 Unit D 30,000 5,000 125 U n i t B 30,000 3,500 125

0.1

0.1 0.1 0.1

0 'Keef e Valley 30,000 3,000 200 1 5:

The above f igures f o r groundwater mining are estimates based on l imited information of the geology of t h e area. the physical dimensions of an extensive 3-dimensional body, to estimate the proportion of its volume occupied by aquifers and to ar r ive a t values fo r the hydrologic properties of these aquifers , u t i l i z i n g a few ra the r widely spaced t e s t holes and some seismic information. fu r the r improve knowledge of the geology and consequently of the ex- t e n t , thickness and l i thology of individual aquifers considerably more test d r i l l i n g i s essent ia l .

The problem is to determine

To

As an example of the l i m i t s of accuracy of groundwater avai lable f o r mining i f the f igure of 5,000 acre f e e t for the upper p a r t of the s u r f i c i a l deposits i s considered, the quant i ty of recoverable water ranges from 500 to 50,000 acre feet. of magnitude. Valley aquifer where t h e estimated upper l i m i t f o r recoverable groundwater supplies may be considerably less than one order of' magnitude.

This i s the range for one order The exception to the above f igures i s the O'Keefe

Based on an annual rate of recharge from prec ip i ta t ion of 1 inch which is equivalent to 5 c f s (3,600 a c f t per year) f o r the main val ley it would take about 2 years t o replenish the quant i ty of water taken f r o m storage by mining aquifers i n the lower and upper p a r t s of the sur- f i c i a l deposits. I f recharge to the lower and upper p a r t s of the sur- f i c i a l deposits are considered separately it would take 3 years to replenish the upper p a r t based on a groundwater flow r a t e of 2.44 c fs (1,780 a c f t per year) , but very many years t o replenish the lower pa r t .

I n the O'Keefe Valley with a recharge rate of about 0.74 cfs , equiva- l e n t to about 540 acre f e e t per year, it would require 110 years t o replenish groundwater r c souxes taken from storage. p o s s i b i l i t y of limited underflow from t h e Salmon River Valley the period of time necessary for recharge would be reduced.

However, with the

27

28

9 . ECONOMICS OF GROUNDWATER DEVELOPPENT

The economics of groundwater development f a l l i n to 2 main categories. One is preliminary exploration, the other is the cap i t a l costs of production wells. downwards due to varying geologic conditions e tc .

Actual costs given below might range 20% upwards o r

9.1 Costs of Groundwater f o r High-Yield 'Wells

Preliminary exploration costs f o r a specif ic l oca l i t y may include costs f o r both seismic and t e s t d r i l l i ng . o r two prof i les including consultant's fees a re estimated t o cost about $5,000 to $10,000. Costs of 2 rotary t e s t wells about 1000 f e e t deep including 24 hour pumping t e s t s a re estimated t o be about $35,000 but these costs do not include consulting fees. water exploration costs could be about $4S,OOO.

A seismic survey comprising one

Total preliminary ground-

The costs of production wells a re estimated separately f o r the O'Keefe and the Okanagan Valleys. The capi ta l costs of production wells, including pump and well housing, t o produce groundwater supplies a t 4 acft/day (acre f e e t per day) f o r 90 days could range from about $25,000 f o r a well 225 f e e t deep near the north end of the O'Keefe Valley t o about $36,000 f o r a w e l l 425 f e e t deep near t he south end of the valley. water treatment, nor consultant's fees. Estimated annual. costs a t the well head fo r the foregoing production wells, with a power cost of 60.54 per acft/day f o r the former well and of $2.45 per aeft/day fo r the l a t t e r well, a re given below. These annual costs do include in- terest and amortization, and operation and maintenance costs over a period of 25 years a t i n t e r e s t r a t e s of 5%, 7% and 9%.

These costs do not include bringing power tC1 the si te,

( A ) $25,000 w e l l

Amortization costs per annum

Power costs f o r k ac f t p e r day f o r 90 days Operation and Maintenance

In t e re s t r a t e s f o r 25 years

5% 7% 9% $ 1,770 $ 2,145 $ 2,510

$ 218 $ 218 $ 218

$ 1,250 $ 1,250 $ 1,250

Total annual costs fo r one well producing 4 ac f t per day fo r 90 days

Total 25 year costs $ 3,238 $ 3,613 $ 3,976 $60,900 $90,200 $!39,400

29 (B) $36,OOC well

Amortization costs per annum Power costs f o r 4 ac f t per day f o r 90 days

Operation and Maintenance

I n t e r e s t r a t e s f o r 25 1 .I ears

5% I 7% 9% $ 2,555 8 3,090 9; ,39600

$ 882 $ 882 $ 882 $ 1,860 $ 1,860 $ 1,860

To ta l annual costs f o r one well producing 4 ac f t per day fo r 90 days Total 25 year costs

The total annual costs per acre f t per day including power costs, in- t e r e s t and amortization costs over a period of 25 years a t t i n t e r e s t r a t e s of s$, 7% and 9% a re estimated to be within the following limits:

In t e re s t r a t e s f o r 25 years ( A ) Lower Limit $ 8.87 $ 9.89 $10.90

(B) Upper L i m i t $14.5'2 $15.98 $1 7 37

Production w e l l costs i n the Okanagan Valley lying north of Okanagan Lake can be expected t o vary considerably depending upon depth, condi- t ions encountered during well dr i l l i ng and upon well construction. Capital costs f o r a well approximately 1000 f e e t deep producing 4 acf t / day f o r 90 days a re estimated t o range from $25,000 to $!;O,OOO. Again these costs include pump and well housing, but do not include those of bringing power to the s i t e , water treatment, nor consultant 's fees. Estimated annual costs fo r the above wells a t the w e l l head covering power costs of $2.45 per acft/day, i n t e r e s t and amortization costs f o r a period of 25 years a t i n t e r e s t r a t e s of s%, 7% and 9% are given below.

( A ) $2'5,000 well


Power costs f o r 4 ac f t per day f o r 90 days Operation and Maintenance

Total annual costs for one w e l l producing 4 ac f t per day f o r 90 days

Total 25 year costs


5% 7% 9% $ 1,770 $ 2,145 $ 2,510

$i 882 $ 882 $ 882 $ 1,250 $ 1,250 $1,250

$ 3,902 f 4,277 9; 4,642 $97,500 $16,900 $116,000

i (B) $50,000 well

In te res t r a t e s f o r 25 years

5% 7% 9% Amortization costs per annum $ 3,540 $ 4,290 $ 5,020

Power costs f o r 4 ac f t per day for 90 days $ 882 $ 882 $ 882 Operation and Maintenance $ 2,500 $ 2,500 $ 2,500

Total annual costs f o r one well producing 4 ac f t per day f o r 90 days $ 6,922 $ 7,672 $ 8,402 Total 25 year costs $173,100 $193,800 $210,000

The t o t a l annual costs per acre f t per day including power costs, in- t e r e s t and amortization costs over a period of 25 years at, i n t e r e s t r a t e s of s%, 7% and 9% are estimated to be within the foU.owing l imits :

In t e re s t r a t e s fo r 25 years

5% 7% 95 ( A ) Lower Limit $10.69 $11.70 $12.71

(B) Upper L i m i t $18.96 $21.02 $23.00

The foregoing figures represent approximate costs of water i n acre f e e t per day. given above. Ultimately the costs of groundwater supplies will be determined by well yie ld , the demand f o r water made upon a given w e l l according t o its use ( f o r i r r iga t ion supplies f o r p a r t of a year, o r f o r indus t r ia l supplies t ha t are continuous year round) i n re la t ion to the actual costs of a well.

However, well costs may vary considerably from those

9.2

Costs f o r water supply requirements up t o 10 igpm f o r private domestic and livestock purposes w i l l be considerably lower. However, the costs of developing groundwater from deep aquifers would make such wells very uneconomic.

Low yield wells coq le t ed i n the depth range from 100 to 250 f e e t are estimated t o cost about $L,OOO t o $6,000. f o r the pump and well housing but exclude power in s t a l l a t ion etc .

Cost of Grolrndwater - fo r Low-Yield Wells

These costs include those

(B) $50,000 w e l l


Power costs f o r 4 ac f t per day f o r 90 days Operation and Maintenance


5% 7% 9% $ 3,540 $ 4,290 $ 5,020

$ 882 $ 882 $ 882

$ 2,500 $ 2,500 $ 2,500

Total annual costs for one well producing 4 ac f t per day for 90 days Total 25 year costs

$ 6,922 S 7,672 $ 13,402

$1 73,100 $1 93,800 $21 0,000

The t o t a l annual cos ts per acre f t per day including power costs, in- t e r e s t and amortization costs ,over a period of 25 years a t i n t e r e s t r a t e s of s$, 7% and 9% are estimated to be within the following limits:

( A ) Lower L i m i t

I n t e r e s t r a t e s f o r 25 years

5% 7% 9% $1 0.69 $1 1 JO $1 2.71

(B) Upper L i m i t I . $18.96 $21.02 $23.00

The foregoing figures represent approximate costs of water i n acre feet per day. given above. Ultimately the costs of groundwater supplies will be determined by well yield, the demand f o r water made upon a given well according t o its use ( f o r i r r i g a t i o n supplies f o r p a r t of a year, o r f o r i ndus t r i a l supplies t h a t a re continuous year round) i n r e l a t ion to the ac tua l costs of a well.

However, well costs may vary considerably from those

9.2 Cost of Groundwater f o r Low-Yield Wells

Costs f o r water supply requirements up t o 10 igpm f o r pr ivate domestic and l ivestock purposes will be considerably lower. However, the costs of developing groundwater from deep aquifers would make such wells very uneconomic.

Low y ie ld wells completed i n the depth range from 100 to 250 f e e t are estimated to cost about $4,000 to $6,000. for the pump and well housing but exclude power i n s t a l l a t i o n etc .

These costs . include those

10. CONCLUSIONS

The s u r f i c i a l deposits i n the north end of the Okanagan River Basin a re primarily f ine grained, low permeable materials, mainly s i l t and f ine- grained sands. pos i t s of sand and gravel. The fine-grained materials a re expected to have permeability values of l e s s than 10 igpd/ft2 and the coarser grained materials peraeabi l i ty values commonly of 100 to 300 igpd/ft

There a re some coarser grained, high permeable de-

Me11 yields fo r aquifers i n the study area a re commonly expected t o be l e s s than 200 i g p m f o r pump se t t ings of 200 f e e t . y ie lds of up t o 500 igpm or possibly 1,000 igpm may be obtained. Aquifers with well yields i n the 200 to 500 i g p m range, a r e considered t o occur i n the O'Keefe valley; and i n the main val ley i n a l o c a l i t y j u s t south of Armstrong and i n pa r t s of fan deposits along the eas t valley wall. Well yields of up t o 1,000 igpm may possibl:y be obtained near Enderby and a l so i n the O'Keefe valley, but more adequate tes t ing is essent ia l to ver i fy these high yields.

Locally higher

The quantity of groundwater available from water mining is estimated to be about 66,500 acre f ee t , most of which would be obtained from the O'Keefe Valley aquifer. the more permeable materials i s calculated t o be about 3 1/3 c f s (2,370 acf t /yr) . I This figure is considered t o be a reasonable e s t i - mate when compared to to t a l theoret ical recharge r a t e of 6 c f s (b,380 acf t /yr) obtained from 1 inch of precipi ta t ion f o r a recharge area of about 80 square miles. 100 years to replenish the water supplies t ha t could be mined from the O'Keefe Valley and only 2 years t o replenish supplies i n the main val ley aquifers. However, the poss ib i l i t y of higher recharge to the above aquifers by underflow from t r ibu tary creeks to the main val ley and from the Salmon River i n to the O'Keefe Valley is a d i s t i n c t possi- b i l i t y .

Groundwater flow towards Okanagan Lake f o r

. ,

A t t h i s r a t e of recharge it would take about

The poten t ia l f o r groundwater develo ment without depleting the resources is estimated to be from 3 1 P 3 to 6 cfs . It is unlikely tha t t o t a l groundwater withdrawal is close t o the lower value, s o there is l imited scope f o r increasing t h e use of groundwater resources i n the study area. adjacent Shuswap River Basin i s considered, then the poten t ia l f o r groundwater development increases. i 3 unknown.

If the potent ia l of the Enderby area, which occurs i n the

The possible extent of the increase

Analyses of groundwaters sampled i n the study area show the chemical qua l i ty of the water is very good. of water i s commonly i n the range of 200 to 500 ppm and the water i s primarily calcium and magnesium bicarbdnate. able f o r human consumption and f o r i r r iga t ion use and should require

The t o t a l dissolved sol ids content

The water i a qui te su i t -

32 only very l i t t l e treatment for indus t r ia l purposes.

The hydrogeological study comprising t h i s report has been confined almost en t i r e ly to the north end of the valley, the exception being a deep test hole and seismic work near Okanagan Fa l l s i n the south end of the val ley and some sub-basin studies. To bring other p a r t s of the Okanagan River Basin to the same stage of knowledge a s t h a t of the north end would require implementing some o r all of the following work items. involved and the funds available:

The d e t a i l involved would depend on the scope of the projects

1.

2.

3 .

L.

5. 6 .

7. t a 8.

Collection, tabulation, study and plot t ing of available data.

Review of relevant groundwater and geological maps and reports of the area.

Synthesis of this data i n t o preliminary Qdrogeological maps.

Hydrogeological mapping and well inventories to f i l l important gaps lacking information.

Collection of water samples f o r hydrogeochemical studies.

Geophysical studies:

Rotary tes t hole d r i l l i n g t o evaluate geophysical results; case the holes f o r preliminary groundwater information and f o r use as observation wells.

Cable t o o l t e s t production wells and pump t e s t s .

seismic and gravity meter studies.

Long range s tudies t o fur ther evaluate groundwater resources, movement and recharge are a natural follow-up to the present preliminary studies conducted p r io r to and as p a r t of the j o i n t Canada-British Columbia Okanagan Basin Study Agreement.

i -

11. REFEKENCES

Canada. Deparbent of Mines and Technical Surveys, Geographical Branch (1 957) : Atlas of Canada.

N t o n , R. J. (1 969) : Surf ic ia l Geology, Shuswap Lake, Br i t i sh Columbia

. . . . . . . . . . . . . . . . (1 969) : Surf ic ia l Geology Vernon, Br i t i sh Columbia

Geol, Surv. Can., Map 1 2 m .

.Geol. Surv. Can., Map 1 245A.

Halstead, E. C. (1 969) : Groundwater Investigation, Mount Kobau, Br i t i sh Columbia; Inland Waters Branch, Department of Energy, Mines and Resources, Tech. B u l l . Series No. 17.

Hantush, M. S. (1961): Aquifer Tests on Par t ia l ly Penetrating Wells; Jour. Hydraulics Div., Proc. Am. SOC. C i v i l Engineers, Vol. 87 No. HYS, Sept. 1961, Part I, pp. 171 - 195.

Holland, S, S. (1 964) : Landforms of Br i t i sh Columbia, A Physiographic Outline; Br i t i sh Colunbia Department of Mines, Bull. No. 48.

Jones, A. G. (1959): Vernon Map-Area, Br i t i sh Columbia; Geol. Surv. Can. M a . 296.

Le Breton, E. G. (1971): Canada-British Columbia Okanagan Basin Study Agreement : A Hydrogeological Reconnaissance Study of t,he Okanagan River Basin, Progress Report No. 1 ; Water Investigaticlns Branch, Water Resources Service, Br i t i sh Columbia Department of Lands, Forests and Water Resources.

. . . . . . . . (1 972) : Canada-British Columbia Okanagan Basin Study Agreement: Task No. 41, Cleaning, Development, Tcst-Pumping and Instrumentation of Test Holes d r i l l ed under Task No. 40 and completed f o r Observation-Well Purposes; Water Investigations Branch, Watcr Resources Service, Br i t i sh Columbia Department of Lands, Forests and Water Resources.

Nasmith, H. (1962): Late Glacial History and Surf ic ia l Deposits of the Okanagan Vzlley, Bri t ish Columbia; Br i t i sh Columbia Department of Mines, Bull. No. 46.

Todd, D. K . (1 959) : Groundwater Hydrology; John Wiley and Sons, New York .

Tbth, J . (1962)': A theory of groundwater motion i n m a l l drainage basins in Central Alberta, Canada; Jour. Geophys . Res. ; Vol. 67, pp. 4375 - 87.

33

31r

APPENDIX A

OKANAGAN VALLEY

sEIs1ac SURVEY

REVISED FINAL REPORT

FEBRUARY I , 1971

R.M. LUNDBERG P. Eng.

. . . . . . .. .4_.... .-. . . .

35 TABLE OF CONTElRS

Page

Conten~................................................. 35

I n t r o d u c t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ~ . . . . . . . . . . . . 36

Discussion of results of 1970 test hole program.......... 36

Conclusions.............................................. 39

ILLUSTRATIONS After page

40 40

40

Figure 1 Seismic l ines 1 , 2 and 3 Figure 2 Seismic l ines 4, 5 and 6 Figure 3 Location of seismic l ines , North End

Okanagan River Basin

40 Figure 4 lacation of siesmic l ines , South End Okanagan River Basin

TABLFS L___

37 Table No. 1 Percentage Error i n Prognoses

I .

APP'ENDIX A

OKANAGAN VALLey

S E I S M I C SURVAY

=SED FINAL REPORT R. M. LUNDBERO, P. Eng.

INTRODUCTION

T h i s revised repor t was prepared i n order t o incorporate the new data avai lable a s a r e s u l t of the nine hole d r i l l i n g program car r ied out i n the autumn of 1970.

The seismic data has been reviewed and i n places re- intsrpreted t o provide a combined geological-geophysical picture which is c,ompatible with a l l the data. For this purpose, revised seismic re f rac t ion pro- f i l e s and re f lec t ion sections have been prepared. age e r ro r i n prognoses is presented. on the Geologic Survey of Canada program are indicated on the seismic re f rac t ion prof i les .

A t ab le of percent- Predicted bedrock depths based

DISCUSSION OF RESULTS OF 1970 TEST HOLE PROGRAM

The seismic p ro f i l e s have been revised on the bas i s of t h e following c r i t e r i a :

1 . New t e s t hole data.

2. Revised re f rac t ion interpretat ion. 3. Revised r e f l ec t ion interpretat ion.

Table Number 1 was prepared to focus a t ten t ion on problem areas. l i m i t of e r ro r expected on this pro jec t was 2 10%. ceeded, it i s l i k e l y that the basic assumptions made i n the calculation a r e incorrect. reasonable explanation. a more de ta i led r e f l ec t ion in t s rprg ta t ion which was a major f ac to r i n revis ing the seismic refract ion prof i les .

The Where this is ex-

I n a l l cases, a review of the data has provided a I n par t icu lar , the new t e s t hole data allowed

.

37

PERCENTAGE ERROR IN PROGNOSES

HOLE - Deep Hole 1

Deep Hole 2

Deep Hole 4

Test Hole 1

Test Hole 2

Test Hole 3 Test Hole 4

Test Hole 5

CONTACT PREDICTED ACTUAL $ ERROR

Bedrock 1,645 Gravel 880

(Base of t i l l ) Bedrock 800+

'Quartzite It 1,227

Gravel 105 Bedrock 475 S i l t 430

880 Base oxidized zone 200

Bedrock 51 0 Bedrock 650

The following br ie f discussion of each prof i le the basis f o r revision i n each caser

800+ 0%

85 -24% 95 -500%

440 + 2% 415 7 -1lM 7

200 0%

540 + 7% 872 +E$

should serve t o explain

LINE 1

Three t e s t holes d r i l l e d on this l i n e showed a wide range of accuracy i n the seismic prognosis. Test Hole No. 1 , a t Stat ion 5 , encountered gravel only 20 f e e t shallower than predicted, but an incorrect seismic interpret ive assumption together with an inaccurate extrapolation of surface dips of the valley wall l ed to a large error i n bedrock depth calculation.

I n Test Hole No. 2, a s i l t layer correlated very w e l l wi th the 6,000 f t /sec. layer noted on the seismic refract ion prof i le . report postulated a th in layer which seems t o be the case as the log reverts t o sand a f t e r 70 f e e t of s i l t .

The i n i t i a l

Deep Test Hole No. 1 encountered a hard shale o r till at, the predicted bedrock level. which masks the t rue bedrock. shows the bedrock t o be 230 f e e t deeper i f an average seismic velocity

It is l i k e l y tha t t h i s bed i s a refract ing interface A deeper event on the re f lec t ion section

38 of 7,500 f t / sec f o r the 230 foo t in te rva l is use6 (a rea'sonable assump- t ion from the hole log ) . A strong re f lec t ion not interpreted previous- l y ties to t h e gravel. gravel re f lec t ion i s i ts absence a t Stat ion 102, i n proximitj t o c23 TH 1 . ing tha t a discontinuous sand-gravel interface does e x i s t a s shown on the seismic refract ion prof i le .

One observation tha t gives credence t o t h i s

north of S ta t ion 98. No gravel was logged i n t h i s well, imply-

LINE 2

Two t e s t holes were d r i l l ed on t h i s l i ne . Stat ion 40 ver i f ied the predicted gravel-sand sequence and h i t bedrock below the deepest refract ing interface as predicted. The l'quartzite" logged i n the Enderby No. 1 Well l i k e l y is the white sand and s i l t y sand reported below the till. As was the case on Line 1 , it is l i k e l y tha t the till a t 1 ,150 f e e t is a refractor which masks the bedrock re- f rac t ion i n the deeper p a r t of the valley. t i on 35 correlates with the bedrock.

Deep Test Hole No. 2 a t

A deep re f lec t ion a t Sta-

Test Hole No. 3 h i t bedrock 440 f e e t above the predicted level . A review of the refract ion p lo ts reveals good evidence f o r a high velocity (10,000 f t / sec) layer extending from Station 101 t o 67. from Stat ion 69 west lire a typical f o r the area but w i t h no re f lec t ion o r geological data, a simplified interpretat ion was made i n i t i a l l y . Whether the bedreck.logged is a thin s t r inger or detr i ta l . o r a mound- l i k e mass of d e t r i t a l and gravel i s not determinable, however, there is a good chance t h a t it is not the t rue bedrock.

The p lo ts

LINE 3

Test Hole No. 5 found the bedrock 220 f e e t deeper than predicted. I n t h i s instance, a recomputation of the bedrock depth using the c r i t e r i a used i n recalculat ing the e a s t end of Line 1 , provides a t i e with the bedrock which i s confirmed by a deep ref lect ion.

Note t h a t this l i n e was shot by the G.S.C. and tha t t h e i r prognosis was 140 f e e t low, or -16%. veys a t t h i s point i s related t o the f a c t t h a t this i s the deepest, narrowest portion of the valley surveyed.

I t h i n k the re la t ive inaccuracy of both sur-

The main reason I do not a t t r i b u t e the e r ror t o a masking e f f ec t by the till logged is tha t , unlike the data on Lines 1 and 2, the seismic data on Line 3 can be reinterpreted t o yield a deeper bedrock. this i s the case, I think it more l ike ly tha t the bedroc:k i s indeed the re f rac t ing interface.

Where

39 LINE &

Test Hole No. 4 (Station 16) ver i f ied the seismic in te rpre ta t ion very well. The 200 foot thick low veloci ty determined a t the nearest con- t r o l point (Stat ion 22) correlates wi th the oxidized sand. was found within the expected limit of error.

The bedrock

Deep Test Hole No. 4 hit conglomerate 40 f e e t below the predicted bedrock. With the hole d r i l l e d off the seismic l i n e and the various ex- trapolations that are possible from surrounding control points, it is l i k e l y that the bedrock is very close t o the predicted level .

CONCLUSIONS

The seismic survey appears t o have been reasonably accurate on the cent ra l portions of Lines 1 and 2, Line 4, and Line 5. On the flanks of the valley, steep dips, e r r a t i c gravel deposits and poorer seismic control combine to make interpretat ion more hazardous. However, we are l i k e l y more concerned with the deeper sections of the val ley f o r purposes of the t o t a l program.

By careful ly combining geological and seismic data the seismic in te r - pretat ion is f o r t i f i e d . It can be anticipated t h a t addi t ional d r i l l - ing i n the area would show more overa l l accuracy i n the revised pro- f i l e s than was found i n the i n i t i a l program. I n par t icu lar the re- f l ec t ion sections a re more understandable and y i e ld more predictive information.

The degree to which the program has been a success and the advisabi l i ty of using more seismic i n the future must be defined i n terms of the objectives of the program. With the exceptions noted above, the bedrock val ley p ro f i l e was i n general successfully predicted. The other a i m , t o determine the l i thology of val ley f i l l deposits, was achieved i n some places. The s i l t lense detected by Line 1 re f rac t ion data and ver i f ied by Test Hole No. 2; the gravel-sand sequence predicted by Line 2 re f lec t ion data and ver i f ied by Deep Test Hole No. 2; and the desp 200 foo t weathered sand interpreted on Line 4 re f rac t ion data, ve r i f i ed by Test Hole No. 4 are examples of the abil i ty of the program t o achieve, to some extent, t h i s more demanding objective.

The poss ib i l i t i e s of detai led gravity work have been investigated. Gravity work would not help i n determining val ley f i l l 1l.thology and would not help i n making depth determinations where the bedrock pro- f i l e i s r e l a t ive ly smooth, but ridges, terraces and channels would be observable and would permit a depth to-bedrock calculation where they occurred. Thus gravity may detect the bedrock terrace indicated by

0

?

e

40 seismic underlying the west half of Line 4. l e m on the northwest end of Line 2 where t h e "bedrock" encountered i n Test Hole No. 3 may be a d e t r i t a l s t r inger , thick d e t r i t a l lense or a bedrock terraco. The bedrock highs underlying Lines 2 arid 5 would be discernable even without the proximity of la rge outcrops.

It would resolve the prob-

Note t h a t the t o t a l cos t of l a s t year's seismic program was about $1,600 per mile. $1 00 per mile.

Regarding the seismic operations, I would i n fu ture recommend an increased e f f o r t t o obtain re f lec t ion data by shooting addi t ional holes. It appears the s l i g h t extra expense would y i e ld a rewarding amount of data. factory record qua l i t y can be anticipated.

The cost of a small gravi ty survey would not exceed

This should of course only be attempted i n areas where satis-

If it is necessary t o define the valley li thology and configuration i n more d e k i l , I think seismic has a ro l e to play. ed from each test hole can be extrapolated over a la rger area more economically than by dr i l l i ng . some spec i f ic problems of bedrock configuration. seismic and geological data there is a good chance tha t meaningful grav i ty r e s u l t s can be obtained.

The knowledge obtain-

It i s possible that graeity will solve Incorporated with

. .

SEISMIC LINE ’I LEGEND

FIGURE 3 LOCATION OF SEISMIC LINES

NORTH END OKANAGAN RIVER BASIN

LEGEND SEISMIC LINE + I 6

WELL LOCATION

CONTRACT NUMBER

TEST HOLE NUMBER

0

c TH

SCALE I : 50,000 -.

FIGURE 4

LOCATION OF SEISMIC LINES,

SOUTH END OF

OKANAGAN RIVER BASIN

APPi:IK)DIL B - COMPCSITE TEST HOLE LOG3 - CONTRACTS 42 b 41

Eleva t ion ( n o ) + 1715 f e a t Locstlon: ,,EO; f o e t south of L n t 50°26s15" N and ;,500

f e e t ens t of Long 119°15t00" W.

Depth

0 - 160 s i l t 160 - 200 send 200 - 810 s m d ; some s i l t 810 - 1140 s i l t ; some .end

j i n f e e t 1 &!e,

1 l h O - 1290 sand and n ~ s v e l . some s l l t whi te - - snd grsy

1290 - 1510 s i l t , aand; some clny, gray 1510 - 1650 clay, s i l t , snnd, blue-grny 1650 - 1740 clay. grsy-blun 17140 - l R 3 0 send lA30 - 1884 t i l l ; clsy, s i l t , snnd, grnvel 1884 - 1892 bedrock

Elevat ion lmmpl. l l6O f e e t Location: 12,660 fa 'e t no r th of Lat 50°26*15" N and 1.300

f e e t west of Long 119°07930" 'W.

Depth ( i n f e e t )

1000 - lllr0

h s i l t , grey ssnd, gray s i l t , g r a y s i l t ; some sand; some sand end g rave l 940 - 960 l e e t sand end Emve l t i l l , gray and whits s i l t , sRnd and g r a v e l S i l t . g'ny s m d and s i l t , gray nnd white till bodrock

Elevet ion (ma I 12 l> t e a t Location: 2 , l O b f e e t no r th of L 8 t 50°30'00" X and 600

l e e t weat of Long 119 07'30" K.

Depth ( i n f e e t 1 * *

0 - 230 230 - 500 500 - 520 520 - 700

940 - 1040 1040 - 10!+6

Silt, gray s i l t ; some sand. grng sand s i l t , RmY s i l t , sand, pebbles '

till

sand and g rave l ; aome s i l t bedrock

s i l t , gray

%cE4

Elevat ion (map): 1 300 f e e t Location: 10,600 f t e t south of Lat 4 9 9 2 ' $0'' N and 8,900

f e e t west of Long 119°30t00" W.

Depth l i n f e e t 1

0 - 190 190 - 290 290 - 510 510 : 580 580 - 670

670 - 710 710 - 760 760 - 770 770 - 800 800 - 822 822 - 848

a 3

grave l and boulders sand nnd g rave l ; occssionnl s i l t y send g rave l and sand sand and gravel grave l snd sand severe l o a t c l r c u - l a t i o n problem irom 578 t o 590 f e e t sand and g rave l r r a v e l and send sand and g rave l g rave l end t i l l gravel . 1o.s: c i r c u l n t i o n 800 - 818 f e e t bedrock

Elevat ion (map): 1325 rest Location: 6.000 f e e t south of Lat 50°26'15" N end l4.000

f e e t wost of lone 119°07'30" w Dnpth

( i n f e e t )

0 - 20

40 - 60 20 - 40

60 - 85

95 - 120 85 - 951

&e c lay , pale brown s i l t . c l ay , pa l e yel lowish brown a l l t . p e l s ye l lov iah brown and l i g h t grsg. oxidized t o 50 f e e t s i l t , g rave l , l i g h t olive grny and yellowish grny gravel bedrock

E leva t ion (map). 1265 l e n t Location: 4,200 f e e t sou th of Lat 50°26'15" N and 7,800

f e e t tieat of Long 119°15*00" W.

Depth

0 - 90 c l ay , oxidized t o 50 f t . pa l s

j i n f e e t 1 &K

ycl lowlsh brown, l i g h t gray and l i g h t o l l v e g ray

90 - 180 s i l t , l i g h t o l i v e gray 180 - 190 clny. l i g h t o l i v e gray 190 - 200 s i l t , l i g h t o l ive gray 200 - 220 c h y , l i g h t olive gray 220.- 310 sand, f i n e t o medium g re insd 310 - 350 sand, v e r y fine grained 350 - 400 ssnd. f i n e t o medium g ra ined 400 - 410 si l t , light olive grny 410 - 430 eand, f i n e grained 430 - 500 ' s i l t . l i g h t o l i v e gray 500 - 540 sand, f i n e t o medium g r s ined 540 - 590 s m d , very f i n s g ra ined ; some silt

l i g h t o l i v e gray

Elevat ion (map). 1270 f e e t l oca t ion : 6.300 f e e t sou th of Let 50°30'00" N and 3,800

l e a t west of Long 119°07'30" W.

0 - 20 cley. light brownish gray 20 - 40 clay; soma s i l t , l i g h t o l i v e gray 40 - 110 a l l t , oxidiand t o 50 f e a t . l i g h t o l i v e

gray. l i @ t gray and yel lowish grny 110 - 150 sand, l i n e g r s ined 150 - 160 ' s l l t , yel lowish grey 160 - 200 sand. V e r v f i n e Rralnsd: same s i l t .

yel lowish-gray - M O - 245 t i l l - aend , g rave l and s i l t , oxidized,

Dale j e l l o u i s h brown and very p a l s

245 - 295 295 - 320 320 - 330 330 - 415

415 - 450

. - . . orange sand. g rave l and s i l t , yel lowish grey till, yel lowish gray nebbles . sand. m e r e 1 and clav t i l l - c l a y , S I i t r sand end g rake l ; some grave l . oxidized 370-400 f t , pa l e yel lowish brown bedrock

Elevat ion (map): 1570 f e e t Locstion: 11.2Ocl f e e t South of Lat 50°26'15" N and 13.300

f e e t o a s t of Long 119°22'30" W.

Depth ( i n f e e t )

0 - 10 10 - 50

50 - 70 70 - 140

140 - 170

170 - 200 200 - 230 230 - 290

290 - 350

350 - 390 390 - 470

470 - 510 510 - 548 548 - 576

a grave l sand, medium t o CosrSe grained. some . grave l , p a l e ye l lowish brown s i l t , sand, very f i n e grained, aome coarse sand. l i g h t brown sand, l i n e t o medium g ra ined ; p s l e ye l lowish brown sand, medium t o conrso grained, yel lowish gray sand, f i n e t o conrs- grn lnsd , oxidized t o 200 f t , g ray i sh orange pink sand. d r y f i n e grained, light gray aand, f i n e t o medium grained. p ink i sh g r a y aend, coarae grained t o f i n e gravel, l i g h t o l i v e g r a y grave l sand. E O ~ I S ~ and very coa r se grained,

send, medium t o coa r se grained g rave l . some sand bedrock

loma grave l

Elevat ion (mnpl: 1.180 r e a t Locntion: 8.100 f e e t south o r Let 50°33'45" N and 1,500

f r e t e a s t of Long 119°07'30" W.

Depth l i n h t l

0 - 2 0 20 - 50

50 - 370

370 - 400

400 - 430

430 - 450

450 - 550 550 - 640

640 - 690

690 - 790

790 - 860

860 - 875 875 - 912

h clay, oxidized. pa l e brown s i l t , Some clay, oxidized t o 50

silt, l i g h t grny, l i g h t ollrs gray and yel lowish g ~ a y sand, very f l n n g ra ined ; some s i l t . l i g h t olios gray

l i g h t o l i v e grey aend. VOFJ f i n e grained, l l g h t olive

s i l t . l i g h t olivs grey aand. f i n e and Qary f i n e grs lnad. l i g h t o l i v e gray sand, f l n a nnd very l i n e grelned; some s i l t , light o l i v e gray till , s i l t . sand f i n e t o very coarse gralnad snnd, and f i n e g r ~ ~ e 1 ; Some oxidized Zone)B, l i g h t olive grny aand, medium t o vary eoorra grained, l i g h t o l i v e g r a y , grny l sh orsnge pink mnnd. g r o v e l . s i l t y . l i g h t o l i v e grny bedrock

r e s t , l i g h t o l i v e gray

' aand. f i n e and vary f i n e greIned,

grey

a 42

P

HYDR0IGM)ILX;Y OF VASEUX CREM AND

VERNON CREEK SUB-EASINS

BRITISH COLUMBIA

bY

E. C. Halstead

HYDROGlDI&CY OF VASEUX CREEK AID

VERNOII CREEK SUB-BASINS

BRITISH COI,UE.IBIA

by E. C . Halstead

Hydro lo g i c S c i en c e s D i v i s i on Inland Waters Branch

The purpose of the Canada-British Columbia Okanagan Basin Agreement i s t o develop a comprehensive framework plan f o r the development and management of water resources fo r the soc ia l betterment and economic growth i n the Okanagan Basin. s tud ies be broad i n scope so a s t o examine possible a l te rna t ives f o r t he e f f i c i e n t u t i l i z a t i o n and provision of an adequate quantity and qua l i ty of water i n the basin and i n those areas l i k e l y t o be affected by diversion. quant i ty s tudies as required t o evaluate the ex is t ing hydrologic regime i n the basin, including s tudies of run-off, lake leve ls , flows, groundwater and geological s t ruc ture ; climatology and meterology; t o evaluate means of regulat ing flows through storage diversion; and t o evaluate means of augmenting'water supplies w i t h i n the Okanagan Basin.

The terms of reference suggest that the

The hydrology task force i s responsible f o r water

Changes i n a hydrologic regime are due t o snowmelt, precipi ta t ion, evaporation and groundwater discharge and recharge. are underway, t he purpose of which, i s to examine and evaluate each of these parameters. of groundwater i n sub-basins. drainage basin provides the headwaters f o r some 35 t r i bu ta ry drainage basins of which 6 have been chosen f o r inclusion i n t h i s study. 6 are, on the e a s t s ide l i s t i n g from south t o north, Vaseux Creek, Pentlcton Creek, Pearson Creek and Vernon Creek; on the west s ide Lambly Creek and Greata Creek (a t r ibu ta ry of Peachland Creek). ob jec t of the reconnaissance invest igat ion was to determine whether o r not the groundwater component of the sub-basin i s i n su f f i c i en t volume to warrant the expenditure of more time and funds t o prolride as complete as possible an assessmant of i t s contribution t o the hydrologic regime. Preliminary investigations were carr ied out i n each basin i n September 1970 and the r e s u l t s together with any avai lable hydrologic data a re presented on the accompanying hydrogeological maps and br ie f notes. Existing data was not consistent, and as mapping was l imited t o logging roads, the presentation on each map differs but nevertheless the maps r e f l e c t an environmental pat tern and serve a useful purpose t o inform and support fur ther planning..

Investigations

This repor t deals with the preliminary' invest igat ion The upland area rimming the Okanagan

The

The

44

VASEUX CREEK

Vaseux Creek (Fig. 1 ) includes a drainage area of some 97 square miles above a gauging s t a t i o n s i tua t ed a t a poin t about 5 miles upstream from the mouth of the creek where it joins Okanagan River. Creek drainage basin rises t o elevations of more than 6,SW feet and more than 75 square miles lies above an el-evation of 4,SOO feet . Vaseux Creek is the trunk stream f o r 5 major t r i bu ta r i e s .

Vasew

Vasew Creek drainage basin is underlain by the Shuswap terrane t h a t comprises a group of metamorphic rocks but younger in t rus ive g ran i t i c and granodiorite rocks are e-xposed a t the surface over much of the area. the bedrock, i n par t icu lar the g ran i t i c rocks provided material f o r the deposition of grey s i l t y stony clay and till and meltwaters l e f t ice- contact and outwash gravel and sand t o form extensive areas of sur- f i c i a l deposits within the plateau-like uplands between elevations of 4,000 and 5,000 f e e t (see map, d i s t r ibu t ion of surf ic i .a l deposits) . These s u r f i c i a l deposits not only provide a s o i l (Fig. 2) f o r the s tands of timber covering t h e area but also provide a medium f o r the s torage and movement of groundwater contributed by snowmelt seepage.

During Pleistocene t i m e the area was i ce covered and erosion of

HYDROMGY

No climatological s+tations o r snow courses exist, i n the basin. gauging s t a t ion on Vaseux Creek, a t an elevation of about 1,,500 f e e t , has been i n operation since 1958 providing continuous records (Fig.3). A bar graph chart shows the runoff (see map) f o r the 1966 water year and i t s monthly d is t r ibu t ion . b u t the graph i l l u s t r a t e s the d is t r ibu t ion of the dischwge which reaches a peak i n Nay following t h e near disappearance of the season's snowmelt.

A

The 1966 water year was below normal

The s t u Q of groundwater florq systems i n c rys ta l l ine rocks un& pr a s imilar geological environment was undertaken by D . W . L;wsonScin the

-I$ Lawson, D. W. , Groundwater flow systi?ms i n the c rys t a l l i ne rocks of

t he Okanagan Highland, Br i t i sh Columbia. Journal of Earth Sciences, Volume 5 , 1958.

Canadian

Figure No. 2 - Vaseux Creek drainage basin, unconsolidated surf i c i a l deposits w i t h stand of lodgepole pine.

P F i w e No. 3 - Hydrometric Station, Vaseux Creek.

,d .. I

Trapping Creek drainage basin tribiitqry t o the West Kettle River and about 20 miles northeast of Vase- Creek basin. n e t f o r that basin depicts l o c a l flow systems superimposed on an intermediate flow system t h a t i n t u r n overl ies a regional flow system. Lawsm concluded that flow through the combined regional and in te r - mediate flow systems is a t most l e s s than 2 percent of the flow through the loca l flow system and the loca l flow system adjacent to the creek supports the groundwater component of baseflow. l o c a l flow systems i n t he c rys ta l l ine rock conplex contributes f ron 10 t o 17 imperial gallons a day per foo t thickness of aquifer. In the Vaseux Creek basin a l oca l flow system ex i s t s i n the permeable s u r f i c i a l deposits and the intermediate and regional flow systems a re confined t o the massive bedrock i n which flow is negligible and hence these systems can be discounted as providing any s igni f iccmt volume of water t o the overal l regime. The loca l flow systems during the 1967 water year contributed a baseflow i n the order of 3 c f s dwing the months of August and September and it i s assumed t h a t discharge during those months was en t i r e ly groundwater. rate during the year provided a l i t t l e more than 10.5 percent of the t o t a l discharge of 43,110 acre feet .

The quant i ta t ive flow

I n Trapping Creek the

Groundwater discharge a t this

Water samples were collected from 7 points i n the basin t o assess by geochemical means any groundwater contributions t o the creek discharge. The chemical analyses are presented i n Table I and bar diagrams on the accompanying map show the t o t a l of dissolved so l id s a.t sampling points. centrat ion of t o t a l dissolved so l ids and this represents groundwater discharge t h a t had been s tored i n the unconsolidated depolsits primarily of a g ran i t i c provenance hence the higher concentration of t he cations calcium, magnesium, sodium and potassium. The samples collected on '

Vaseux Creek below the entrance of McIntyre Creek have a l e s se r concentration of cations because the discharge from this creek is in p a r t snowmelt and surface runoff from Baldy Mountain which r i s e s to an elevat ion of more than 6,500 f e e t a t the drainage divide. The sample, taken a t the gauging s t a t i o n where discharge a t the time of sampling was i n the order of 3.0 cfs shows the r e s u l t of mixing of Fish Creek and McIntyre Creek discharge and compared with t h e analyses of the sample collected near the creek mouth there i s no rea l change indicat- ing 110 groundwater contribution i n the canyon below the gauging s ta t ion .

Discharge from the Fish Creek t r ibu tary has the highest con-

CONCLUSION

A regional pa t te rn shows up i n t h i s watershed and s imilar ly snow accumulation and snowmelt above elevations of 4,000 f e e t a r e the major sources of runoff and annual groundwater recharge and discharge. though the groundwater component i s s ign i f i can t and provides f o r a base flow of a t least 3.0 cfs da i ly during the l a t e summer months i t i s

Al-

recommended t h a t the above assessment i s va l id f d r present planning.

t o give prec ip i ta t ion and snow accumulation data and i f funds a re ava i lab le it i s recommended t h a t an observation well i s in s t a l l ed near a snow course and f luctuat ions of the water tab le observed i n that wel l can be correlated with the snow course data t o provide accurate forecasting. A . Pipes, U. B. C. C i v i l Engineering Division is present- l y preparing a paper t o provide r e su l t s of his research i n Carr's Landing IHD basin regarding groundwater leve ls and snowmelt recharge.

(. Climatological s t a t ions should be established i n the drainage basins

P

I e

f;t PI

rl d C

r;l c

ri TI c

rl .rl C

rl .rl c

d 'E!

rl .rl c

rl .rl c

h t' .d C

cv 0 - cut-m+rT . . . . . o\ \n 0 cu th In m c- 0 m t h o c u cu

47

48

m o w CREEK

\ -

Vernon Creek drainage basin (Fig. 4) occupies an area of about 52 square miles of which more than 35 square miles are above an elevation of 4,000 f e e t . an elevation of mre than 5,400 fee t . Lake basins cover more than 1.66 square miles of the upland area and provide basin storage f o r snowmelt runoff. Creek to empty into Ellison Lake some 8 miles d i s t an t a t an elevation of approximately 1,400 f ee t . One t r ibutary, Clark Creek, drains an a rea below the 4,250 f t . contour and discharges i n t o Vernon Creek a t an e levauon of about 1,500 fee t .

Long Mountain, the highest point i n the basin reaches

Discharge from the lakes system flows through Vernon

The basin is underlain by metamorphic rocks of the Shuswap terrane that commnly occupies much of the eastern upland area adjacent t o the Okanagan drainage system. occupying an area west of Swalwell Lake including W r M y Face C l i f f a r e some shales and lavas that a t most are not mope than 500 f e e t thick Tha lavas flowed out over an erosional surface on the Shuswap terrane during the Tert iary period and it i s inferred t h a t the lake depressions could be remnants of this erosional Surface. covered the area and with the disappearance of the i c e the upland area was covered with a th in mantle of silt and silty till whereas below 3,000 f e e t the bedrock is covered in general with norainal deposita washed and channelled by meltwater overlain a t l o m r elevations by poorly sorted gravel, sand, 3i1t and clay t h a t form the de l t a of the present Vernon Creek.

Overlying these metamorphic rocks and

Thereafter g l ac i a l i c e

The mantle of s i l t y sandy clay and till supports a cover of immature timber above an e l e m e o n of 3,500 f a e t (fig. 5) .

Climatological s ta t ions have not been established i n the drainage basin but beyond its eastern linit and a t an elevation of b,300 f e a t a snow course has been in operation for more than 30 years. The wates equiva- l e n t on April 1 s t a t this point I s commonly i n the order of 5 inch3s. The volune of ~zeltwater from th i s snowpack is tho recharge fo r basin storage i n the lakes, soil moisture and groundwater storage i n the underlying s o i l s and rocks and provides fo r runoff t h a t typical ly reaches a peak i n May. cate the 3 year average storage from the snowmelt i n the Vernon

Records f o r the years 1966, 1967 and 1968 indi-

49 watershed amounted t o 8,057 acre f e e t f o r Swalwe3-1 Lake'(Fig. 6) and 2,226 acre f e e t - f o r Crooked Lake. is controlled by dams a t the west end of both lakes (Figs. 7 and 8) and therefore flow through Vernon Creek is regulated. recharge and discharge within the basin supports the vegetative cover but i t s contribution t o base flow of Vernon Creek is not considered su f f i c i en t to warrant fur ther investigation. Discharge of groundwater was noted i n September a t a spring l i n e a t an elevation of about 2,700 feet a t the contact of permeable silts overlying a till sect ion a t least 200 feet thick. than 3 gallons a minute and supported a growth of cedars and aspens. Below the spring l i n e groundwater continued to seep through a f rac ture i n the till and a t the cutbank on Vernon Creek amounted It0 an immeasur- able volume (Fig. 9 ) . Clark Creek was dry below about 2,750 f e e t e le- vation but discharge above t h a t point was su f f i c i en t to supply water t o a logging operator and the volume was i n the order of less than 0.2 cfs.

(0 The discharge of t h i s lake storage

Groundwater

Collective discharge of these sprfings,was l e s s

A sample of water was collected a t a point a t an elevation about 2,250 f e e t and below present construction f o r a storage dam (F:tg. 1G). qual i ty of the water, Table 1 , r e f l ec t s t h a t of surface water i n storage i n the lakes and hence confirms the inference thi3.t groundwater discharge is mi-1.

The

The regional pa t te rn a l so shows up i n th i s watershed where a t eleva- t ions of more than 4,000 f e e t snow accumulates and i ts meltwaters con- t r i b u t e to the storage of surface water and runoff providing the typ ica l annual discharge pat tern. Following the peak discharge, f lov through Vernon Creek is controlled. a r e not recommended f o r the Vernon Creek drainage basin.

Further groundwater investigations

..

7.- c

0 c,

Figure No. 5; - Vernon Creek drainage basin, unconsolidated sur f i c ia l deposits with stand of immature timber.

. Figure No. 6 - Swalwell Lake, September 1!?70.

Figure No. 7 - Earth dam, west end of Crooked Lake with discharge outlet .

Figure No. 8 - Hydrometric Station, 600 ft. down- stream from ou t l e t of Swalwell Lake.

r - . ... _.

P

Figure No. 9 - Groundwater discharge through fractured till, road cut to Figure No. 10.

Figure No. 10 - Storage dam under construction on Vernon Creek, September 1970.

- , . . . .. . . .

.. . . . .. . .. ._..__. _ _ .. .~ .. ._ _ L ._ . __. ... , . . .. .~ -

A HYDROGEOLOGICAL RECONYAISSLYCE STUDY

PENTICTON CWEX DRAINAGE BASIN

by P. L. Hall

A HYDROGEOIDGICAL RECONNAISSANCE STUDY OF THE

PENTICTON C R E E DRAINAGE BASIN by P. L. Hall

SUMMARY

The fo l lowhg points are made i n the repor t and are baaed on ex is t ing data, which is somewhat l imited, and may be modified when more data i s available.

For Penticton Creek

1 .

2. 3. 4.

5.

6 .

Area some 62.7 square miles. Elevation 11 00' to 7000'. M e a n annual prec ip i ta t ion var ies from approximately 1.5" t o 35". Approximately 100,000 acre feet of prec ip i ta t ion f a l l s on the basin of which nearly:

90$ occurs - above 4,000 f t . 80% occurs 7 above 4,f;OO ft. 70% occurs - above 5,000 f t .

and some 55% f a l l s i n the October - March period. Water Balance : Approximately 40% of prec ip i ta t ion goes to surface runoff. Approximately 60% is l o s t as evapotranspiration. Actual groundwater outflow is probably only 1 or 2% of t o t a l input, (1 to 5 c f s ) while baseflow is probably i n the order of 5 - 15% of surface runoff. A theore t ica l model could be developed to simulate groundwater movement wi th in this basin.

Three groundwater zones a re postulated:

(a)

(b)

( c )

i

Sur f i c i a l zone of l oca l flows, this zone i s ofton dry i n the summer. There is an intermediate ( 1 ) zone i n the lower p a r t of the Pleistocene and upper p a r t of f ractured bedrock. probably moves i n this zone. An intermediate zone ( 2 ) down to depths of 2200 -. 300 f e e t with flow becoming negligible (1s us gpd/ft ) a t depth.

Most water

\

(d)

Instrumentation could be installed t o monitor groundwater movement a t a cost of $5,OOO - $1 0,000 per piezometer nest and probably $50,000 would be needed t o i n s t a l l a groundwater network. The e f f e c t of groundwater movement on the shape of t h e discharge bydrograph could be determined f r o m hydrograph records o r perhaps by i n s t a lUng more weirs. I n view of the f a c t that say a 5% error i n precipi ta t ion measurement would probably r e s u l t i n the same quantitative error as a 500% error i n groundwater measurement, it i s thought bes t not to proceed with groundwater instrumentation unless a very detai led s t u d y i s made of one basin.

runoff during the snowmelt period. These wells should be care- f u l l y s i t e d i n a closed flow system, o r one with a l imited subsurface inflow/outflow, possibly in s u r f i c i a l materials on the plateau area. in s t a l l a t ion of the observation well. The well shou:Ld be care- fully designed and instrumented.

There is probably very l i t t l e groundwater movement between drainage basins.

7.

8.

9 .

10. High l e v e l observation wolls may give some indication of surface

Careful mapping of such a s i t e should preceed t h e

53

Penticton Creek drainage basin i s located on the e a s t sidle of t h e main Okanagan Valley near the City of Penticton. The drainage basin covers some 67 square miles andoextends from l a t i t ude 49O30' to ,49040' and longitude 119O35' to 119 20'. The elevation ranges from approx-tely 1,100' a t the City of Penticton to some 7,000' a t Greyback Mountain.

MORPH0IIX;Y

Geology

The bedrock is comprised of gneisses and sch i s t s of the Shuswap Complex and is associated with the la te Mesozoic Okanagan intrusives . The bedrock is exposed i n numerous places and is covered by a th in veneer of Glacial deposits, mainly till and ice-contact material.

It appears t h a t Penticton Creek is s t ruc tu ra l ly controlled, as can be seen on the photo mosaic, there is a NNE-SSW l ineat ion, which is approximately p a r a l l e l t o Penticton Creek. There are seven tributary creeks to the main creek, a l l are a t r i g h t angles t o the NNE-SSW trend, the t r i bu ta r i e s to the t r ibu tary creeks are again a t r i g h t angles, i.0. p a r a l l e l to the NNE-SSW trend. are on the east s ide of the basin.

Elevation

The following table shows the areas between d i f fe ren t contours:

O f the seven t r ibu tary creeks, five

Area In % of

> 2500 4.1 5 6.10

Contour In t e rva l Square Milt Total Area

2500 - 3000 2.05 3.05 3000 - 3500 2.36 3.51 3500 - 4000 3.10 4.62 over 4000 - 4500

5-50 13.2) 8.20 over srft) LOO0 f t

5500 - 6000 16.29 24.25 61.17% 74.42% 82.62% 6000 - 6500 7.67 11 .LO

h5W - 5000 8.90 5Ooo - 5500 16.52 2 4 . 6 ~ 5000 f t

> 6500 0.65 0.97

67.19 1 oO.03

HYDROLOGY

Precipi ta t ion

Records are available from Penticton fo r the period 1907 - 1953, l a t e r records are probably available but the following averages are based on these figures:

i.

Mean Annual Precipi ta t ion 11.31 11

Minirmun 1928 - 1929 5.73" 1948 - 1949 18 .47"

Monthlg Averages :

OCT. NOVO DE. JAN. FEB. APR. MAY JUNE JULY AUG. SEPT. -~ ~ ~ ~

precip.in..o.94 0.94 1.12 1.03 0.80 0.67 0.77 1.10 1.33 0.86 0.86 0.89 $ of total 8.31 8.31 9.9 9.12 7.07 5.92 6.81 9.7311.76 7.60 7.60 7.87

The Hydrology Division of the Mater Investigations Branch has developed the following multiple regression equations t o calculate prec ip i ta t ion i n the Okanagan from elevation, l a t i t ude and longitude.

The equations are given below:

= 0.46 X., 4 b.29 X2 = 206.3 0 0.267 X, + 2.574 X2 .. 124.49

P3 0.238 X, + 2.098 X2 - 101.61

p1 y2

Where IC, = elevation i n hundreds of f e e t Latitude 0.6. L9°20'

and Y1 - Mean annual precipi ta t ion i n inches *2

Y2 = Oct. March mean precipi ta t ion i n inches

Y3 = Nov. March mean precipi ta t ion i n inches

Penticton Creek extends from l a t i t ude 49'30' t o f~9~40' which gives an approximate increase of half an inch of mean annual precipi ta t ion i n the north of the basin.

Limitation of the Equations

The equations are based on data f r o m below 4,000' and so are not

i 55

ver i f ied above th i s .

The confidence limits of the values are not calculated here, as the main purpose of using them is t o show the a rea l d i s t r ibu t ion of pre- c ip i t a t ion over the basin. meteorology are being carried out by other task forces.

More detai led s tudies of the hydrology and

Mean Annual Precipitation

Area Mean Precip. Contour Mean i n sq. Annual acre

In te rva l Elev. miles i n i n . f e e t

2500 2100 4.15 14.86 3,288 2500 - 3000 2750 2.05 17.85 1,951 3000 - 3500 3250 2.36 20.15 2,535 3500 - LOO0 3750 3.10 22.h5 3,711

The t ab le shows t h a t less than 5% of the precipi ta t ion f a l l s below 3000' mainly due to the small area below 3000' (10% of total area). Yet 88% of the precipi ta t ion is derivsd from 4000' and higher, 81% from 4500' and higher and 68$ from 5000' aad higher, Fig. 1.

Y2 October - March Precipitation

Mean elevation Oct-March Precip . Cumulative Total between controus inches. acre-f oe t

8.02 9.75 11.09 12.42 13.76 15.09 16.43

19.10 '

20.30

17.76

1,774 1,066 1,395 2 , 053 4,035 7,163 14,471 15,430 7,811

703

55,901 54,127

55, PO1

\

c.

i

56 As can be seen, j u s t over half of the mean annual. precipi ta t ion falls from October to March. GT t h e October - March precipi ta t ion occurs as snow and remains on the ground u n t i l the spring t h a w .

It should be borne i n mind t h a t a large p a r t

Surface Runoff

A P.F.R.A. Report of 1963 (Ref. No. 5 ) indicates that the, 25 year average runoff (pr ior to 1963) is some 43,000 f t . o r approxim.ately equiva- l e n t t o 12" over the whole basin (Fig. 2)

If the total precipi ta t ion over the basin i s i n the region of 100,000 acre-feet, as calculated from the regression equation, then approximately half of the precipi ta t ion i s l o s t i n evaporation, it will be shown that groundwater outflow from the basin is negligible. course, both the estimates of runoff and precipi ta t ion a m subject t o considerable e r ror , but w i l l be refined a s the study continues.

Of

Gno of the problems on Penticton Creek is the number of man-made storage schemes.

The Upper Penticton Creek storage reservoir consists of bwo dams, #1 dam capable of s tor ing 1,200 acre-feet and #2 dam stor ing 10,240 acre- fee t . The catchment area is approximately 12.3 square miles and the estimated average runoff ( R a f . No. 5 ) is 8,900 acre-feet or 13.6". minimum esti~nated runoff is 2,000 acre-feet o r 3.1".

The average runoff of 13.6" appears low i f the estimate of prec ip i ta t - ion of 30" o r so, f o r 5000' and higher, i s correct. th icker Pleistocene cover over t h i s area and i t could be that the groundwater runoff from th i s area is much higher than the r e s t of the basin.

The

There is a much

I n addition t o the Upper Penticton Creek reservoir, there is 100 acre- f e e t of storage on Howard Lake and 150 acre-feet on Corporation Creek.

It i s thus quite d i f f i c u l t to estimate the na tura l flow. are being in s t a l l ed on tho Upper roservoir, t o determine reservoir storage, below the upper dams to determine flow released from them and j u s t above the dam a t Campbell Mountain, to measure the flow going in to the lower storage area and diversion tunnel..

Stream gauges

The spring snowmelt generally begins i n April and proceeds upwards a t an approximate r a t e of 500' per week u n t i l the snow melts on the 7000' peaks i n late June.

The peak runoff generally occurs i n l a t e May and is i n the order of 200-300 cfs . August and September is 20 acre-feet per day o r 10 c f s with flows as

According to reference No. 5, the natural flow i n July,

57 low as 5 acre-feet per day (2.5 c fs ) . If we take the low flows as being mainly groundwater discharge, then say groundwater discharge i s 7 cfs or approximately 5000 acre-feet per year and assuming the value of k3,OOO acre-feet is correct f o r average na tura l discharge, then the groundwater component of the discharge (baseflow) is i n the order of 11 .%.

Groundwater Flow

As has already been mentioned, the groundwater component of the hydrograph is possibly i n the 5% - 15% range of t o t a l flow. I n addition to this, there w i l l be a cer ta in amount of groundwater flow out of the basin. There a re thus two fac tors t o consider:

1 . The e f f e c t of groundwater flow within the basin, tu13 w i l l gener- a l l y a f f e c t the shape of the discharge hydrograph and be a major influence on low flows.

2. The 'amount of water actual ly leaving the basin aa groundwater flow.

Amount of Groundwater Leaving the Basin

As the Pleistocene deposita are only a th in veneer over ,the bedrock, w e will consider the b d r a u l i c properties of the bedrock.

The bedrock i s generally highly metamorphosed (gneiss, granodiorite) and so the hydraulic conductivity w i l l be dependent on s t ructure i.e. jo in ts , fissures and sheer zones. There appears to be a pronounced . j o i n t system running approximately p a r a l l e l to the main creek (NNE-SSW) and a t r i g h t angles to th i s ; both a re nearly ver t ica l . I n addition, there appears to be a smaller system associated u i t h a fo l ia t ion< s t ruc ture dipping generally to the Sd.

These jo in t s have been opened t o several centimeters by surface weathering and undoubted3y close up with depth. diversion tunnel a t Campbell Mountain indicated f ine f i ssures up to 140' below the surface with inflows of up to 1 g p m i n the test holes. No d e t a i l was given on the diameter of the hole o r depths a t which water came up (Ref. No. 6).

Test d r i l l i n g for the

It thus appears tha t the hydraulic conductivity, k, could probably be expressed as a function of depth and would probably be insignif icant below depths of say 500 - 1000'. water outflow from the basin, other than near the mouth of the creek and possibly minor amounts near the topographic divides.

So there would be very l i t t l e ground-

The P.F.R.A. d r i l l e d a t e s t hole i n the val ley bottom near the site of

58 the diversion tunnel and dam. T h i s test hole i n e c a t e d there was some 70 f e e t of overburden above bedrock, although it may be that the hole was terminated i n a large g ran i t i c boulder.

Field permeability tests gave values i n the range20f 0.06 to 0.3 f t / min. ,++which is approximately 5.5 x 102 us gpd/f t. f t .2 .

t o 2 . t3 x 103 us gpd/

The authors of t he repor t assume a hydraulic head d i f f e r e n t i a l of 25' a t the dam, a flow path of 250 feet and a cross-sectional area of 13,000 square feet.

From t h i s , they derive an underflow of from 2-10 c f s .

Using D'Arcy's Law

2 Q = MA Where Q = flow i n us gpd K = hydraulic conductivity us gpd/ft. I =I hydraulic gradient A = Cross sec t iona l a rea

5 2 Q = 5.5 x IO2 x 25 x 13,000 = 7.1 x 10 US gpdlft. 250

6 2 Q = 2.8 x lo3 x 25 x 13,000 = 3.6 x 10 us gpdft . m 5 Dividing by 6.46 x 10 to obtain flow i n cfs , we have:

Q = 1.1 to 5.5 cfs.

To make a rough estimate of the natural flow through the channel above the dam, where the new weir w i l l be s i t ed , consider the following simplified cross section:

100' 200 ' 100'

I C [ A 40' I C 1 I I I I

B 30' J C

Where: A = coarse gravels and boulders B = f i n e sands C = f ractured bedrock

* 4 t o convert to us gpd/ft.2J multiply ft/min. by 1.075 it 1 o .

59 If we assign the following b d r a u l i c conductivit ies t o each unit:

Cross sect ional area A

= 8,OW f t 2 4 KA = 10 us gpd/ft2 AA

% = lo2 us gpd/ft2 = 6,000 f t 2 I

KC = 10' us gpd/ft2 AI: = 3b,OCK! f t 2

And assume a hydraulic gradient of approximately 150 f t h l i l e ( the same as the creek bed).

I We have: Q = K I A 4 6 QA e 10 x 150 x 8000 us gpd approx. 2.4 x 10 us gpd 'm- 2 4 QB = 10 x x 6000 us gpd approx. 1.8 x 10 us gpd

0 2 Q, = 10 x 150 x 34,000 us gpd approx. 1.0 x 10 us gpd * T O

I 6 Total approx. 2.4l&l x 10 o r approximately 3-11 cfa.

Groundwater Flow Within the Basin

A s has already been mentionod, the geology of the basin conprises of a t h in veneer of Pleistocene deposits over gneissic bedrock. The Pleis- tocene deposits vary from silts, sands and till t o gravels with extremely rapid l a t e r a l var ia t ions.

A theore t ica l groydwater flow pa t t e rn i s described below, this is , based on work by Toth (1962, 1963) and Freeze (1966, 67a,, 67b) suggests a system of three major f low components: ( I ) loca l , (2) i n t e r - mediate, ( 3 ) regional. rock with depth, it is suggested here that the regional flow between dralnage basins is negl ig ib le lor absent. there be two flow zones fo r Toth's l o c a l flow system, these a re designated KA and %, the term Kc is used f o r the intermediate flow path.

Toth

Due to the decreasing permeability of the bed-

It is fur ther proposed tha t

Local flow Zone KA

It i s proposed tha t tho upper p a r t Pleistocene cover be designated a loca l flow zone; i n places t h i s zone would extend dorm to bedrock, i n others, the lower p a r t of tho Pleistockne m a y be b e t t e r grouped with zone $. i s characterized by numerous small f low systems The zone K A

60 (see diagram ( 1 ) ) . phy and lithology, some character is t ic s i tuat ions causing springs a r e shown i n diagram ( 1 )

Local springs are caused by variations i n topogra-

During August 1970, f i e l d examination showed tha t most of the springs had ceased flowing o r were only discharging a t 5 - l C us gpm, this was due t o the low precipi ta t ion and high evapotranspiration. s i ze s the seasonal var ia t ions w i t h i n t h i s zone, much higher flows would be expected after the snowmelt period and a l so a f t e r heayy rains .

This empha-

T h i s zone would be an extension of zone KA, it i s shown i n diagram ( 2 ) . T h i s zone would comprise of the lower p a r t of the Pleistocene, the fractured tills and leached zones. It also includes the 'upper few f e e t of the bedrock where the jo in t s are opened by weathering, this zone would extend 5-1 0 o r 20 f e e t below the bedrock surface. conductivity of t h i s zone would be generally higher than tha t of the overlying zone and would probably be extremely variable, from say, 1 to 100 us gpm pel. f t 2 . T h i s zone w i l l i n general, be more uniform than zone K and w i l l show smaller water leve l f luctuations.

To measure the amount of water flowing through t h i s zone, we could use ' the following elementary formulae.

The hydraulic

k

!\ - Q = PIA Where P = Permeability .

I = Hydraulic gradient Q = VA A = Cross sect ion area

V = Velocity

The hydraulic gradient 'I' could be assumed to be nearly the same as the topographic gradient, pressure t e s t s would give permeability and also a possible depth a t which this zone could be terminated. tively velocity, V, could be obtained from inject ing t racers .

Alterna-

One feature of this zone is the major spring l i n e a t approximately 5000 ft. where there i s a d i s t i n c t break i n slope. t ion the topographic gradient i s approximately 500 ft /mile while below it is i n the order of 1000 ft/mile. conductivity, K, is such that it will support a hydraulic gradient of 500 ft/mile but not 1000 ft /mile, a l ternat ively there could be a change i n hydraulic conductivity a t the change of slope, f o r example, till could be plastered against the lower p a r t of the slope. groundwater movement probably occurs within this zone.

Above this eleva-

T h i s shows t h a t the hydraulic

Most of the

Intermediate flow Zone K

T h i s zone would be ent i re ly within bedrock and would begin a t some

SCHEMATIC FLOW DIAGRAMS I/!

ZONE KA Surf ic ia l deposits

silt lenses cause

6000' ZONE KB B a s e of sur f ica l deposits and u p p e r p a r t o f

E 0

0 > Q)

w

.- c

-

weathered b e d r o c k .

spring line at major change in slope

Gradien approx. lOOOft./I mi.

3000'

PENTICTON CREEK DRAINAGE B A S IN

I , :.,, I,' Rt. s. . . p n.t.s. .L ~ ---__

. , DIAGRAM 2

61 a rb i t r a ry depth a t which there is a spec i f ic decrease i n hydraulic conductivity. decreases with depth, a P.F.R.A. t e s t holepat the s i te of the diversion tunnel found a permeability of $ us gpd/ft a t a depth of 138' below surface. It is thus probable tha t flow becomes ins igni f icant beyond depths of say 200' and f o r mathematical simulation an impermeable boundary could be assigned t o varying depths, say 200-500 f t . It is thus evident t ha t there would be no s igni f icant flows between basins and the groundwater from this zone would discharge i n t o the valley bottom.

As has been s ta ted e a r l i e r , hydraulic conductivity, K, i

It is proposed t h a t no regional flow component be created, f o r the above reasons.

Mathematical models developed by Freeze (1966, 67a, by c y ) could be ut i l ized to a id i n the interpretat ion of the groundwater flaw system. This would involve assigning r e l a t ive values of K t o a multilayered aquifer system.

To check any theory i n the f i e l d would be expensive, Involving the in- s t a l l a t i o n of piczorreters. This is discussed under instrumentation.

Instrumentation

I n order t o measure groundwater f luctuat ion i n tho f i e l d , it would be necessary t o i n s t a l l piezometers, a minimum of throe nests i n any pro- file would be necessary to define the water-table plane (see diagram below)

? P L A N

I Piezometer nests

Creek

A t each nest , a t l e a s t one piezometer would have to be in s t a l l ed within each of the three proposed flow zones. gradients (I) and the r e l a t ive ly high ve loc i t ies associated with f i s - sure flow, i n conjunction with a low storage coeff ic ient (S) water- tab le f luctuat ions w i l l be both rapid and r e l a t ive ly large. Conse- quantly, the water l eve l should be monitored by recorders ra ther than manually

Due t o the s teep lqdraul ic

It would cost$S00 to $2,000 to d r i l l each hole, it may be that nests

62 of piezometers could be completed at d i f f e ren t depths within each hole or d i f f e ren t holes my have to be d r i l l e d f o r each depth, depending upon conditionsandhole diameter.

Recorders would cos t approfimately $500 f o r a s ingle channel, with multi channel recorders costing mre ( f o r d i f fe ren t piezometers) so cos ts would vary from say $3000 to $6000 per piezometer nest .

There would also be the cos t of access roads plo each site a t a cost of $2000 - $3000 per mile.

As s ta ted , a minitnun of three piezometer nests would be required to monitor one section. This, i n i t se l f , may not be representat ive of conditions a shor t distance away.

I n summary, it i s concluded t h a t it would not be just i f ia la le to install a piezometer network due to the high cap i t a l cos t and r e l a t ive ly small re turns

V" Notch Weirs

One a l te rna t ive is t o i n s t a l l small weirs a t numerous s t r a t e g i c points and anawe the hydrograph for the base flow component. these weira could also be used t o simulate surface water :runoff using flood routing tochniqiies .

Data from

The w e i r s are described by Hall and Langham (Ref . No. 9 ) and are con- s t ruc ted of 3/ht1 o r 1" plywood, reinforced wlth m e t a l angle i r o n and have a m e t a l l i p on the "Vfl notch to give a sharp cres t . The ra t ing curve of tho weir Kill depend upon t he angle of the notch, the caps; c i t y p n bs from approximately 7-12 c f s f o r a two-foot head on a 60 or 90 nV" notch; o'char ar.gZe3 could also be used. The weirs could be constiwcted f o r less than $250, an F-type recorder would c o s t approa- mately $450; with i n s t a l l a t i o n the weirs would cost approximately $1 000.

These weirs could be ins t a l l ed on the t r i bu ta ry creeks and a t d i f f e ren t elevations on one of the six basins under atudy.

In the I .H .D. study basin a t Carr's Landing, the Ifydrolagy divis ion has reported a good correlat ion between water-tabla f hct.uat;ions and snowmelt. m i o f f .

One possible explxIatlon is as fo l lows: e f fec t9 upon runoff from snowmelt, the a c t u l amount of water melting W i 1 - L go partly toward8 surface watss runoff phononlena and. par t ly as groundwater phenomena. This i n turn w i l l a f f e c t tho peak flow and its duration, Eghe r peaks and shortor duration high flows will be experi- enced when the surface vater runoff is more important.

Apart from the meteorologicdl

63 The percentage surface runoff to groundwater will depend upon the permeabili ty of the s o i l , among other factors . The permeability of the soil w i l l i n tu rn be affected by the amount and type of f r o s t i n the s o i l a t the time of snomnelt. s o i l moisture leve ls p r i o r to freezing and a lso upon depth and rate of freezing. The s o i l moisture leve ls will depend upon prec ip i ta t ion and evaporation p r io r to snowfall and the type of f r o s t w i l l dFpend upon freezing conditions p r i o r to snowfall and the insulat ing e f f ec t s of the snouf a l l . There may a l so be subs tan t ia l evaporation/condensation with- i n the s o i l moisture - snowpack system, depending upon va&our pressures.

( 0 The f r o s t s e a l w i l l depend p a r t l y upon

Thus monitoring the water-table may give a good index to be used i n estimating runoff from snowmelt.

If possible, small closed l o c a l flow syqtems should be instrumented with recording piezometers. If properly designed, the piezometers may also measure evapotranspiration i n the summer. a t d i f f e ren t depths i n the s o i l may also give useful indexes t o the f r o s t seal and would give information on i n f i l t r a t i o n rates during the spring, summer and f a l l .

Thermistcws i n s t a l l e d

Hydrochemis try

Seven saqles of wahr were collected from Penticton Creek arvl its t r ibu ta r i e s , these were znalysod by the Public Health Department. The locations where the samples were taken f rom ai- shown on Fig. 1 . aplalyaes are shown i n the accompanying table and on the Piper diagram.

The P As can be seen, the waters are r e l a t ive ly fresh, with If333 than 100 ppm dissolved solids.

The samples are generally calcium, magnesium, bicarbonate waters and there appears to bs 110 r e a l d i f f e rmce between the samples.

I n waters t h i s f resh, the anion/cation epm balance should generally be within s%, there i s up t o 10% difference i n sone analyses, which makes the a.?.rlalyses somewhat suspect.

The Water Ealance

If we consider the follcwing simple re lat ionship

(1) P = ET + R + As Where P = ET = R = *s =

From f igures available a t t h i s time:

Precipi ta t ion Evap t ranspirat ion Runoff, surfaco and subsurface Change i n storage, surface and subsurface.

,

DIAGRAM

c, 100

I

I00 80 so 20 0 0 20 50 80 100 -ca ++ C I - - C ATlONS ANIONS

PERCENT OF TOTAL EQUIVALENTS PER MILLION

Water Samples from Pent icton Creek

I

64 P approx. 100,000 acre-feet per year

approx . 43,000 acre-feet per year (surface) 3 approx. 1 - 3,000 acre-feet per year (groundwater) ~g approx. na tura l storage prob. small S

Potential. EX approx. 20" approx. 61,000 acre-feet.

Thus using equation (1 )

100,000 approx. 61,000 + 43,000 .+ 1 - 3,000 acre-feet

which near ly balances and considering the nature of the da ta , the balance i s qu i t e good.

It can be seen that the groundwater component is qu i t e small even when taMng baseflow as 5-15% of runoff (2,000 - 6,000 acre-feet) .

Errors within the Water-Balance

1. Prec ip i ta t ion

Errors i n catch by the rain gauge caused by locat ion of gauge, height above ground, type of gauge, wind speed, e tc . , w i l l add some s m a l l e r r o r say 2 5% f o r r a in a d possibly f o r snow, up to f SQg.

There is also the problem of extrapolating the gauge catch t o the rest of the basin.

Estimating the water equivalent of the snow cover over the basin can a l so lead to considerable e r rors .

@

2. Evapotranspiration

Losses from the snowpack by eva2oration and sublimation can be especi- a l ly high during t h e sno:melt period. As the snowmelt period extends over sevsra l weeks and rises i n a l t i t u d e with t i m e a r e l a t i v e l y sophis- t i ca t ed meteorological network would be necessary to estimate losses. Transpiration from the f o r e s t cover during s m e r will a lso be subject to considerable errors .

3. Runoff

Woirs generally have a-? e r r o r wargin of + S%, the error margin of the Penticton weirs w i l l be detarmined by o tzer t a s k forces.

4. Storage

If we assme t h a t each cf the Upper storage reservoirs ha.s a surface area of approxhate ly k square mile, or say, 150 acres, then a change

65 of 1/1OOth of a f o o t per day will give more than 1% acre-feet o r very near ly 1 cfs inflow or outflow. ure accurately small changes i n storage, especial ly i f one considers the f luctuat ions due to seiches and winds p i l i ng the waters up downwind.

Thus i t will not be possible to meas- 0

The possible e r ro r s i n the water-balance have been pointed out t o s h o w that many of these errors are of the same or greater magnitude as the groundwater outflow.

CONCLUSION

The main significance of groundwater i n this drainage basin i s i t s affect upon the discharge hydrograph. As t he groundwater zone is r e l a t i v e l y shallow and as gradients are high then there is probably not su f f i c i en t temporary groundwater storage to reduce peak flows s igni f icant ly , y e t there is su f f i c i en t storage to provide 5-20 cfs runoff during low flow.

66

WATER SAMPUS FROM PENTICTON CREEK

Sample No. 1 2

PPm epm %epm PPD ePm Pepm

I A C1- 0.80 0.023 6.50 0.30 0.009 1.39 N SO4-- 1.20 0.025 7.19 1.00 0.021 3.42

18.29 0.300 86.31 35.36 0.580 95.19 I * HCO

0 N Sum 20.29 0.347 100.00 36.66 0.608 100.00

S

C Ca++ 4.2 0.210 49.44 7.0 0.350 48.22

A Mg++ 1.1 0.090 21.34 2.8 0.230 31.79 T Na+ 2.2 0.096 29.22 2.8 0.122 19.99

I K+ 1.1 0.028 0.9 0.023

0

N Sum 8.60 0.423 100.00 13.50 0.724 100.00

3-

Total ppm 28.89 5’0.16

ePm ;6 Cations 1 f Anions 45

55 45.6 54.4

S.A.R. 0.25 0.22

PH 6.7 Conductivity as 42 micromhos/cm Total hardness

as Cam3 15.0 dissolved so l ids 28.9

7.2 68

29.0 50.4

Alkalinity++as CO n i l i n a l l samples. Flouri.de generally less than 3value obtained by multiplying CaCO by ‘I .219214. 0.1 ppm. alance should be wi th in : 3

- + 5% for total so l ids 100 ppm. - + 3% for total sol ids 100-250 ppm. - + 2% for total s o l i d s 250 ppm.

Sanples #4 and #6 do not balance within Umits. Txle remaining samplos are only . jus t within the l i m i t s .

67

WATER SAMPLES FROM PENTICTON CREEK

Sample No. 3 4 PPm epm %epm PPm epm %epm

A C1- 0.5 0.014 4.78 0.5 0.014 9.10 N Sob-- 1.0 0.021 7.06 1.0 0.021 13.u I *HC03- 15.85 0.26 88.15 7.32 0.120 77.46 0

N Sum 17.35 0.295 99.99 8.85 0.155 100.00 S C Ca++ 3 - 2 0.160 48.61 2.0 0.100 47.64 A Mg++ 1.2 0.099 30.04 0.5 O.Ct41 19.63 T Na+ 1.2 0.052 21.34 1.4 0.061 I K+ 0.7 0.018 0.3 0.008

0 N Sum 6.30 0.328 99.99 h.20 0.209 100.00

S

32.73

-

Total ppm 23 -65 13.05

1 % Anions 47 04 % Cations ePm 52.6

S.A.R. o*lhS 0.229 ~

PH 6.6 6.5 Conductivity as 27 17 mi cromhodcm Total hardness

as CaCO 13.0 6.0 3 13.0 dissolved sol ids 23.7

68

I

WATER SAPIPLES FROM PENTICTON C R m K .._I

Sample No. 5 6

PPm epm %epm PPm epm %epm A C1- 0.3 0.009 3.69 0.3 0.009 2.74

N SOL-- I HC03-

0

N Sum

1.0 0.021 9.09 1.0 0.021 6.74 12.19 0.200 87.22 17.07 0.2!8 90.52

13.49 0.229 10G.OO 18.37 0.309 100.00

S C Ca++ 3.0 0.15 3.4 0.180 49.76

A Mg++ T Na+ I K+ 0 N Sum

1.2 0.05 0.6 0.049 13.67 2.8 0.1122

0.4 0.010 36 57

7.4 0.361 io0.00

S

Tota l ppm 25 77

S.A.R. 0.36

PH 6.9 Conductivity as 20 mi cromhos/cm Total hardness

as CaCO 10.0 d i s s ~ l v e d ~ s o l i d s

6.9 36

14.0 26 37

69

WATER SAEPLES FROM PENTICTON CREEK

Sample No. 7 ~ -

PPm epm Zepm PPm epm kepm A C1- 0.50 0.014 3 =69

N SO4-- 2.70 0.056 14.71

I HC03- 19.02 0.312 81.60

0

N Sum 22.22 0.382 100.00

S C Ca++ 3.2 0.160 35.96

A Mg++ 1.8 0.148 33.33

T Na+ 2.9 0.126 30.71 I K+ 0.4 O.Ol@

0

N Sum 8.3 0.hbb 100.00

s

Total ppm 30.52

s z Anions Cations ePm

46.2 53.8

S.A.R. 0.32

PH 6.9 Conductivity as 35 m i cr omho s/cm Total hardness

as CaCO 15.6 3 dissolved so l ids 30.u

REFERENCES

Freeze, R. A . and qitherspoon, P. A., (1966): Theoretical Analysis

Analytical and Numerical Solutions to the Mathemartic k d e l ; Water Resources Research Vol. 2, #4. Effec t of Water-Table Configuration and Subsurf ace Perme- a b i l i t y Variation; Water Resources Research Vol. :3, #2.

of Regional Groundwater Flow (i)

( ii)

Freeze, R. A . (1 967) : Quanti ta t ive In te rpre ta t ion of Regional Ground- water Flow Patterns as an Aid t o Water Balance Studies; "Ground Water", General Assembly of Bern, Sept. - Oct. 1967.

(1 967) : The Continuity between Groundwater Flow Systems and Flow i n the Unsaturated Zone; Proceeding Hydrology S,vmposium No. 6, S o i l Moisture 1967.

P.F.R.A. (1 963) : Saskatoon, Geological Considerations of the Upper Penticton Creek Storage S i t e .

P.F.R.A. (1963): Water Supply and Water Use Penticton and E l l i s Creeks.

P .F .R.A. ( 1966) : Saskatoon, Preliminary S o i l Mechanics Report Penticton and Ellis Creek I r r iga t ion Projects .

T h h , J. (1 $62) : Theory of Groundwater Motion i n Small Drainage Basins i n Central Alberta; Journal Geophysical Research, Vol. 67, 811 .

? : A Theoretical Analysis of Groundwater Flow i n Small

Drainage Basins; Journal of Geophysical Research Vol . 68, E1 6.

Hall, P. L. and Laneham, E. J. (1970): Drainage Basin Study Progress Report No. 7 and Program Review; Saskatchewan Elesearch Council.

APPENDIX 1

71

Since writ ing this report , the following paper has been brought t o the author 's a t ten t ion by E. C. Halstead.

"Groundwater flow systems i n the c rys ta l l ine rocks of the Okanagan Highland, Br i t i sh Columbia", by D. H. Lawson, Canadian Journal of Earth Sciences, Vol. 4, P. 813, 1968.

This paper deals with a groundwater study i n Trapping Creek Basin, some 20 t o 30 miles e a s t of Penticton Creek Basin.

Lawson proposes a flow system based on Toth's work and proposes 6 permeability zones, three zones a re similar t o those proposed i n this repor t and a fur ther three zones of higher permeability awe postulated i n the va l ley bottom.

Lawson postulates t h a t piezometers cannot be r e l i a b l e beyond depths of 175 feet, due t o the decreasing and more random frequency of fissures with depth. He fur ther postulates an impermeable boundary a t a depth of 1000 fee t and suggests most of the groundwater movemerit (95%) occurs i n the loca l f lox system (zones KA and p a r t of KB i n t h i s report) . Lawson reports permeabili t ies higher than the P.F.R.A. figures i n this report , this may be due t o differences i n geology, there being more permeable t u f f s present i n Trapping Creek. Lawson gives values of c permeability as follows :

Local flow zones (0-150') 10-17 i g p d f t . thickness (zone KA and

Intermediate flow zone ( e s t . a t 150') 6.8 x igpdl'ft. thickness

Regional flow zone ( e s t . a t 600') 8.0 x 10"' igpd/ft. thickness

part

72

A HYDROGEOIOGICAL RECONNAISSANCE STUDY

OF PEAXSON CREEK SUB-BASIN

by P. L. Hall

73

A HYDROGEOUlG1CA.L RECONNAISSANCE STUDY OF PEARSON CREM SUB-BASIN

by P. L. H a l l

Movement Within this basin is extremely l imited due t o lack of logging roads.

There is considerably l e s s data available f o r t h i s basin than Penticton Basin.

Pearson Creek flows i n t o f i s s i o n Creek at an approximate elevation of 3,000 feet, Pearson Creek basin rises to approximately 6:,500 feet .

The basin i s considerably smaller than Penticton basin, being on17 approximately 30 square miles i n area.

Being fur ther north, precipi ta t ion i s also s l i gh t ly higher than Penticton Creek. Estimated precipi ta t ion is given below:

Contour Mean Area Precipi ta t ion In te rva l Elevation sq. Miles Inches Acre-feet

3000 - 4000' 3700 b. 2 23 5,200

4000 - 5000 L500 9.6 27 13,800 5000 - 6000 5500 11 -4 32 19,200

6000 6300 b-9 35 9 9 200 - 30.1 47, bo0

Calculations were made the same way as on Penticton Creek.

Assuming an approximate mean annual prec ip i ta t ion of sO,O@G acre-feet:

less than lo$ f a l l s below 4000 f t . more than 60% f a l l s above 5000 f t . more than 20% f a l l s above 6000 f t .

74

The. area is much the same as Penticton Creek, a Pleistocene veneer over igneous bedrock. basalta and andesites ra ther than granodiorite.

Here the main difference i s the bedrock type, being

There is a d i s t i n c t plateau area above 5,500 f e e t which is generally poorly drained, due t o the low topographic gradients. sui table f o r high l e v e l observation wells to use as an index of runoff from snowmelt. The wells should be s i t e d i n an area not influenced by large surface o r groundwater inflows and outflows. a lso, i f possible be completed i n f a i r l y permeable deposits, i.e. the drift or upper few f e e t of bedrock. affected by i r regular storage within f i s su re zones. input of water may not produce a regular r i s e i n the obsorvationwell due to zones of large permeability ( large f i ssures) and zones of small f i ssures a t d i f fe ren t depths.

T h i s area may be

The wells should

Wells completed a t depth may be That is, a uniform

It is not possible to estimate the amount of groundwater outflow from ~

the basin a t the moment as there i s no information on the type and amount of s u r f i c i a l materials i n the valley bottom. The quantity is probably i n the same order of magnitude as Penticton Creek, possibly s l l gh t ly higher as there appears to be more surficial material.

The baseflow component can be estimated from the hydrographs obtained from the new weir. the runoff hydrograph.

There is l i t t l e or no a r t i f i c i a l storage t o modify

' Movement within the basin is extremely d i f f i c u l t and it would be extremely eduponsive t o ver i fy any theor3 Licical groundwater movement by in s t a l l i ng piezometers.

Locationp of chemical annlyses are shown i n f igure 1 and r e su l t s of the water qua l i ty analyses a re shown on the Piper diagran.

00 80 50 20 - C a ++

0 0 20 8

50 80 1OC CI- - ANIONS CATIONS

PERCENT OF TOTAL EOUIVALENTS PER MILLION

Water Samples from Pearson Creek

75 WATER SAMPLES FROM PEARSON CREM

Sample No. 1 :!

epm %epm P P epm %epm PPm

A c1- 0.3 0.008 0.71 0.3 0.008 1.26 N SO4-- 4.9 0.102 8.58 2.6 0.054 8.03 I * HC03- 65.84 1.07~ 90.72 37.31 0.611 90.71 0 N Sum 71.04 1.190 100.00 40.21 0.674 100.00 S

C Ca++ 15.6 0.778 64.11 10.4 0.520 76.75 A Mg++ 3.6 0.296 24.38 1.1 0.090 13.38 T Na+ I K+

2.8 0.121 1.3 0.056 9.87 0.7 0.018 "*" 0.4 0.010

0 N Sum 22.7 1.214 100.00 13.2 0.676 100.00

S -~~ ~

Total ppm 93 74 53-41 1 % Anions % Caticns ePm 49.5

50- 4 49.9 50.1

S.A.R. o.! 66 0.1 02

PH 7.7 Conductivity as 119 micromho s /cm Total hardness

5b as CaTn dissolved so l ids 83 3

Alkalinity,as CO n i l in a l l samples. Flouride general1;y less than value obtained by multiplying CaCO by 1 .219214. 3

+ 5% for total solids 1 00 ppm. + 3% for .total sol ids 190-259 ppm. - + 2% f o r to ta l solids 250 ppm.

All samples balance within limits.

alance should bs wit;lin - -

76

t

WATER SAMPLES FROM PEARSON CREEK

Sample No. 3 4.

A C1- 0.3 0.008 1.20 0.3 0.008 0.44 N SOL-- 4.0 0.083 11-84 7 e . O 0.146 7-65 I *Hm3- 37.31 0.612 86.96 106.8 1.7'50 91.91 0 N Sum 41.61 0.703 100.00 114.1 1.904 100.00 S

C Ca++ 10.6 0.529 79.55 27.6 1.377 73.76 A Mg++ 1.0 0.082 12.37 4.5 0.370 19.82 T Na+ 1.0 0.044 2.4 0.1l04 I K+ 0.4 0.010 8o08 0.6 0.015

0 N Sum 13.0 0.665 1oo.00 35.1 1.867 S

6.42

~~ -~ ~

Total ppm 54 61 149-2

1 % Anions 51 -4 50.5 S Cations =Pm 48.6 49.5

S .A .R. 0 079 0.111

PH 7.3 Conductivity as 62 micromhos/cm Total hardness

dissolved solids 58 as CaC03 30.6

7 -9 179

87.6 112

77

A HPDROGWUIGICAL RECONNAISSANCE STUDY

OF LAMBLY CREEK SUB-BASIN

bY

E. Gordon Le Breton

A HPDR0GM)IX)GICAL RECONNAISSANCE STUDY OF LAMELY CREEK SUB-BASIN

by E. Gordon Le Breton

INTRODUCTION

Methods of Investigation

As sub-basins a re v i r tua l ly unsett led, and study of the groundwater regime must first be directed towards qua l i ta t ive reconnaissance s tudies of natural phenomena. T h i s involved f i e l d mapping of groundwater fea tures such as springs and seepage s i t e s i n re la t ion t;o topo- g r a p b and geology. A i r photos were used t o supplement f i e l d studies.

Location and Extent of the Area

Lambly Creek drainage basin occurs on the west side of Okanagan Lake, i n a d i rec t ion northwest of the c i t y of Kelowna. tween pa ra l l e l s of 1atitucJe 4YQ55' and 50°07' north, and meridians of longitude 119030' and 119 49' west (F igs . 1 and 3). basin i s about 95 square miles. Its elevation ranges from 1,121 feet a t Okanagan Lake to 6,134 f e e t a t Whiterocks Mountain.

The basin l i e s be-

The area of the

Drainage

Lambly Creek describes an arcuate course d iv is ib le i n t o 3 portions during i t s flow from Lanbly Lake t o Ckanagan Lake. source area, it flows northeast i n the upper par t , s l i g h t l y south of ea s t along i ts cent ra l portion and turns southeast i n i t s ; lowest por- t ion. The major t r ibu tary is Terrace Creek which rises i.n the extreme northwest corner of the sub-basin and generally flows southeast before entering Lamb- Creek a t about the midpoint of the cent ra l portion. Tile other important t r lbu tary creek:j a re North Lambly Creek which rises i n Tadpole Lake flowing mainly from northwest to southeaeit and occur- r i ng absct 3 &le3 west of Terrace Creek, and Bald Range Creek flowing mainly fro; north t o south e n t s r h g the main creek a t a point where it turns southeast. except a t Lambly and Espemn Lakes and by a dam on the lower p a r t of Lambly Creek. Precipi ta t ion ranges f roa a b m t 11 inches a t Okanagan Lake t o an estiriated 36 inches a t t!ie Nghss t levels .

Upon lea.ving i ts

The basin is l i t t l e affected by man made storage,

Vepetation

The area is densely forested preventing access to much of t h e area. (0 The t r e e types are-mainly Lodgepole pine with some Douglas fir and Spruce a t the higher elevations, above about 3,500 f e e t , with Douglas fir and Yellow pine predominating below 3,500 f e e t and i n areas of east-facing aspect. elevation range from about 3,000 to 4,500 fee t .

Locally poplars occur and a r e found within the

The bedrock geology is comprised mainly of two rock types, in t rus ive igneous rocks chief ly gran i te and granodiorite of Jurass ic age, and extrusive igneous rocks, chief ly andesite and basa l t of Tert iary age (Fig. 1) . These rocks, which have not been subjected to s t ruc tu ra l influences produced by ear th movements can be expected to have f rac ture pat terns formed during natural cooling processes and by weathering. Rectangular type f rac ture pat terns were observed during f i e l d work but no par t icu lar predominating trend seemed t o be apparent from which qua l i ta t ive inferences may be drawn concerning f rac ture permeability influences on groundwater movement.

79

The s u r f i c i a l geology (Fig. 2) most of which has been mapped by R. J. Fultnn (1969) consists mainly of till, an unsorted mixture of sand, silt, clay and boulders, commonly less than 25 feet, thick. Fluvial deposits of sand and gravel wi th locally some si l t , are common- l y found flanking the s teep valley faces of Lambly Creek.

\ HYDROGEQIQGY -

Groundwater Mapping

As access roads are well dis t r ibu ted i n this sub-basin, it was possible t o make observations concerning groundwater fea tures across much of the area. and fa l l , p ~ m i t t i n g observations which givo an indication of influence of seasonal vsrlat ions i n temperature and precipi ta t ion upon r a t e s of gromduater d i s c h a r p and storage. Plot t ing of basic data and i t s sub- seqnent synthesis resultod i n division of the basin in to several gmundxater zones (Fig. 3 ) . A t the highest levels from 14,500 f e e t to 4,800 fee t , zone 1, a zone of thick snow accumlation, spring and summer nel t ing gives rise t o water-logged areas, o r t e r r a in with many springs and o f t sn very widespread seopage. range of about 4,000 f e e t to 4,400 f e e t is characterized by fewer springs and somewhat l e s s seepage. Zones 1 and 2, the source and near source areas f o r creeks give rise to permanent runoff and most of the

Nunn,rous t r i p s wepe m d c in to the basin betwcen ear ly summer

Zone 2, i n an elevation

80 groundwater discharge. Spring discharges are commonly less than 2 imperial gallons per minute - and many of n e spring discharges do not become p a r t of t :he main s treamflow .

These are zones of considerable water surplus.

There appears to be considerable groundwater and surface water that is l o s t by evapotranspiration so that much of the prec ip i ta t ion is involved i n a hydrologic cycle that is complete a t these high levels . A t successively lower elevations than zones 1 and 2, are zones 3, 4 and 5 with an ever decreasing number of spring discharge s i t e s and seepage features .

Locali ty LA was so separated because of the rare occurrence of a permanent, nearly constant flowing spring of about 2 i g p m (imperial gallons per minute). T h i s spring observed many times during the f i e l d season, showed no noticeable drop i n y ie ld i n contrast t o most springs many of which went dry or nearly dry. ou t a pa r t i cu la r ly la rge catchment area, i t s west-facing aspect combined with possible high storage may account f o r its steady flow.

Occurring on a s t eep slope with-

Water Quant i ty

There is no informatdon avai lable concerning permeability of the bedrock nor s u r f i c i a l deposits f o r Lanbly Creek sub-basin.

Recourse therefore nust be made to texts discussing data on the same rock types occurring elsewhere. For information on g ran i t i c and b a s a l t rock types, reference is made t o Meinzer (1923, p. 138 t o 148). Grani t ic type rocks a re generally poor water bearers and when encountered a t several hundred feet, are almost devoid of water. obtained from j o i n t openings which may be expected t o close rapidly with depth. rock a r e less than 300 f e e t deep, most of the water supp1.y coming from d q t h of l e s s than 100 f ee t . Woll yie lds range from 2 $XI 25 igpm and average about 10 igpn.

Water is

The vast majority of wells producing water fTrom g r a n i t i c

Well yields and spring flow from basa l t s prove this rock type to be a good aquifer i n the United S ta tes . openings and other cavi t ies . l a rge openings that it takes i n surface water very readily." (Meinzer, 1923, p 1 38). anticipated. In areas favourable t o high wel l yield, s imi la r ly high spring flows are to be expectsd a:id do, i n f a c t , occur.

"The water occurs i n large j o i n t This rock is so generally traversed by

Frequently, well yields up to 100 igpm may be

Within the wr i t e r ' s l imited f i e l d cbservations, no evidence was found of spring flow from bedrock sources. generally lox permeability and low ;later y i e ld of the bedrock i n the basin. sources within the Okariagan, is given by Halstead, E. C. (1969) and

This may be taken to suggest

Information :orLfi=.ming generally low w e l l yie lds from bedrock

81 from an observation well d r i l l e d in to volcanic rocks i n Pearson Creek sub-basin i n 1970 and supervised by the Groundwater Division. programs, examples, from wells t o as deep as 270 f e e t show well yields from several. small f ractures to be i n t h e range of 1 t o less than 10 igpm.

Both

With regard t o the s u r f i c i a l deposits these a re primarily till, and again a r e predominantly low permeability materials. The common occurrence concerning groundwater discharge is mainly of spring seepage with some spring f lows l e s s than 2 igpm. The f a c t that there :Ls noticeable decrease i n flow, some of which cease en t i r e ly and of considerable decreases i n size of spring seepage areas from spring to f a l l suggests generally low groundwater f lov from the s u r f i c i a l deposilx. T h i s very noticeable decrease i n groundwater discharge is evidence of the depend- ence of storage areas upon replenishment by snowmelt and of the l imited storage capacit ies of the material from which discharge takes place.

As the objective of the sub-basin s tudies was t o assess, even on a qua l i ta t ive basis, the possible importance of the groundwater component to stream flow, it i s believed t h a t most of the groundwater t o stream flow originates i n the source areas of zone 1. r ived mainly from the s u r f i c i a l deposits and possibly from shallow depths i n the bedrock. Almost a l l of the water supply leaving the basin is considered measured by runoff gauges and losses beneath and

The groundwater i s de-

around gauging

Water Qual i ty

si tes is thought t o be minor.

Numerous conductivity measuements of springs and stream flow wer

mho/cm a t 2 9 C , Todd, 1959, p. 328). ed show a s teadi ly increasing ninoral content with increasing flow path. Very high elevation areas, areas of groundwater recharge, have waters low i n tot31 dissolved sol ids and low elevation areas, discharge areas have waters higher i n t o t a l dissolved sol ids . streams and groundwaters (springs) show the same trend. The increase i n minorallzation is ccmonly small, fur ther suggesting that groundwater contributions to runoff a r e mall.

plo t ted a3 parts per r s l l i o n (conversion fac tor 1 ppm 1 .!% x 1 o f : . The p la t ted results when contour-

Both surface

82

I -

REFERENCES CImD

Halstead, E. C. (1 969) : Groundwater Investigation, Mount Kobau, B. C., Inland VatersBranch, Department of Tech. B u l l . Series No. 17.

Energy, Mines and Resources.

Survey Water Supply Paper 494. Meinzer, 0. E. (1923):

Todd, D. K. (1959):

Outline of groundwater hydrology; U. S. Geol.

Groundwater Hydrology; John Wiley &nd Sons, New York.

83

A HYDR0GM)UGICAL RECONNAISSANCE STUDY

OF GREATA CREEK SUB-BASIN

bY E. Gordon Le Breton

A HYDROGEDLOGICAL RECOlOIAISSANCE STUDY OF GREATA CREEK SUB-BASIN

by E. Gordon Le Breton

INTRODUCTION

Methods of InvestiRation

A s sub-basins a re virtually unsett led, any study of the groundwater regime must f i r s t be directed towards qua l i ta t ive reconnaissance s tudies of natural phenomena. T h i s involved f i e l d mapping of groundwater features such as springs and seepage s i t e s i n re1at;ion t o topography and geology. A i r photos were used t o supplement f i e l d studies.

GM)GRAPHY

General Comments

Greata Creek sub-basin lies between i i n e s of l a t i t ude 49"45' and 49°49' north and meridians of longitude 119 51 ' and 12000' west. total area of about 12 square miles. This sub-basin is closely comparable with the Lambly Creek aub-basin where Lambly Creek flows within its upper and central portions, i n terms of topography, direct ion of stream flow and aspect. Greata Creek flows from southwest to northeast and turns e a s t to flow in to Peachland Creek. The basin has an east- facing aspect (Fig. I ) .

It has a c

GEDIDGY

General Comments

The bedrock geology as shown i n Figure 1 taken from G.S.C. Map 5388, Kettle River (uest half), geology by Cabnes, C. E. (1936) consists primarily of granodiorite, d io r i t e and quartz d i o r i t e rock types.

The s u r f i c i a l geology (Fig. 2 ) i s mainly till, commonly qui te th in across much of '&e area with sand and gravel deposits flanking and underlying Greata Creek. to be up to 50 feet thick.

The thickness of theso deposits i s estimated

HYDROGEOLOGY

As Greata Creek covers a very small area and was mapped during a shor t time in t e rva l i n the summer a f t e r the influences of snowmelt had large- ly disappeared, it was possible t o observe only a l imi ted number of groundwater features . This basin l i e s a t an elevation range equivalent t o zones 3 and 4 of a b l y Creek sub-basin and may e a r l i e r i n the year exhibi t more numerous s i t e s of seepage and spring discharge. Becsause of the time of year a t which this basin was mapped, i t s more southerly location, and the small number of groundwater discharge points actual ly observed, the basin zones a re c lass i f ied a s s imilar to zones 4 and 5 of Lambly Creek.

Increases i n stream flows are generally associated with additional t r ibu tary creeks entering the main creek. appearing stream, the most northwesterly t r ibu tary creek, revealed an overa l l increase i n flow, some of which might possibly be a t t r ibu ted t o groundwater discharge. there i s l i t t l e evidence t o suggest more than minor contributions from groundwater t o the increase i n stream flow. increase i n total mineralization of the streams with increased flow path (Fig. 3) supporting the f a c t t ha t some increment from groundwater was mado to stream flow.

However, an intermit tent ly

However, as i n the case of Lambly Creek,

Again there was some small

CONCLUSIONS

Conclusions drawn from the study of the two foregoing sub-basins are t h a t most of the discharge of water from the basins i s measured as runoff. very small and would form a very small percentage of the t o t a l runoff of both basins.

The amount of groundwater flow which goes m e a s u r e d is probably

' .-

86

SUB-BASIN STUDY CONCLUSIONS

I n summing up the combined findings of the s i x sub-basin s,tudies, '

Mr. Halstead's phrasing of the objective w i l l be repeated.

Objective

"The object of the reconnaissance investigation was t o deLermine whether o r not the groundwater component of the sub-basin i s i n su f f i c i en t volume t o warrant the expenditure of more time and funds to provide a s complete as possible an assessment of its contribution t o the hydrologic regime."

Certain common fac tors emerge from three separate investigators:

( 1 ) Geolopy

The bedrock geology comprises mainly intrusive igneous rocks -- grani te and granodiorite; metamorphic rocks -- gneiss and schis ts ; and extrusive igneous rocks -- andesite and basal t .

The s u r f i c i a l geology i s primarily till, commonly very thin, with some sand and gravel.deposits i n each basin. a r e the most important medium f o r storage and movement of groundwater.

The s u r f i c i a l deposits (0 Topography

' There is generally a sharp change i n surface gradient fro:m the mouths of the main creeks to the i r source areas.

( 3 ) Vegetation

Dense stands of timber prevent access t o much of the basin areas. The main t r e e type is Lodgepole pine with some .Douglas f i r , Spruce, Yellow pine, Poplar and Cedar.

( 4) Hydro geo l o gy

Sharp changes i n gradient, and bedrock-drift contacts give rise t o the occurrence of many springs i n the basins.

Local flow systems p r h a r i l y occurring within the s u r f i c i a l deposits adjacent to the creeks account f o r most of the groundwater component of baseflow. depth and small a rea l extent, they a re sources of small groundwater storage. decline i n yield and is very dependent on recharge fo r maintenance of

Because loca l flow systems a re primarily of' l imited

Consequently, much of the grmdwater discharge: w i l l rapidly

87 flow. As recharge is r e s t r i c t e d almost en t i r e ly . to snowmelt, a high and steady rate of groundwater discharge must not be expected from the sub-basins.

Baseflow to t h e streams is calculated t o range from 3 to 20 c f s f o r Vasew and Penticton Creek drainage basins. It i s considered to be equally small f o r the other sub-basins with t h e i r very s imilar hydrogeological environments.

( 5 ) Hydrogeochemistry

There i s an increase i n t o t a l dissolved so l id s content of surface waters and groundwaters from the recharge t o discharge areas, but t h i s increase i s not very s igni f icant .

Only small increases i n t o t a l mineralization to streams seen i n conjunction with only l imited increases i n stream-flow support early opinions that the nature of the bedrock and sur f ic l .a l geology was such that considerable groundwater contributions should not be ant ic ipated from sub-basins.

(6) Conclusions

Inaccuracies i n measurement of prec ip i ta t ion across the basins, t h e very few prec ip i ta t ion gauges occurring i n these areas, combined with general extrapolation of the data across the basins and its divergence from actual prociki ta t ion variations, more than o f f s e t e r rors i n groundwater flow calculations.

It i s generally agreed t h a t instrumentation f o r fu r the r groundwater s tud ies i n sub-basins within the ra ther l imited budget f o r the Okanagan River Basin Study seems unjus t i f ied a t t h i s time. Instru- mentation if carr ied out i n the future should follow that outlined by P. L. Hall. The wri ter , based on h i s f i e l d observations suggests Terrace Creek as a minor basin f o r fu r the r study ( 1 ) because of the many creeks with readi ly available access, ( 2 ) the r e l a t i v e ease with which gauging s ta t ions could be reached, ( 3 ) t he very l imited amount of man-nade storage i n the basin.

I n r e l a t ing sub-basin s tud ies to tho groundvater s tudies i n the main valley, it can be observed t h a t subsuri’ace flows i n t o f a n deposits a t the mouths of t r ibu tary creeks, though possibly commonly small, may provide loca l ly important sources of groundwater recharge. strong evidence t o suggest subsurfaco flow from tr ibutary val leys augments stream flow i n Okanagan River a t the south end of the valley.

There i s

8 Miles

LEGEND

OKANAGAN DRAINAGE BASIN ---- LOCATION OF TEST DR1,LLING AND SEISMIC WORK

*/.--.- SUB-BASIN’STUOY AREAS e--/.> 0

h

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DEPARTMEMT OF LAIDS, FORESTS, AND WATER RESOURCESa100.gov.bc.ca/appsdata/acat/documents/r4438/270_114142750598… · with the drilling bcing done by Big Indian Drilling Company Limited