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DEER CREEK PROJECT

FEASIBILITY REPORT

Volume I - Report

STATE OF WYOMING

WYOMING WATER DEVELOPMENT COMMISSION

ORLANDO, FLORIDA

WELLESLEY, MASSACHUSmS

SACRAMENTO, CALIFORNIA

R. W. BECK AND ASSOCIATES ENGINEERS AND CONSULTANTS

SEATTLE, WASHINGTON

DENVER, COLORADO

PHOENIX, ARIZONA

FEBRUARY 1984

COLUMBUS, NEBRASKA

INDIANAPOLIS, INDIANA

MINNEAPOLIS, MINNESOTA

PLANNING DESIGN RATES

R. W. BECK AND ASSOCIATES ENGINEERS AND CONSULTANTS

TOWER BUILDING GENERAL OFFICE

SEATTlE, WASHINGTON

ENVIRONMENTAL ECONOMICS MANAGEMENT

7TH AVENUE AT OLIVE WAY

SEATTLE, WASHINGTON 98101

206-622-5000

Telephone: 206-622-5000

Telex: (1TT)4990402

FILE NO.

HH-2312-WR1-AA 3110

Mr. Jon W. Wade Wyoming Water Development Commission Barrett Building Cheyenne, Wyoming 82002

Dear Mr. Wade:

February 17, 1984

Subject: Deer Creek Project Feasibility Report

We herewith submit our Feasibility Report on the Deer Creek Proj-ect. This report summarizes the results of engineering and economic studies made for the Deer Creek Project subsequent to the Interim Report dated Decem-ber 1982. Principal findings, conclusions, and recommendations are set forth in the summary of the report. Details of the engineering and economic studies are summarized in the body of the report.

The work described in the report was authorized by the Commission in its Contract for Services dated September 8, 1982.

(B7795A) Enclosures

Very truly yours,

R. W. BECK AND ASSOCIATES

('/ James V. Williamson . Partner and Manager

Hydro-Water Resources Design Ottice

Seattle, WA • Denver, CO • Phoenix, AZ • Orlando, FL • Columbus, NE • Wellesley, MA • Indianapolis, IN • Minneapolis, MN • Sacramento, CA

CERTIFICATE OF ENGINEER

DEER CREEK PROJECT FEASIBILITY REPORT

The technical material and data contained in this report were com-piled by the following engineers: John H. Dixon, P.E.; Stephen M. Hart, P.E.; William M. Verig1n, P.E.; J. R. Reed, P.E.; and James R. Stevenson.

The technical analyses, material and data developed in this study were prepared under the supervision and direction of the undersigned, whose seal as a professional engineer is affixed below •

.......... • - R ••

•• - \.\)'NA D ,fly. '. ;~~w~ .. ~·· • • ~ ."~«' o~.. c.& • :~i~ ~\~\ : : en 4377 (,') ! S . \ , . • - I • . ~ ..

• .-0 -.. ~~ ....& ~. ~ • • ~h •.• GISTE"': •• .!t..~ • • ~I; ........... ~-", ~.rIONAl \'f.() •• -" .-••••••••

James E. Alverson Registered Professional Engineer

state of Wyoming

VOLUME 1

VOLUME 2

DEER CREEK PROJECT

GENERAL OUTLINE OF FEASIBILITY REPORT

REPORT

APPENDIX A - PRELIMINARY ASSESSMENT OF PERMIT REQUIREMENTS

APPENDIX B - RESULTS OF RESERVOIR OPERATION STUDY APPENDIX C - BACKGROUND INFORMATION - NORTH PLATTE

RIVER WATER RIGHTS - EFFECT ON PROJECT YIELD

APPENDIX D - CONSTRUCTION COST ESTIMATES, ALTERNATIVE DAM TYPES

APPENDIX E - CONTROL AND TOPOGRAPHIC SURVEYS APPENDIX F - GEOTECHNICAL REPORT

Section Number

I

II

III

DEER CREEK PROJECT

FEASIBILITY REPORT

TABLE OF CONTENTS

Section and Subsection Title

Letter of Transmittal Certificate of Engineer General Outline of Feasibility Report Table of Contents List of Tables List of Figures List of Appendices Summary

INTRODUCTION 1. 2. 3. 4.

Authorization Project Location Interim Report Scope of Services

FLOOD CONTROL ANALYSIS 1. Introduction 2. Flood Control Hydrology

a. General b. Procedures c. 100-Year Peak Flood at Glenrock d. lOO-Year Peak Flood at the Dam Site

3. Preliminary Design of Flood Control Facilities 4. Cost of Flood Control Features 5. Economics of Flood Control

RESERVOIR OPERATION STUDIES 1. Introduction 2. Virgin Flow Record 3. Storable Flows 4. Water Yield 5. Project Effects on the North Platte River

IV NORTH PLATTE RIVER WATER RIGHTS -EFFECT ON PROJECT YIELD 1. 2. 3.

Introduction The North Platte System USBR Study

Page Number

1-1 1-1 1-1 1-3

11-1 11-1 11-1 11-2 11-3 11-4 11-4 11-6 11-6

111-1 111-2 111-4 111-6 111-7

IV-l IV-2 IV-3

Section Number

IV

V

VI

TABLE OF CONTENTS (continued)

Section and Subsection Title

NORTH PLATTE RIVER WATER RIGHTS -EFFECT ON PROJECT YIELD (continued) 4. Reservoir Yield Based on Surplus River Water 5. Additional Studies Needed

SUMMARY OF GEOTECHNICAL INVESTIGATIONS 1. 2. 3. 4.

5.

6.

Regional Geology Site Geology Field Investigations and Materials Geology of Project Features a. Dam and Outlet Works b. Spillway c. Reservoir Construction Materials a. Concrete Aggregate b. Embankment Materials Engineering Requirements a. Dam Foundation and Treatment b. Foundation Excavation c. Reservoir Seismicity a. Faults b. Earthquake History c. Site Acceleration

PROJECT ALTERNATIVE ARRANGEMENTS 1. General 2. Type of Dam

Testing Program

3. Spillway Requirements and Dam Crest Elevation

VII DESCRIPTION OF SELECTED PROJECT 1. 2.

3. 4. 5. 6. 7. 8.

General Dam a. Dam Section b. Dam Crest Spillway Reservoir Outlet Works Access Project Land Ownership Diversion During Construction a. General b. Construction Sequence

Page Number

IV-4 IV-5

V-1 V-1 V-3 V-4 V-4 V-5 V-5 V-5 V-6 V-7 V-8 V-8 V-9 V-9 V-9 V-9 V-10 V-10

VI-1 VI-1 VI-4

VII-l Vl1-1 V11-l VI1-2 V11-2 VII-3 VII-4 VII-5 V11-6 VII-6 V11-6 VII-7

Section Number

VIII

IX

X

TABLE OF CONTENTS (continued)

Section and Subsection Title

PROJECT COST AND SCHEDULE 1. General 2. Cost Estimate

a. Direct Construction Cost b. Contingency c. Engineering and Owner Administration d. Total Construction Cost e. Escalation f. Interest During Construction g. Total Investment Cost (TIC)

3. Design and Construction Schedule a. Advanced Engineering and

Environmental Studies b. Design and Construction c. Startup and Operation

ECONOMIC ANALYSIS 1. Introduction 2. Annual Cost of the Project 3. Economic Analysis for Scheduled Increase

in Project Water Sales a. Water Demand Schedule b. Cost of Alternative Water Supply

4.

c. Other Benefits d. Comparison of Results and

Internal Rate of Return Economic Analysis Based on Yield

Fully Committed in 1990

CONCLUSIONS AND RECOMMENDATIONS 1. Conclusions

a. Purpose and Yield b. Geotechnical Considerations

Project Design c. Costs and Schedule

2. Recommendations

and

XI REFERENCES

Page Number

VIII-1 VIII-1 VIII-1 VIII-2 VIII-2 VII1-3 V111-3 V111-3 V111-3 V111-4

V1I1-4 V111-4 V111-5

1X-1 1X-2

1X-3 1X-3 1X-6 1X-7

1X-7

1X-8

X-1 X-1

X-2 X-3 X-3

Table Number

11-1 11-2

111-1 111-2 111-3 111-4 111-5 111-6 111-7 111-8

IV-1 IV-2

IV-3

IV-4

VI-1

VII-1

VIII-1 VII1-2

LIST OF TABLES

Title

Flood Control Capabilities for 100-Year Flood Flood Control Capabilities for Historical Flood of May 1965

Historical Monthly Flow Recorded by USGS at Glenrock Comparable Gage Record at Glenrock - Scenario 2 Physical Inflow to the Reservoir - Scenario 1 Physical Inflow to the Reservoir - Scenario 2 Storable Flow at the Reservoir - Scenario 1 Storable Flow at the Reservoir - Scenario 2 New Flow into North Platte - Scenario 1 New Flow into North Platte - Scenario 2

Estimate of Surplus North Platte River Water Estimated Storable Flow at the Reservoir as Limited by Surplus River Water (Scenario 2) Estimated Firm Yield as Limited by Surplus River Water (Scenario 2) Estimated 80% Chance Yield as Limited Surplus River Water (Scenario 2)

Cost Comparison of Alternative Dams

Estimated Rockfill Material Requirements

Total Investment Cost Construction Cost Estimate - Concrete-Faced Rockfill Dam

IX-1 Assumptions Used in Estimating Annual Cost IX-2 Capital and Annual Cost IX-3 Annual Cost by Year - 1989-2018 1X-4 Projected Water Demand Schedule IX-5 Cost of Alternative Source of Water IX-6 Annual Benefits IX-7 Summary of Economic Analysis

Figure Number

1 2 3 4 5 6 7 8 9

10 11 12 13

LIST OF FIGURES

Title

Location and Vicinity Map Unit Hydrographs and 100-Year Flood at the Dam Site May 1965 Flood Hydrographs Project Geology and Borrow Exploration Plan Dam Site Geology Reservoir Area and Access Alternative Arch Dam Alternative Earthfill and Concrete-Gravity Dam Sections Recommended Project Arrangement Outlet Works PMF and Spillway Design Flood Area-Capacity Curves Design and Construction Schedule

Appendix

A B C

D E F

LIST OF APPENDICES

Title

Preliminary Assessment of Permit Requirements Results of Reservoir Operation Study Background Information - North Platte River Water Rights -Effect on Project Yield Construction Cost Estimates - Alternative Dam Types Control and Topographic Surveys Geotechnical Report

S~ARY

The 1982 Session of the Wyoming State Legislature authorized a

Level II Feasibility Study of the Deer Creek Project (Project). The Wyoming

Water Development Commission (wwnC) in October 1982 selected the firm of

R. W. Beck and Associates (Beck) to perform the study.

In the initial phase of the study, Beck prepared an Interim Report,

issued in December 1982, which shows a need in the Casper, Glenrock, and

Douglas area by about 1990 for additional municipal and industrial water sup-

ply. The report explores alternatives for developing a reservoir in the Deer

Creek Basin to serve those needs. That report recommended that a reservoir

located at the upper end of the Lower Deer Creek Canyon (Canyon) with a maxi-

mum normal water level at El 6700 which would develop 61,000 ac-ft of water

supply storage capacity should be studied at a feasibility level of detail.

At that time, a preliminary estimate indicated the firm yield of the reservoir

would be about 17,600 ac-ft/yr. WWDC concurred in the recommended location

and size of the reservoir and directed Beck to proceed with the feasibility

study.

Conclusions and Recommendations

The feasibility report presents results of studies which

demonstrate that the Project can provide a firm yield between 4,050 to

16,000 ac-ft/yr to meet the Casper, Glenrock, and Douglas area's water supply

needs at an estimated capital cost of $47.6 million, based on completion in

November 1988. Additional studies are needed to establish the amount of Proj-

ect yield with adequate precision. Based on the higher limit of yield, the

Project can supply these needs at approximately 30~ to 40~ of the cost (on a

per ac-ft basis) of the least costly logical alternative. This alternative is

the Little Snake River Water Management Project (Stage III).

Page 2

For the above reasons, it is recommended that the State undertake

the following actions: first, conduct legal research and hydrologic and oper-

ation studies to establish the yield of the Project. If Project economics

remain favorable based on this refined estimate of yield, authorize construc-

tion of the Project and initiate the next stage of Project development. Such

work would include collection of environmental data, preparation of an envi-

ronmental report, and performance of additional geotechnical exploration as a

basis for refinement of the feasibility designs and cost estimates.

Flood Control Analysis

Flood damages have occurred historically in the area along Deer

Creek between the Project dam site and the North Platte River. A study was

made to determine if facilities should be incorporated into the Project design

which would prevent or reduce such damages. Based on the flooding resulting

from a derived 100-year fequency flood, it was found that flood damages could

be reduced by an estimated $40,000 per year if specific flood control facil-

ities were included and that without specific facilities, Project operation

would result in incidental damage reduction of about $25,000 per year.

The estimated annual costs of the flood control features are about

ten times the incremental annual damage reduction of $15,000. It is con-

cluded, therefore, that specific flood control features are not economic and

are excluded from the Project.

Reservoir Yield

The range of Project yield available to meet municipal and indus-

trial water supply was estimated based on operation studies of the reservoir

and considering limitations to Project storable flow as imposed by legal con-

straints. Legal constraints consist of water rights entitlements in the Deer

Page 3

Creek and North Platte River basins as provided by Wyoming law and the U.S.

Supreme Court North Platte Decree as amended in 1952.

Two scenarios were developed in considering the storable flow as

limited by water rights in the Deer Creek Basin. The first (Scenario 1) is

based on flow available for storage in the reservoir after irrigation has been

provided from natural flow or irrigation return flow to the 3,400 acres along

Deer Creek which historically have been irrigated. The second (Scenario 2) is

based on the flow available for storage after supplying the 6,400 acres hold-

ing permitted water rights.

Project storable flow as limited by water rights in the North

Platte Basin was developed using results of a U.S. Bureau of Reclamation

(USBR) study which derived conservative estimates of flow that are surplus to

the needs of the Basin area which receives flow within Wyoming. In the analy-

sis, that part of the river flow originating at the Project that is surplus to

the requirements of both Deer Creek and the North Platte Basin is considered

storable.

Based on the storable flow estimates, reservoir operation studies,

and considering Scenario 2 for Deer Creek, the range of Project yield is as

follows:

Storable Flow Condition

Considering Deer Creek Water Rights Only ••••••••••••••• Considering Deer Creek and North Platte Water Rights •••

Firm Yield (ac-ft/yr)

16,000 4,050

The true firm yield of the Project lies wi thin the above range.

Additional legal and hydrologic studies will, however, be necessary to estab-

lish the exact amount of yield.

Page 4

Project Layout

Based upon the results of the geotechnical investigations and stud-

ies of alternatives, a selected Project arrangement was developed which in-

cludes the following features:

o A concrete-faced rockfill dam 275 feet in height above the founda-

tion and with a crest length of 900 feet.

o A reservoir about 2 miles long with a normal maximum water surface

at EI 6700. The surface area at this elevation is 1,050 acres.

The reservoir would have a water supply storage capacity of

61,000 ac-ft above the minimum pool level (EI 6540).

o An unlined overflow spillway with concrete crest located in a rock

cut on the right abutment of the dam designed for a flood with a

return interval of about 500 years, and capability to safely pass

the probable maximum flood (PMF). Geotechnical investigations con-

clude that the granitic rock present in this area is adequate for

this spillway arrangement.

o An outlet works conSisting of an intake structure, a 10-foot-

diameter steel-lined reinforced concrete conduit under the dam, and

a valve control house. The conduit would bifurcate downstream of

the dam and would be equipped with two 54-inch Howell-Bunger valves

for energy dissipation.

o Access to the dam and reservoir would be provided by reconstructing

and upgrading 10.5 miles of existing road and constructing 1 mile

of new road.

Page 5

Project Cost and Schedule

The estimated capital cost of the Project is $47,600,000, based on

Project completion in November 1988 and commercial operation beginning in July

1989. This estimated cost includes allowances for escalation, and Interest

During Construction charged at 10%. This estimated cost would correspond to a

cost of $33,700,000 if construction had been started so as to bring the Proj-

ect on-line in January 1983.

The projected in-service date of July 1989 for initial water deliv-

eries considers that the reservoir would be operational in time to allow stor-

age of the 1989 spring runoff, and requires award of the main construction

contract by April 1986. The above schedule can be met if a decision to imple-

ment the Project were made in sufficient time so that the next phase of engi-

neering can begin by June 1984.

Cost of Water and Economic Analysis

Studies of the cost of Project water and the economics thereof are

based on a firm yield of 16,000 ac-ft as determined from Scenario 2 consider-

ing Deer Creek water rights only. These studies indicate, based on a July

1989 in-service date and 10J financing, that the estimated first-year annual

cost of Project water delivered at the reservoir would be $4,791,000 and the

cost per ac-ft would be $299. The corresponding per ac-ft cost if the reser-

voir had been constructed for service beginning in January 1983 would be

$212/ac-ft.

Two economic comparisons were developed based on supplying to the

ci ties of Casper, Glenrock, and Douglas their projected water demands occur-

ring after 1989 using the internal rate of return method of analysis for com-

paring Project costs and water supply benefits. The first comparison assumes

that the Project yield would be sold based on a continuing increase in water

supply requirements between 1989 and 2012. The second assumes that the yield

Page 6

would be fully committed at the time of initial Project water deliveries in

July 1989. Project financing at interest rates of 8.5J, 10J, and 12J was used

for each analysis along with an inflation rate of 6J.

Water- supply benefits are considered equivalent to the cost of

water supplied by the least-cost logical alternative source, which is consid-

ered to be the Little Snake River Water Management Project (Stage III). In

both analyses, the Project is shown to provide a more economical water supply

than the alternative project for all reasonable interest rates. Benefit/cost

ratios would be in the range of 2.7 to 2.9 for the first analysis, and 2.6 for

the second analysis for interest rates ranging from 8.5J to 12J.

These analyses indicate that the Deer Creek Project will be an

economical source of municipal and industrial water supply for all reasonable

interest rates if the Project firm yield is close to 16,000 ac-ft/yr.

SECTION I

INTRODUCTION

1. AUTHORIZATION

The 1982 session of the State Legislature authorized a Level II

Feasibility Study of the Deer Creek Project (Project), and appropriated funds

for the study to be carried out by the Wyoming Water Development Commission

(WWDC). Subsequently, WWDC entered into a contract with R. W. Beck and Asso-

ciates (Beck) dated September 8, 1982 to provide engineering services for con-

ducting the study.

2. PROJECT LOCATION

Deer Creek is a tributary of the North Platte River, which it joins

at the City of Glenrock. This confluence is located approximately 21 miles

east of the City of Casper and 25 miles west of the City of Douglas. The Deer

Creek Basin (Basin) is situated primarily in Converse County except for the

western one-quarter which is in Natrona County. The Basin is accessible from

Interstate 25 and local roads. Figure 1 shows the geographical relationship

of the Basin to the cities of Casper, Douglas, and Glenrock.

3. INTERIM REPORT

Presently, runoff from Deer Creek is used to satisfy existing irri-

gation water rights and for municipal and industrial water supply at Glen-

rock. Water appropriated under these rights is utilized within the Basin and

along the North Platte River in Wyoming and Nebraska. Previous reports have

identified the Basin as being a prime area for water resources development.

The latest of those reports is the Deer Creek Project Interim Report prepared

I-2

by Beck on behalf of WWDC in December 1982. That report, which is based on

appraisal-level studies, includes information on the following topics:

a. Physical description of the Basin.

b. Summary of the Basin's climatology and hydrology including an esti-

mate of the Probable Maximum Flood (PMF). Also described is a

mass-curve analysis of runoff which was used to prepare a prelim-

inary estimate of the Project yield and storage requirements.

c. Summary of the water resources needs which might be supplied from a

reservoir on Deer Creek. These include municipal and industrial

water supplies for the Casper, Glenrock, and Douglas area, supple-

mental irrigation water supply in the Basin, and reduction of flood

damages.

d. Results of a Basin-wide study to identify and appraise alternatives

for water resources development. Alternatives considered include

construction of reservoirs situated on the Deer Creek main stem and

on tributary streams, and acquiring existing water rights. A res-

ervoir on Deer Creek located at the upper end of the Lower Deer

Creek Canyon (Canyon) was selected as offering the best opportunity

for water resources development.

e. A summary of stUdies of reservoir development at the selected site

in the Canyon. Those studies indicate that a project having the

following characteristics would be most economical:

Location of dam •••••••••••••••

Type of dam ••••••••••••••••••• Normal maximum water supply

storage level ••••••••••••••• Water supply storage volume ••• Water supply firm yield ••••••• Minimum (dead) storage level •• Minimum (dead) storage volume •

Upper end of the Lower Deer Creek Canyon

Embankment

El 6700 61,000 ac-ft 17,000 ac-ft/yr El 6540 5,000 ac-ft

1-3

The Interim Report recommends that a reservoir located at the site

described in d. above, and with the stated storage levels and capacities, be

studied at a feasibility level of detail. WOC, in its letter to Beck of

February 25, 1983, expressed its concurrence in this recommendation. The Com-

mission also agreed that studies pertaining to the purchase of water rights

and groundwater development in the Deer Creek floodplain as discussed in the

Interim Report should not be pursued further.

4. SCOPE OF SERVICES

The primary purpose of this report is to document and summarize the

feasibility-level studies performed for the Project as authorized by WWDC's

let ter of February 25, 1983 cited above, and in accordance with the scope of

services as contained in Beck's September 8, 1982 Contract (Contract) with

WOC as summarized below. This report is designed to complement information,

data, and results contained in the Interim Report and will not repeat informa-

tion presented in that report except as necessary for clarity.

Each of the items of work described in Exhibit A to the Contract is

addressed in either the Interim Report or this report. The Interim Report was

structured to address work items 1 through 4 and a part of the flood analysis

required by work item 6. This report addresses the requirements of work

items 5 through 11 which are summarized as follows:

o Work Item 5

This work item provides for a geotechnical investigation of the

selected Project site and reservoir area and development of

feasibility-level designs, cost data, and other information. The

geotechnical investigations will consist of drilling, sampling, and

testing to evaluate the physical properties of the dam foundation,

exploration and testing to identify adequate sources of construc-

tion materials, geologic evaluation of the proposed reservoir area

1-4

to identify potential landslides, induced seismicity, and potential

for reservoir seepage through the underlying formations, and

preparation of a geotechnical report. In addition, based on

feasibility-level designs, a Project summary shall be prepared

which will include a complete construction cost estimate for the

dam and all appurtenances, an estimate of Project life, the alloca-

tion of cost to Project functions, the per ac-ft annual cost of

municipal water supply, the per ac-ft annual cost of supplemental

irrigation water, an estimate of Project benefits and benefit! cost

ratio, and an estimate of the date when a new water supply project

will be necessary.

o Work Item 6

This work item provides for a hydrologic analysis which includes a

review of previous Deer Creek hydrologic studies, assessing the

impact of Project construction on existing water rights, operation

studies to estimate the range of Project yield and firm yield,

flood analyses including estimates of peak flow of record, maximum

flood volume of record, 100-year flood peak volume and the PMF, and

an estimate of annual reservoir sedimentation. The review of the

previous hydrology studies and the PMF analyses have been summa-

rized in the Interim Report.

o Work Item 7

This work item provides for a preliminary assessment of the Federal

and State permits that may be required for construction of the res-

ervoir.

1-5

o Work Item 8

This work item requires base-line environmental research necessary

to meet the requirements of Federal and State agencies, but is con-

sidered to be only that research necessary to make permit applica-

tions needed, if any, to complete this feasibli ty study. It does

not include research needed for an environmental impact statement

(EIS). Aquatic and terrestrial impact research is to be done by

the Wyoming Game and Fish Commission.

o Work Item 9

This item provides for assistance to WWDC in conducting public

workshops and meetings.

o Work Item 10

After consultation with WWDC, confer with affected landowners and

Federal land management agencies regarding issues relating to

right-of -way easements, land purchases, and other land acquisition

activities.

o Work Item 11

This item requires preparation of an economic analysis for each

potential Project option and its affect on agriculture.

Work items 1 and 8 deal with permit requirements and base-line

environmental research for permit applications. Since these items do not

affect the results of the feasibility studies, they are summarized in Appen-

dix A rather than in the main report.

SECTION II

FLOOD CONTROL ANALYSIS

t. INTRODUCTION

An analysis to determine the feasibility of including flood control

facilities as a part of the Project is summarized in this section. In gener-

al, the analysis consists of estimating the 100-year frequency flood at the

dam site and at Glenrock, designing flood control outlet facilities through

the dam and determining the effect of these facilities in reducing peak flows

resul ting from the 100-year flood and flood damages downstream of the dam.

Based on a comparison of the monetary value of reduction in flood damages

attributed to the flood control facilities and the costs of such facilities,

the economics of incorporating flood control as a Project function is deter-

mined.

A flood damage analysis for the Basin is summarized in the Interim

Report. The results of that analysis (Fig. 8 of the Interim Report) are used

herein to estimate the monetary value of the reduction in flood damages

resulting from adding flood control facilities.

2. FLOOD CONTROL HYDROLOGY

a. General

A study of the flood characteristics of the Deer Creek watershed

was made and used to develop 100-year frequency flood hydrographs for the pur-

pose of evaluating potential flood control facilities and the benefits there-

of. Two hydrographs were developed, both of which resulted in a 100-year peak

discharge at Glenrock. These hydrographs were developed based on the May 1965

flood flows as measured at the Glenrock gage and estimates of the contributing

11-2

rainfall depths and distribution. One of these events was the result of heavy

rainfall in the area below the dam site as actually occurred during the 1965

flood. The second event consists of a hypothetical flood having a 1 aD-year

peak discharge at the proposed dam site. Both floods produce an approximate

100-year peak flow of 12,800 cfs at Glenrock (see Fig. 1 of the Interim

Report) •

In developing these floods, the U.S. Army Corps of Engineers'

(Corps') HEC-1 computer program, in conjunction with other recognized hydro-

logic procedures, was used to simulate the rainfall-runoff process and to per-

form reservoir and river routing of flood hydrographs.

b. Proc edures

In developing hydrographs, the Deer Creek watershed was divided

into eight subbasins. The subbasins are as shown in Fig. 2. Three of the

subbasins are located upstream of the dam site and five are located downstream

of the dam site. In general, the subbasins were selected so that each in-

cluded a major tributary of Deer Creek. However, because the shape of the

drainage basin below the dam site is long and narrow, this part was divided

into three separate subbasins to more accurately reflect the rainfall-runoff

characteristics of the area.

Synthetic unit hydrographs (Fig. 2) were developed for each sub-

basin in the Deer Creek watershed using a modified version of the Clark syn-

thetic unit hydrograph method. The time of concentration (Tc) (which is the

time lapse between the occurrence of the peak rainfall and the peak runoff)

was estimated for each subbasin using the Kirpich formula and a time-area

curve was developed. The values of Tc obtained using the Kirpich formula

agree with estimates of mean channel travel time for conditions of bank-full

discharge. In the Clark method, the attenuating effects of Basin storage on

flood-wave propagation are accounted for by routing the time-area curve

through a linear reservoir having the same storage characteristics as the

Basin. The modified Clark method uses Muskingum routing rather than a linear

11-3

reservoir to account for the effects of Basin storage. Use of the Muskingum

routing equation requires that two parameters, X and K, be determined. The

Muskingum X parameter accounts for the effect of inflow on channel storage and

is typically equal to 0.2 for natural channels. The storage coefficient, K,

is a measure of the mean travel time through a specific channel reach and has

the dimension of time. The storage coefficient for each subbasin was assumed

to be equal to the Tc for that Basin.

c. lOa-Year Peak Flood at Glenrock

The storm which occurred May 13-15, 1965 produced heavy precipi ta-

tion which combined with snowmelt to yield a flood wave having an instantane-

ous peak discharge at Glenrock approximately equal to the 100-year peak dis-

charge. The areal and time distributions of rainfall in the Deer Creek Basin

(Basin) due to this storm were estimated based on precipitation estimates for

this storm made by the U.S. Bureau of Reclamation (USBR) and U.S. Geological

Survey (USGS). Utilizing these distributions, the hyetograph for each sub-

basin was estimated and used with the HEC-1 computer program to simulate the

rainfall-runoff process for the May 1965 storm and flood. Input to HEC-1 con-

sisted of the synthetic unit hydrographs, the estimated hyetographs and the

loss rate and snowpack data. The snowmelt was simulated using the energy-

budget method. During the storm the temperature was assumed to be 500 F at

Glenrock (El 5000), wind speed was assumed to be negligible, insolation was

assumed to be 61 langley /hr and the temperature lapse rate was assumed to be

30 F per 1, OOO-foot increase in elevation. The Basin ranges in elevation

from 5000 feet above mean sea level near the mouth at Glenrock to 9000 feet at

its headwaters. It was assumed that snowpack lying between 6000 feet and

9000 feet had an average moisture content of 20 inches. The loss rate was

assumed to be 0.12 inch/hour.

Shown in Fig. 3 are the observed May 1965 flood hydrograph at Glen-

rock, the simulated flood hydrograph at Glenrock, and the simulated upstream

and downstream flood hydrographs at Glenrock. As can be seen, the peak

1I-4

discharge at Glenrock was primarily due to runoff from the area below the pro-

posed dam site. Based on the rainfall-runoff simulation, it is estimated that

approximately 85~ of the peak discharge at Glenrock was due to runoff from the

downstream area.

d. 100-Year Peak Flood at the Dam Site

A flood having a lOO-year peak discharge at the proposed dam site

was selected as the basis for sizing potential flood control facilities and

for estimating benefits. The 100-year peak discharge at the dam site was

estimated based on reducing the 100-year peak discharge at Glenrock by the

square root (Chow Handbook of Hydrology) of the ratio of the drainage area

upstream of the dam site (134 square miles) to the drainage area of Deer Creek

at Glenrock (212 square miles). Experience has shown this is a reliable

method for approximating peak flows. The hydrograph for this flood and the

contribution from the drainage area below the dam site were estimated using

the synthetic unit hydrographs described above and adjusting the rainfall pat-

terns slightly so that the 100-year peak was obtained at both the dam site and

at Glenrock. The upstream and downstream components of this flood and the

total flood at Glenrock are shown in Fig. 3.

3. PRELIMINARY DESIGN OF FLOOD CONTROL FACILITIES

A Project layout which includes flood control facilities sized for

the 100-year flood at the dam site was developed. The layout is based on

selection of a rockfill dam with a concrete membrane (face) similar to that

described in Section VII, except that the height of the dam and spillway are

modified for flood control. The normal reservoir water level remains at

EI 6700. The dam crest is raised 6 feet (EI 6706) to provide about

6,000 ac-ft of flood control storage. A two-level non-gated overflow spillway

weir is provided in the excavated spillway channel through the ridge on the

right side of the dam. The purpose of the two-level weir is to reduce peak

outflow of floods up to the 100-year frequency by storing a portion of their

11-5

volume. One section of the spillway weir, 20 feet wide, is set at the normal

reservoir level and will pass all inflow up to and including the 100- year

flood without exceeding the 6 feet of flood control storage. The other sec-

tion, 140 feet wide, is set 6 feet higher (EI 6706) and will operate when the

reservoir inflow exceeds that of the 100-year flood.

The effects of these facilities on the peak flow at the dam and at

Glenrock were determined and are compared in Table 11-1 to the natural flow

(without a project) and to the flow for the Project without specific flood

control facilities. The spillway for the Project without specific flood con-

trol facilities consists of a 170-foot-wide excavated channel through the

ridge near the right abutment of the dam, with a low non-gated weir set at the

maximum water supply storage level (EI 6700). This spillway will pass flood

flows of all magnitudes, up to and including the estimated PMF outflow of

49,000 cfs.

From Table 11-1, it can be seen that for the Project with a flood

control spillway as described above, the 100-year peak flow at Glenrock would

be an estimated 7,500 cfs. This discharge may be compared to 7,900 cfs for a

project without specific flood control facilities and the natural flow of

12,800 cfs (without a project).

The effect that the flood control facilities would have on the his-

torical 1965 flood was also analyzed. The analysis which is summarized in

Table 11-2 indicates that flood control facilities at the dam would not have

reduced the peak of this flood significantly at Glenrock, because as discussed

previously, the major area of flood-producing runoff was in this case located

downstream of the proposed Project.

A comparison of Tables 11-1 and 11-2 indicates that with flood con-

trol facilities, the Project could reduce the 100-year flood peak at Glenrock

between 20% and 40% depending on which part of the drainage area contributed

to the maximum runoff. In the case where no specific flood control facilities

are provided, the Project will reduce the flood peak at Glenrock by 15% to

II-6

40%, depending on where the larger portion of the runoff contributing to the

peak originates.

The hydrograph of outflow from the reservoir for both the 100-year

and the 1965 floods with and without flood control facilities is shown in

Fig. 3.

4. COST OF FLOOD CONTROL FEATURES

The investment cost of the flood control features was estimated

based on the difference in cost of a project without these features and the

cost of a project with them. The Total Investment Cost for the flood control

features based on this difference is $1,325,000. The estimated corresponding

annual cost for these features based on an interest rate of 10~ and a 30-year

repayment period and assuming the flood control facilities will not increase

the Project's operation and maintenance cost is $140,000.

5. ECONOMICS OF FLOOD CONTROL

The primary benefits for adding flood control facilities are the

reduction in the average annual damages made possible by these fac!li ties,

less the reduction which would have occurred if flood control facilities were

not included in the Project. Based on the damage-frequency curve from Fig. 8

of the Interim Report the following annual damage reductions are derived:

Reduction in flood damages made possible by the flood control facilities •••••••••••••••••

Reduction which would occur without flood control facilities •••••.••••••••••••••••••••••••

Benefits attributed to flood control facilities •••

$40,000 per year

25,000 per year

$15,000 per year

1I-7

Comparison of the benefits with the costs indicates a benefit/cost

ratio of 0.1. The above analysis indicates that it is not economical to

include specific flood control facilities as a part of the Project. As indi-

cated above, however, the Project without flood control facilities will pro-

vide incidental flood control benefits of an estimated average of $25,000 per

year. These incidental benefits will be included in the overall Project

economic study summarized in Section IX.

Design Condition

No Project •••••••••

with flood control facilities •••••••

No flood control facilities •••••••

TABLE 11-1

DEER CREEK PROJECT

FLOOD CONTROL CAPABILITIES FOR 100-YEAR FLOOD

Flood Control Outlet

20' wide spillway Crest set at El 6700

Spillway

170' wide spillway Crest set at El 6706

170' wide spillway Crest set at E1 6700

Reservoir Peak Inflow

(cf,)

10,000

10,000

Peak Flow Maximum at

Peak Outflow R~servoir Glenrock (cf,) Elevation (cfs)

12,800

1,300 6706 7,SOO

2,700 6703 7,900

Design Condition

No Project •••••••••

With flood control facilities •••••••

No flood control facilities •••••••

TABLE 11-2

DEER CREEK PROJECT

FLOOD CONTROL CAPABILITIES FOR IIISTORICAL FLOOD OF MAY 1965

Reservoir Peak Inflow

Flood Control Outlet Spillway (cfs)

20' wide spillway 170' wide spillway 9,100 Crest set at El 6700 Crest set at El 6706

170' wide spillway 9,100 Crest set at El 6700

Peak Flow Maximum at

Pea k Outf low Reservoir Glenrock (cfs) Elevation (cfs)

12,800

400 6704 10,500

2,300 6703 10,600

SECTION III

RESERVOIR OPERATION STUDIES

1. INTRODUCTION

Studies described in this section are based on the assumption that

all flows at the Project site in excess of water rights requirements in the

Deer Creek Basin are storable and therefore will contribute to the Project

yield. Water rights requirements in the North Platte Basin below the conflu-

ence with Deer Creek and their effect on the Project's storable flow and yield

are assessed preliminarily in the next section.

To estimate the firm yield of municipal and industrial water that

would be developed by the proposed Deer Creek Reservoir, a series of reservoir

operation studies was made using historical flow data for the period 1936 to

1980 and computer modeling techniques. In developing the models, it was first

necessary to determine the volume of water on a monthly basis which legally

can be stored in the reservoir. As presented in this section, the volume is

equal to the natural flow in Deer Creek at the dam site less the irrigation

water, when available, needed to satisfy permitted water rights. In the case

of Deer Creek, however, the use of this procedure is difficult because the

only long-term stream gage records are at Glenrock and these records reflect

flows after most of the irrigation diversions have been made. Also, there are

no accurate records of actual diversions and return flows. It is necessary,

therefore, to estimate the amount of water which has been diverted historical-

ly and calculate the resulting pattern of return flows in order to develop an

approximate virgin flow record. Once the virgin flow record at Glenrock had

been estimated, the estimated local inflow between Glenrock and the reservoir

site is subtracted to obtain the estimated virgin flow record at the reservoir

site. The storable flow is then estimated by following the procedure sum-

marized above.

III-2

The actual mechanics of estimating the virgin flow record and the

storable flow record at the reservoir site were performed by using two sep-

arate computer programs. In addition, a third computer program was developed

to simulate the actual month-by-month operation of the reservoir. The actual

operations performed by each program are summarized below.

2. VIRGIN FLOW RECORD

The critical step in determining the virgin flow record at Glenrock

is establishing the historic pattern of irrigation diversions. It is esti-

mated that only about 3,400 acres of the 6,209 acres having permitted water

rights on the main stem of Deer Creek are currently being irrigated. When

flow is available in Deer Creek during the growing season, diversion of irri-

gation waters is made at a rate of 2 cfs/70 acres for pre-1945 water rights.

While the length of the irrigation period actually depends on the availability

of water in the latter months of the growing season, it was assumed that irri-

gation took place during the months of April through October in order to

reduce the complexity of the computer model.

The flow in Deer Creek during the months of April, May, and June

accounts for approximately 80% of the mean annual flow. Therefore, during

these months it was assumed that the lesser of 2 cfs/70 acres or the available

flow was historically diverted. During the months of July through October,

the flow in Deer Creek is usually too low to allow all holders of water rights

to divert irrigation waters at the maximum rate of 2 cfs/70 acres. Most of

the flow recorded at Glenrock for these months is probably subsurface return

flow from diversions made during the spring runoff period. In addition, the

percentage of diverted water used consumptively during July through October is

very high. These last two facts make it difficult to accurately estimate the

virgin flow or the volume of water actually diverted during this period. For

the estimates herein, it was assumed that the volume of water available for

diversion was twice the amount shown in the gage record at Glenrock. The

actual amount of water diverted was assumed to be equal to the lesser of

111-3

2 cfs/70 acres or twice the gage record. This methodology is conservative in

that it prevents overestimation of the storable flow.

After the historical diversions were determined, it was necessary

to estimate the portion used consumptively and the volume and pattern of irri-

gation return flows. The determination of consumptive use was based on esti-

mates of the potential crop evapotranspiration for the Deer Creek farmlands.

The potential crop evapotranspiration (PET) depends, among other things, on

the amount of precipitation which falls during the growing season. Therefore,

the monthly PET was estimated for wet, dry, and average runoff conditions.

Based on an analysis of Deer Creek flow records, it was decided that if the

mean annual flow was less than 20, 000 ac-ft, the year would be classified as

"dry," greater than 70,000 ac-ft "wet," and "average" otherwise.

The volume of water which must be diverted to meet the crop-

irrigation requirement must include water which will be lost in conveyance to

the farm and losses of water on the fields from deep percolation and surface

runoff. The conveyance losses which include seepage from the ditch, opera-

tional waste, and evaporation, were estimated to be equal to 20~ of the water

diverted. The volume of water lost to deep percolation and surface runoff was

estimated to be 50~ of the volume applied to the field. Therefore, the farmer

must divert a volume of water 2.5 times the crop-irrigation requirement.

Frequently the farmer may divert an amount of water greater than or

less than the actual farm-delivery requirement. A measure of the amount

actually diverted is the irrigation application ratio (IAR) - the ratio of the

amount of water diverted to the required diversion. The fraction of water

used consumptively, the fraction of water returning as surface runoff, and the

fraction of water returning to the stream via the groundwater system as func-

tions of the IAR were estimated. In addition, the time distribution of sub-

surface return flows to the stream was estimated using the Glover equation for

depletion of a stream due to pumping of a well. Using this information, the

historical return flow pattern was estimated.

III-4

The virgin flow record at Glenrock was calculated by subtracting

the estimated return flow due to all previous diversion from the gage record

and adding to this quantity the estimated historic diversions. To obtain the

virgin flow record at the dam site the estimated local inflow between the dam

site and Glenrock was subtracted from the virgin flow record at Glenrock.

The estimated local inflow entering Deer Creek below the dam site

probably includes surface and groundwater return flows due to diversions from

the downstream tributaries as well as natural tributary and groundwater in-

flow. It was assumed that no appreciable local inflow occurs during the

months of July, August, September, and October. During the non-irrigation

months of November through March, it was assumed that all recorded flow in

excess of the return flows from diversions on the main stem of Deer Creek was

base flow. This base flow quantity was multiplied by the drainage area ratio

in order to determine local inflow for the non-irrigation months. Local in-

flow during the heavy runoff period from April through June was assumed to be

negligible except when the record flows are high. It was assumed that monthly

flows in the 80th percentile were the result of major flood-producing storms

which significantly affect local runoff. The volume of local runoff for April

through June was calculated by multiplying the volume of flow for the 80th

percentile flows in excess of the mean volume of those flows below the 80th

percentile by the drainage area ratio.

3. STORABLE FLOWS

The volume of flow which can be stored in the Deer Creek Reservoir

(ignoring the potential effects of North Platte River water rights, which are

discussed in Section IV) was determined for two scenarios. The first scenario

assumes that the present pattern of irrigation diversion continues. The

second scenario assumes that all 6,209 acres with direct flow rights on the

main stem of Deer Creek are irrigated. In both cases it is assumed that water

is diverted at a rate of 2 cfs/10 acres when flow is available in the stream.

111-5

Irrigated acreage upstream and downstream of the dam site and the maximum

diversion rate for each scenario are summarized below.

Location

Upstream Downstream

Total ••

Location

Upstream Downstream

Total ••

Scenario 1 (Historical Usage)

Irrigated Acreage (acres)

1,140 2,260

3,400

Maximum Diversion Rate

(cfs)

33 64

97

Scenario 2 (Maximum Legal Usage)

Irrigated Acreage (acres)

2,288 3,921

6,209

Maximum Diversion Rate

(cfs)

65 112

177

Based on the estimated virgin flow at the dam site, the upstream

diversion and return flow pattern, and consumptive use, the flows at the dam

site were estimated using the previously described information. It was

assumed that all return flows due to upstream diversions enter Deer Creek up-

stream of the reservoir. Physical inflow to the reservoir was estimated as

being equal to the virgin flow at the dam site less diversions, plus the

return flow occurring in that month due to all previous diversions. Down-

stream diversions were estimated to be equal to the lesser of the decreed

water rights or the physical inflow to the reservoir plus the local inflow.

The volume of water which must be released from the reservoir to meet the

downstream diversion requirements within the Basin was calculated as that

volume of water less than or equal to the physical inflow, which cannot be

III-6

satisfied by the local inflow and 50% of the return flow occurring the first

month. The factor of 50% accounts for the nonavailability of return flows to

some irrigation ditches due to their location. This factor of 50% was esti-

mated based on a study of the mapped irrigation diversion points and irrigated

acreage. The storable flow at the reservoir site is equal to the physical

inflow to the reservoir less the volume of water which must be released from

the reservoir to meet the downstream diversion requirements.

Table III-1, "Historical Monthly Flow Recorded by USGS at Glen-

rock," shows the historically measured flows of Deer Creek at Glenrock for the

period 1936-80. These flows reflect the historic irrigation consumptive use

and return flow patterns (Scenario 1). Table III-2, "Comparable Gage Record

at Glenrock, Scenario 2," shows the estimated gage record at Glenrock if all

6,209 acres with water rights had been irrigated at the decreed amount.

Tables III-3 through III-6 show the estimated physical inflow to the reservoir

and the storable flow at the reservoir for the two scenarios, respectively.

Detailed model output tables are shown in Appendix B.

4. WATER YIELD

The firm yield of municipal and industrial water that would be pro-

duced by the Project reservoir with 61,000 ac-ft of water supply storage

capaci ty was determined from the storable flow estimated for Scenarios 1 and

2. Operation of the reservoir was simulated using a model which basically

accounts for spillage and evaporation losses while making releases to meet a

specified annual demand pattern for municipal and industrial water. It was

assumed that during the months of December through March the reservoir would

be covered by ice and there would be essentially no evaporation. The firm

annual yields of the Project indicated by these studies for Scenarios 1 and 2

are approximately 20,000 and 16,000 ac-ft, respectively.

111-7

5. PROJECT EFFECTS ON THE NORTH PLATTE RIVER

The monthly flow at Glenrock based on the historical flow

(Table 111-1) less the firm yield and evaporation loss from each scenario is

summarized in Tables 111-7 and III-8, "New Flow into North Platte." Compar-

ison of these tables with Tables II1-1 and I11-2 indicates that the Project,

on an average annual basis, would reduce flows to the North Platte by approx-

imately 21,600 ac-ft/yr under historical irrigation conditions. For utiliza-

tion of all Deer Creek decreed rights, the flow reduction would be approx-

imately 17,300 ac-ft/yr. This depletion of North Platte flows is essentially

equal to the yield of the reservoir for the given scenario, plus evaporation

losses.

DEER CREEK PROJECT HISTORICAL. MONTHLY FLOW RECORDED BY USGS AT GLENROCK (AF)

(DEER CREEK BELOW MILLAR WASTEWAY, USGS GAGING STATION NO. 066465)

¥!:ARS OCT NOV DEC ~, AN '1!:B MAR APR MAY JUNE JULY AUG SEPT ANN. ........ ........ ........ -....... ........ ........ . ....... ........ ........ ........ ........ . ....... ........

193b 208 88~ 1020 756 635 932 515n 1850 94 6 4 0 11543 1937 137 701 57) 49~ 58) 9"u 11('190 12320 11?70 5160 154 191 43671 1938 57) , DB 0 1080 11 OU 968 1940 18750 14120 1490 283 31 420 41835 19.19 352 893 1050 922 778 1320 13740 8800 854 68 25 9 28811 1940 58 508 659 65U 6B2 660 6~30 10650 129 4 0 26 20556· 1941 289 444 519 6'28 561 918 10020 35790 3280 422 1"00 841 554)' 194~ 1750 238u 1'10 1320 1090 \260 21290 38100 4770 651 87 246 "4654 1943 1310 IblO 1550 1330 1220 5790 9740 ]080 2310 243 14 22 28219 1944 357 730 823 1060 1090 1260 10580 31920 5500 465 51 )9 53875 1945 199 1050 793 925 ln70 1420 5540 35580 10010 1270 260 465 59202 194~ 1450 1470 1250 1270 1110 3730 9320 22850 9060 629 106 634 !§:l879 1947 1650 175(J 1330 1020 1060 3600 13700 13610 11130 3730 26 15 53211 1949 403 1280 1510 1~60 1420 1490 8180 1!'110 1160 153 41 31 27]38 1949 237 98, 1440 143(J 1200 20'0 9870 18390 )890 164 9 '79 39761 1950 866 1230 1010 942 1160 1290 8770 12000 46!)0 407 15 141 ]2481 1951 837 S030 968 9()0 AO! 898 4390 11980 2150 499 128 '71 24646 1952 101 599 592 930 911 1190 9700 190('10 4650 1]9 18 17 38047 1953 14 269 711 855 740 1160 3490 19340 3170 12 2' 1 10016 19~4 39 53:2 771 829 '-73 1400 1094/) 5240 439 16 8 3 21090 1955 59 til 0 654 b49 567 812 8340 7700 4940 240 19 4 24614 1956 68 303 626 593 626 2130 612 322 416 7 6 2 5'711 1957 9 326 768 8le 867 1130 3670 15630 5220 511 16 26 29011 1958 398 a16 840 9S0 1230 2140 10010 14990 186 57 :ao 5 31602 1959 34 366 63l 559 530 728 5700 7350 8 t 20 0 0 16001 1960 26 133 833 845 708 5220 10340 50~0 26 19 0 0 23200 1961 12 28 26 2. 843 1190 2950 4980 433 98 59 180 101:U 196~ 554 661 641 937 2020 1520 21180 13010 4'720 217 !5 215 45680 1963 506 l07 568 996 1100 3100 31UO 5020 6040 107 2 24. 21094 1964 195 181 658 826 '91 873 3500 43280 118~0 '725 :aa ]2 6:2919 1965 142 810 1030 860 83n 954 8220 311910 4290 285 6. 561 8696'7 '966 12iO 964 932 1300 1200 259u 7630 9210 312 :'1 32 ]0 2551] 1967 172 954 10ao 1130 992 5560 8190 12770 7690 3720 91 217 42166 1968 736 1170 944 1060 1230 1650 9080 34600 10660 555 126 10l 61914 1969 684 825 821 1140 1060 1290 8450 6680 40'70 55l 44 21 25614 1970 )16 1190 1370 1320 10&0 14~0 3910 59820 )1470 '765 112 192 103055 19'71 990 1360 1440 1640 1440 2780 14100 49670 12320 108 29 901 8671. 197:2 1845 2045 202~ 1448 1589 7377 9160 19668 3371 349 259 298 494]4 19'7) 2087 1692 1460 1656 1 ~ l' \81l 4421 84539 17274 ll00 891 1'10 120506 1974 1082 2132 2277 2130 1958 4921 '153'7 275)9 2340 123 120 509 66661 1975 ~O87 1662 1422 1222 986 1962 6075 25087 7650 715 60 24l 49171 H 1~76 17~l 118b 1345 l:UO 1250 1628 8942 21408 )386 422 89 547 43186 5; 19'77 644 1216 1188 1139 893 1198 t7667 10759 256 27 54 70 35111 t-4 1978 1176 1166 1297 156) 1305 2041 5324 29872 2622 16 88 lOa 46'74(') tr:1 1979 634 1194 1222 1219 1226 1450 4955 640J 845 47 131 1'77 19565 H H 1980 541 1087 1180 121b 1!39 1301 12841 15061 991 26 (\ 14 15799 H .........•................................................................................................ I

~ 666 914 10)'7 1054 1052 :a047 9129 19867 49H4 565 112 220 41701

DEER CREEK PROJECT CO"'PARABLE GAGr!: PECORD AT GLEI~POCI< CAr)

Scenario 2

i'~ARS OCT ~'OV DEC JAN rEB IAAR APR MAY JUNI': JULY AUG S!:PT ANN. ......... ........ . ........ .......... -.. -.- .. . .... -... . ......... . ....... ........ . .... _-. . ....... . ....... ........

1936 208 S8S 1020 7~6 635 932 3748 1073 16 11 9 12 9308 1917 349 793 6~5 561 647 952 9913 Q901 8483 2420 111 207 3505) 1938 574 1627 1525 14'75 1293 2229 18779 11633 829 49 23 120 40158 19 J 9 2Ui 11 1 2 1229 tOi9 910 1440 t3627 61R7 361 25 16 \ 8 26211 1940 28 686 805 782 792 763 6010 8048 33 1 7 9 1 '2 1798'7 194 1 14) b10 6~7 753 670 1034 9850 33157 2132 '78 65\ lS5 50092 194:2 1481 271U 1979 1546 1280 1428 21221 35523 3199 160 42 68 70639 1943 11 2 B 191 8 1804 1547 1406 5955 9601 1926 1120 31 20 20 26677 1944 177 852 923 1144 1162 1322 10422 2929!5 3659 lno 39 39 49134 19 4 ~ 626 1358 1047 1143 1259 15 e 7 5075 33027 7762 453 57 114 535&9 19.6 1) 1 2 1851 1564 1536 1342 3934 9150 20306 6791 164 46 ~57 48254 1947 1468 2131 1643 \284 1290 )800 13662 11 0 ~ 7 9454 ISS1 82 103 478:24 1948 3bO 1 744 1885 , e 7 e 1694 1734 7906 7611 S86 31 20 21 ~~471 1949 122 1186 1609 1580 1326 2185 9696 15774 2537 43 32 12 ]61~3 19~O 6~'7 149) 1227 1130 1321 1434 8464 9418 3098 82 37 38 28398 1951 646 13' 5 1204 110 J gel 1044 3959 9412 1308 96 )0 30 21127 1952 1 '7 2 824 777 \093 1048 1 315 9~06 16393 3(190 46 34 34 34332 19!5 ) 66 ~54 965 1058 915 1315 3136 16767 2l01i 42 31 31 27089 19 ~H 59 787 981 101 :2 1029 1540 10844 3376 125 15 9 11 19787 19 5 ~ 17 727 751 737 640 900 7911') 5080 3302 48 35 35 20180 1 956 69 5R6 860 795 801 2285 613 60 89 1 1 1 6161 1 9!5 '7 1 349 1ee 855 883 1143 3188 12994 3473 112 J8 38 23864 195 B 280 1121 1091 1126 141 7 2306 9918 12411 47 18 10 13 2975' 1

DEER CREEK PROJECT PHYSICAL INfLUW TO tHE ~~SERVOIR (AP')

Scenario 1

'tEARS OCT NOV ore JAN FFS MAR APR MAY JtJNE JULy AUC SEPt ANN, ..... -.. . -.. -.-. ........ -....... ......... ......... ........ ........ ........ .... -._- ........ . ....... ........

193b 208 577 663 491 41) 60b 6582 30t2 6 5 4 4 12572 1937 15 1 431 348 298 159 568 10759 14284 10Q24 '7636 22 41 458;n 19) 8 S7!5 557 582 b10 536 1176 15246 16150 2329 43 9 275 ]8087 1939 4JO 593 687 596 502 852 11849 10931 CJ71 11 8 8 27439 194u 15 330 427 41(; 440 422 6680 12795 6 3 2 2 21539 1941 323 269 320 388 352 592 10163 3(1972 5153 90 2'732 859 52213 1942 22~6 1454 1027 789 646 767 17041 32507 6597 261 15 66 63427 1943 1851 961 931 802 737 3718 9812 5165 3793 14 8 8 27800 t944 384 429 495 b50 673 78b 10684 28233 7372 118 11 13 49847 1945 l1b4 5gb 439 ~37 638 875 5618 307'75 9660 1545 '4 272 52142 1946 2007 870 '734 762 664 2377 9379 24922 8965 246 14 583 51524 1947 2282 1072 801 612 641 2301 t 1762 15695 10845 6207 19 23 !52~6t 1948 335 719 887 928 847 897 8218 121!56 1635 10 8 8 2b648 1949 230 634 931 918 772 1335 10009 20526 5766 10 8 8 41146 1950 1258 689 562 534 685 779 8A4! 14082 6503 79 10 11 34031 19'5 1 1212 567 541 512 458 522 4461 14063 3552 156 11 14 26070 1952 100 367 363 580 569 753 9A13 21117 6526 10 8 8 40413 1953 15 118 426 508 437 715 3591'\ 21447 5248 10 '7 7 )~528 1954 15 289 451 491 523 871 11040 '7348 256 7 5 5 21100 1955 10 386 415 40., 359 529 8491 9845 6915 12 7 7 27286 1956 15 13~ 351 333 l59 1342 661 206 :166 5 ] 3 3777 1957 6 256 535 5'7t» 591 759 )867 17778 7095 15l 11 13 31638 1958 455 490 509 555 '764 1360 10108 17096 27 4 3 3 31373 1959 4 ~ 11 388 339 325 453 5845 9491 6 1 2 2 1'7068 1960 3 57 516 ~23 439 3372 10485 7190 6 3 2 2 22591 1961 3 50 42 40 528 753 3096 7121 247 6 5 51 11944 1962 862 413 401 592 1]01 974 17065 15145 6585 10 8 41 43396 1963 626 160 312 594 666 1972 3U6 7115 7906 10 8 65 22621 1964 100 146 383 494 474 531 3598 36181 t0951 l51 15 19 53242 1965 49 S02 644 532 513 598 8327 33131 6172 24 8 451 50952 t966 1806 541 52'7 780 721 1b34 7698 11291 108 6 5 4 25122 1967 490 610 693 720 635 3602 8436 14911 8035 6213 18 24 44385 1968 870 607 487 580 705 986 9098 30029 10056 183 12 15 53629 1969 964 465 471 686 640 797 8532 8743 5932 181 12 15 27439 1970 310 741 8~9 826 671 941 4031 47763 24687 396 16 36 111277 1971 1433 805 866 1008 884 1765 t2046 40637 11261 10 8 1077 71799 197~ 2408 1242 1237 875 973 4745 9225 21746 5219 47 26 97 47841 1971 2652 1006 866 1007 93'7 1139 4490 65039 14724 1618 662 2991 97131 H 1974 1421 t27!S 1390 1310 1209 3145 1720'7 29581 3812 13 9 165 60737 > 1975 2695 1016 864 743 595 1236 6160 2'718:2 7992 334 16 66 48899 OJ ~ 1976 :2368 688 800 739 '758 1014 9015 23494 5240 87 10 411 44624 t11 1971 90B 145 72' 699 541 745 14552 12855 67 6 4 4 3185) H 1978 1766 684 779 964 80'7 12QO 5440 31988 4311 -10 8 39 48085 H 1979 81:16 701 729 774 745 898 5041 8498 934 10 11 49 19276 H I 1980 834 699 758 1'79 993 836 11'28 17196 1285 10 8 8 346]6 VJ ..............................................................................•........•........•..•...•..

866 581 626 642 645 1296 8631 19721 5466 582 85 179 )9321

DEER CREEK PROJECT PHYSICAL INFLOw TO THE R[SERVOlk CAr)

Scenario 2

'tEARS OCT NOV OEC JAN rEB MAR APR MAY JUNE JULY AUG SEPT ANN, ........ ......•. ........ ........ ........ ........ ......... ........ ........ ........ ........ • ••••••• . .......

1936 208 577 663 491 413 60b ~844 2096 13 10 8 9 10939 1937 234 501 409 3~2 4Cl6 tll0 J0324 13294 9785 6391 43 80 42429 1938 ~37 772 757 757 6b4 12QO 15238 15135 1511 44 16 190 36912 1939 344 710 785 680 ~76 916 1180 t q878 (0) 15 11 11 26)30 1940 19 395 481 466 482 462 6609 11723 12 6 ] 4 20664 1941 21~ 329 370 433 389 627 10087 29897 4212 78 1451 611 48'704 1942 2174 1692 1220 947 782 883 17043 31495 5699 196 22 60 62213 1943 lb07 111 3 1()~9 907 928 3796 9777 4122 2865 24 16 16 26128 1944 30B !H9 595 736 749 8~2 10638 27182 6436 99 18 19 48181 194~ 896 7!51 ~69 644 731 ~54 ~58) 29732 87)3 70) 36 214 4954'7 1946 1&30 1065 894 895 779 24Hi 9362 23898 8052 182 21 J61 49816 \941 2061 1219 923 713 730 2378 11725 146!51 9916 4964 36 46 49361 194& 326 913 1045 1063 961 1002 820!5 11136 1029 17 1 ] 13 2~724 1949 168 725 1007 986 830 1387 9950 19464 4827 20 15 15 ]9)92 1950 978 849 696 643 780 860 8808 1]041 5578 '2 17 18 32341 1951 937 726 674 620 !55) 603 4428 13022 2627 126 19 21 24354 195~ 235 482 459 663 643 817 9766 20064 5589 20 15 15 38768 1953 29 227 516 588 !S08 777 3515 20395 4310 19 14 14 ]0913 1954 29 398 542 !)'71 594 933 lu991 6293 176 10 6 7 20!551 1955 12 437 458 449 393 !561 8412 8768 5812 21 14 14 25411 1956 ~9 241 441 412 429 1404 665 1\9 200 :2 2 2 1946 1957 3 ~!50 531 5'73 589 756 3762 16695 6148 120 17 19 29464 1958 ]67 610 609 641 840 1426 10062 16044 29 7 4 5 ]0645 1959 '7 262 431 379 358 485 5761 8413 12 b ! 4 16126 1960 6 101 !55A 56] 472 340] 10406 6113 12 6 ] 4 2165) 1961 6 101 84 80 561 784 2920 60!50 171 10 6 38 10810 196:2 613 501 474 654 1352 1020 16997 14077 5651 20 15 42 41415 1963 !SO! 288 418 6R5 746 2041 3060 6071 6977 20 15 60 20888 1964 95 256 476 575 546 59! 3!525 35129 10013 244 21 24 51500 1965 57 609 734 6 t 1 583 Q!9 8277 32076 5233 31 15 291 49175 1966 1564 701 660 8S9 816 1715 7666 102!50 87 10 6 7 24]71 1967 351 678 '7~0 1'71 676 3640 8362 13838 7096 4962 34 45 41203 1968 737 824 664 728 832 1100 9092 29015 91!51 143 19 21 5~324 1969 741 611 593 787 728 872 8495 7698 ~OO] 141 19 21 25710 1970 242 8S5 955 909 744 1005 3984 46710 23750 271 22 17 79485 1971 1161 966 1000 '118 979 1846 12013 39596 10336 20 16 6'73 69'724 1972 2226 t409 1372 999 1071 4829 9195 2070& 4296 49 29 81 46253 1973 2436 1113 973 1098 101'7 1208 4441 63989 13790 730 415 2160 93396 1974 130& 1583 1631 1507 1374 3289 1722' 28592 2928 25 18 248 59728 1975 ,491 1149 973 837 677 1307 6119 26134 7059 235 22 60 47061 H t976 2145 825 915 835 842 1087 8975 22446 4309 77 1'7 271 42744 ~ 19'77 70) 892 849 801 630 821 14516 11 8 1 1 60 9 6 6 31104 L' \978 1445 791 8b8 1036 866 1342 5179 30925 3382 20 15 41 46111 ~ 1979 682 845 849 97. 833 973 5001 7453 ~87 15 14 39 18165 H 1980 604 796 840 848 105t 887 11167 16133 779 16 12 12 3114!5 H

H ...........................................•..........................................•.•.......•..•...... I 748 70S 728 7'9 720 1362 8560 18697 4776 449 51 1]~ 37663 .p..

DEER CREEK PROJECT STORABLE fLUW AT T~E RESERVOIR tAr)

Scenario 1

'tEARS (JCT NOV DEC JMJ fEB MAR APR MAY JUNr. JULy AUG SEPT ANN,

........ ........ ......... ---_ .... -..... --- .... -... . ....... --.-.... ........ ... _--.- . ....... . ....... . ....... 193b 208 577 663 491 413 60b 3CJ66 67B 2 1 1 1 7606 1937 151 431 349 298 359 568 9('30 11342 9199 4435 '7 13 36181 193B 122 5~7 592 6'0 536 1176 15106 13179 388 3 2 1~ 32272 1939 59 593 fIIS7 596 502 852 10917 7921 85 1 1 1 ~2216 1940 2 JlO 427 416 440 422 4718 9770 2 1 0 0 16528 1941 30 269 320 388 l!S2 592 8197 30972 2320 5 296 85 43826 1942 830 1454 1027 789 646 767 17041 32507 3802 12 3 4 58881 1943 570 961 931 S02 737 3718 7885 2167 CJ72 3 2 2 18751 \94' 51 429 495 b50 671 78b 8745 28124 4542 b 2 1 44505 1945 291 596 439 537 638 8'75 3686 30775 7950 11 3 4 17 45921 1946 655 87() 734 762 664 2377 7463 21937 7123 10 1 40 42640 1947 '791 1072 801 612 641 2301 10844 12702 9397 3011 6 '7 42184 1948 59 719 88'7 928 947 897 6310 91'79 209 2 1 1 20039 1949 22 634 931 918 772 1335 80~~ 17507 ~93] 3 2 2 33114 1950 3~4 b89 562 S34 685 779 6909 11 081 )679 5 ., 1 2S:2~1 1951 308 567 541 512 458 522 2530 11062 802 7 2 3 17114 1952 37 367 363 580 569 753 7973 1811 0 3697 l 2 2 32355 1953 4 116 426 S08 437 715 1715 18437 2415 3 2 2 24'78\ 19!54 4 289 451 491 523 ij71 9097 4337 12 1 0 1 16076 \955 1 386 415 408 359 529 6522 6815 3980 3 2 ~ 194:24 1956 4 132 351 333 159 1342 272 5 11 0 (') 0 2809 1957 0 2!56 ~35 5'76 591 759 1879 14747 4259 7 2 1 23613 1958 66 490 509 555 764 1360 8170 14090 ] 1 0 1 26009 1959 1 211 388 139 325 453 3875 6459 2 1 0 0 1~054 1960 1 57 516 523 439 33'72 eS15 4159 2 1 0 0 17584 1961 1 50 42 40 !528 753 1421 4093 11 1 0 2 6941 196~ 167 413 401 59~ 1301 974 17065 12123 3'758 3 2 1 36801 1963 108 160 312 594 666 19'72 1489 4113 5081 3 2 4 14505 1964 11 146 383 494 474 531 1'720 ]6181 9506 14 2 3 49465 1965 '7 502 644 532 513 598 6386 33131 3341 1 2 2., 45687 1966 554 541 527 790 721 1634 5772 8295 6 1 1 1 18832 1967 61 610 693 720 635 3602 6472 11885 5968 3007 6 '7 ]3663 1968 :U8 607 487 580 '05 986 7195 30029 8463 8 2 1 49283 1969 ':22 465 471 686 640 797 6600 5741 3108 8 2 3 18744 1970 ]9 741 859 826 671 941 2091 4'7763 2468'7 16 ] 3 '78641 1971 395 805 866 1008 884 1765 11183 40637 9898 1 2 103 67549 197~ 970 1242 123' 875 973 4745 7304 18755 2404 5 3 5 3841'

1-3 1973 9b8 1006 8b6 1007 93'7 1139 2559 65039 14101 122 3' 639 88417 :> 1974 450 12'75 1390 1310 1209 3145 17207 26624 1024 4 3 20 53662 td 1975 997 1016 864 7.3 595 1236 4231 24183 5928 13 1 4 39813 ~ trj !976 830 698 800 739 '758 1014 7087 20495 2419 6 2 24 ]4863

H 1977 209 745 727 699 541 '745 14223 9856 4 1 0 1 2'7'749 H 1978 506 684 779 964 807 1290 3484 ~8968 148'7 3 2 1 389'77 H 1979 196 701 729 774 '745 898 3107 !495 80 1 1 2 12'729

i

1980 162 699 758 779 993 a36 10152 1417B 136 ~ 1 1 28698 U1

..................................................................................................•.•..... 25'7 581 626 642 645 1296 7024 17459 3'760 241 9 24 32564

DEER CREEK PROJECT STORABLE fLOW At THE RESERVOIR CAr)

Scenario 2

'tEARS UCT NOV OEC JA~! fEB MAR APH MAY JUNE JUL't AUG SEPT ANN. ........ ........ ......... ........ ...... -- ........ --...... ........ ........ ........ ........ . ....... ........

1936 208 577 663 491 413 606 1'710 234 1 1 1 1 4906 1937 234 5('11 409 352 406 b10 6827 8160 5808 843 12 24 24187 1938 99 772 75'7 757 664 1290 13678 9944 130 3 1 6 2810] 1939 29 710 785 b80 576 91b 9396 4601 31 2 1 1 1772'7 1940 2 395 481 46b 48'2 462 3180 6435 3 1 1 1 11911 1941 13 329 370 433 389 627 6655 28085 717 6 70 34 377;J6 1942 574 1692 1220 947 782 8133 15825 30087 1240 11 4 5 53272 194.3 363 1113 1059 907 828 3796 6404 647 151 2 2 2 15473 1944 24 549 595 736 '749 852 7220 24808 148q 8 4 4 37038 1945 140 751 569 644 731 954 2619 27938 4913 28 5 11 3930] 1946 448 1065 894 895 '779 2478 5999 18b64 4094 10 4 17 35341 1947 526 1219 923 713 731') 2318 9366 9416 635B 554 10 10 32202 1948 51 913 1045 106] 963 1002 4963 5926 71 2 , 1 1590] 1949 11 725 1007 9E16 830 1387 6525 14180 930 4 3 ] 26591 1950 155 849 696 643 780 860 5423 7789 1192 7 3 4 18401 1951 148 7'26 674 620 !i5] 603 1993 7780 314 6 2 3 13421 195~ 19 482 459 663 64] 817 6356 14793 1193 5 3 4 25438 1953 6 227 516 sea 508 777 152A 1514] 752 4 ] 3 30055 1954 6 3gB 542 571 594 933 7592 1384 8 1 1 1 l~Oll '95' 2 437 458 449 193 561 4977 3477 1288 5 3 4 12053 1956 7 241 441 412 429 1404 248 2 ] 0 0 0 3186 1957 0 250 531 573 589 756 1611 11410 1388 8 4 4 17124 1958 41 610 609 641 840 1426 6678 10791 4 1 1 1 21643 1959 2 262 431 379 358 4~5 2690 3126 4 1 1 1 7738 1960 :2 107 5se 563 472 3403 6972 1311 3 1 1 1 1l39J 1961 1 101 B4 80 561 784 1222 1291 8 1 1 1 4135 1962 61 501 474 6~4 1352 10'0 15695 8792 1214 5 3 5 29776 1963 60 288 419 685 '746 ~041 1312 , 312 2026 5 3 5 8902 1964 11 256 476 57!5 546 595 1533 344A4 6461 12 4 5 44958 1965 9 609 134 611 581 659 4891 30768 1076 5 3 1~ 39961 1966 348 701 660 tHl9 816 1715 4290 5006 6 1 1 1 14434 1967 26 618 750 771 676 3640 4932 8550 2912 551 9 10 23504 1968 129 &24 664 728 832 11(10 5755 2'7108 5452 9 4 4 42601 1969 105 b 11 59] 787 728 8'72 5117 2450 1000 8 ] 4 12278 19'70 24 855 955 909 144 1005 1160 46710 23142 11 4 5 76126 1971 214 966 1000 1118 979 1846 9705 39596 6859 6 4 38 62])1 1972 589 1409 1372 91'9 1071 4829 5el3 15475 752 5 ] 5 32JJl 1973 654 , 133 973 t098 1017 1208 2005 63999 11068 ]0 16 2]5 814~6 1974 297 1583 1631 1507 ll74 3289 16064 23378 383 4 2 1~ 49!~2 H 1975 668 114 a 973 837 677 ll07 2919 20884 2990 12 4 3:2325 ?; 1976 554 825 915 835 842 t087 5609 17209 755 6 ] 11 28651 1977 94 892 849 801 630 821 1272'7 6556 ! 1 1 1 23]711 t""I t'%j 1978 :n t 791 868 1036 866 1342 2482 25653 4B6 4 2 4 ]180~

H 1979 8S 84~ 949 874 831 973 2288 2197 31 ~ 1 2 8978 H 1980 62 796 84n 848 1051 Be7 8620 10851 45 ~ 1 1 24004 H I .....................................................................•....................•.......•......• 164 705 12B 729 720 1362 5902 14631 2191 49 !5 11 27102 0'\

DEER CREEK PROJ~CT NEW FLOW INTO NOR1H PLATTE CAY)

Scenario 1

YFAPS UCT NOV Dye JAN FEB tl-AR AP~ MAY -.JUNE JULY AUG SE;PT ANN,

........ ........ ........ ........ ...... -- ........ ........ ........ ........ ........ ........ . ....... ........ 1936 0 311 357 2"5 222 326 1185 7!56 163 129 96 78 3889 1937 127 304 :2~2 219 245 352 207 "4 9Ab 6911 1434 l37 279 13511 1938 333 570 5)6 519 455 783 iD43 12370 547 205 159 132 24953 '939 1 b 1 413 452 396 1)6 518 2869 1340 220 151 111 98 7051 1940 6q 235 278 27~ 276 266 19)9 903 129 109 77 63 4518 1941 79 207 225 260 211 359 18)5 18578 9&9 232 478 323 23175 \942 1060 1049 175 606 505 54b 9128 36319 2061 268 202 153 52133 1943 687 694 653 556 506 2094 lA74 911 981 238 189 144 9549 1944 161 367 381 451 453 503 1863 21027 2'66 234 186 142 28536 1945 4u3 495 38!5 413 452 564 1870 23264 7295 346 241 204 159J2 1946 808 673 569 554 483 1389 1886 17098 6335 247 198 188 30428 1947 9 ~6 747 57'7 450 452 1329 2f183 11294 9002 732 330 265 28986 1948 254 626 67) 6'70 604 619 1894 4309 365 177 134 104 10429 1949 102 421 569 558 470 770 1848 9196 1155 229 181 137 15636 19!50 433 560 402 420 485 519 lA70 3078 1909 238 190 145 10110 1951 420 496 445 403 359 377 1970 927 940 238 190 146 6800 1952 149 315 296 403 J89 476 1862 5488 1920 231 192 138 11849 1953 11 ] 190 336 370 322 461 1762 3896 969 229 180 137 8964 1954 114 282 3S0 361 369 546 IPse 911 140 118 84 68 520& 1955 S4 256 264 261 226 318 1833 898 966 227 179 116 5619 1956 113 197 295 2'7~ 280 799 319 32 24 20 16 11 2381 1957 9 116 271 295 305 397 1814 897 965 231 183 140 562] 1958 179 392 383 395 498 SOB 1864 923 13'7 115 82 66 5841 1959 51 1'70 256 229 213 ~A2 1832 89'7 129 109 76 6] 4]06 1960 50 89 32'7 330 276 1854 1831 897 129 109 76 63 60)2 1961 50 86 72 '70 324 444 1441 900 141 118 85 '70 3800 1962 2~2 305 287 381 '750 571 4138 906 974 234 185 142 909'7 1963 219 232 292 428 45! 1145 1544 926 976 215 186 143 6781 1964 123 196 307 358 338 360 1769 '7114 2357 240 192 147 13502 1965 124 3'76 438 3'70 352 388 1861 19185 1563 229 180 161 2522'7 1966 678 474 440 549 502 9'77 1876 932 149 126 92 73 686' 1967 112 394 429 440 383 1990 11:138 2941 4954 122 121 261 14775 1968 414 598 484 501 542 678 1899 29919 7fJ23 242 193 141 4~!5l9 t969 336 410 389 U4 446 516 1869 927 977 240 192 147 6932 1970 t52 517 564 536 443 578 1863 43330 28743 243 195 150 17315 1971 513 604 612 663 582 1040 29)9 47164 9589 237 188 244 64375 19'72 10~0 873 836 bll 647 2661 1881 1'7577 986 246 196 148 37684 1973 1083 708 609 6f)2 610 704 197t 73292 14531 356 275 849 95551 1-3 1974 714 1008 1000 913 826 ,84!) 11463 2!58]0 1~14 26] 206 162 47245 ~ '975 11~0 715 609 ~21 42'7 75a 1873 13730 4917 248 200 15 J 25271 t""4 1976 948 536 573 516 513 614 19'73 13933 980 239 191 167 21105

t'J:j

1977 333 551 52 t '1R6 389 485 3472 8933 144 122 88 70 15593 H 19'78 556 492 524 605 504 756 1946 16315 979 236 188 144 23144 H H 19'79 307 541 532 535 506 574 le6A 925 217 151 114 90 6360 I 1980 230 466 48~ 480 589 501 2725 9 t 1 271 164 125 97 7049 -...J ...................................................................................................•......

359 4!§Q 45l 445 434 774 2534 it 1 ~5 2-"8 255 177 155 20069

DEER CREEK PROJECT ~lEW fLOv~ INTO NORTH PLATTE CAr)

Scenario 2

Y~ARS OCT ~IOV OEC JAN fEB t~AR APR MAY JUNE JULY AUG SEPT ANN, ........ ........ ........ ........ ........ ........ . ....... -.. --_.- ........ ........ ........ . ....... . .......

\930 0 311 357 265 222 32b 1710 369 194 147 11 ] 91 410! 1937 150 322 273 234 261 362 3156 1741 2681 1271 !86 487 11!24 1918 464 831 750 704 619 931 9492 10162 401 257 191 154 24958 1939 149 437 473 422 355 540 4247 \598 256 213 151 123 8965 1940 97 284 320 314 309 2tl9 3'20 1587 224 189 ll3 109 7085 1941 98 260 270 3('5 26R 396 3220 1'75'77 938 345 335 2A3 24296 1942 "99 1107 829 6~5 !4' 5A5 11459 34090 1494 412 323 246 52545 1943 552 835 772 b60 599 2175 3280 710 528 255 199 151 10713 1944 138 366 382 455 455 507 3234 204~3 1706 3q9 316 241 28681 1945 332 b24 493 511 540 642 2712 22765 5466 .'9 344 2'71 )51~9 1946 661 803 682 6!51 570 1462 3290 16960 4509 415 33t 265 )0598 1947 731 910 717 568 557 '420 5690 95tlO 7172 961 !514 413 29243 1948 359 815 828 8(')7 724 728 l311 2124 ]30 2]4 170 1]5 10565 1949 115 458 600 592 495 797 3229 9172 11 5 1 360 280 214 17462 1950 327 66~ 548 499 554 582 326'7 '622 1423 387 ]05 233 10411 1951 330 601 542 491 437 447 21)82 1633 552 303 233 183 7834 1952 160 l59 333 442 419 508 3244 42117 141'7 379 297 227 1~070 1953 187 311 438 46, 403 534 1605 3977 981 351 272 209 9'732 1954 173 lS1 434 438 435 606 l253 1425 220 186 132 107 7'791 1955 85 309 309 305 262 J53 3217 1584 1508 38] 300 229 8144 1956 lil 323 402 371 365 974 327 50 20 16 12 9 2960 1957 7 113 269 ~~J 303 195 1612 1590 1613 195 312 2J9 7139 1958 233 519 491 493 586 896 3268 1622 231 195 '38 112 8'75 1959 87 ,33 309 281 2!i5 322 2725 15B8 227 191 135 110 6464 1960 88 155 3S3 384 320 189'7 3219 1325 209 1'76 123 101 8]78 1961 81 139 116 113 359 479 1255 \ 311 21'7 184 110 107 4490 1962 145 l42 31B 414 778 599 5351 1590 1440 le3 301 211 11891 1963 243 346 ]88 516 533 121b 1397 t 371 1702 ]92 310 237 8650 1964 200 322 414 453 424 4l!5 1614 6229 3100 408 324 347 14171 1965 207 512 553 473 444 469 3267 12258 1]01 371 290 2]0 20375 1966 534 596 545 641 !S8] 1048 3'2'77 1630 244 207 149 120 9575 1967 113 445 471 4B4 419 2016 3223 1587 2469 942 500 404 1307) 1968 436 78) 63' 636 661 796 3316 26710 6126 409 324 247 41069 1969 299 536 496 581 533 593 3274 1627 1231 374 295 326 10064 1970 201 biB 649 615 513 642 1838 41896 26907 410 125 349 '74864 1971 413 744 731 769 677 1123 5708 45641 7755 406 121 378 64565 \9'72 802 1033 976 7]0 751 2750 4927 15652 997 366 28A 320 29491 1973 823 867 743 77 ~ 704 78S 2098 72668 12719 440 365 514 91498 1974 595 10B4 1073 990 889 1898 17014 2)573 642 331 25] 193 48524

~ '975 817 83~ 709 603 494 817 3003 13292 309] 419 336 257 24674 t97D 752 719 728 646 627 732 3287 1360, 997 363 285 227 22965 t'"' 19'7 268 D2D 586 549 444 536 5735 6710 236 200 142 115 16147 t%j 1978 357 569 588 664 552 8~2 2534 16792 724 328 254 198 24363 H 1979 217 604 585 598 550 016 2360 1618 265 219 159 128 79]0 H H 1980 160 506 519 ~24 619 531 4106 1593 271 220 160 129 9J18 I .........•.....•.•••.......•.......•...................................•.................•........••...... 00 115 546 53' 519 498 8]2 3126 10600 2397 360 261 211 20800

1. INTRODUCTION

SECTION IV

NORTH PLATTE RIVER WATER RIGHTS EFFECT ON PROJECT YIELD

A reservoir on Deer Creek must be operated so as not to interfere

with senior downstream water rights. Legally, only those flows which are sur-

plus to senior water rights requirements in Wyoming and are physically avail-

able can be stored in a Deer Creek Reservoir. In the previous section, the

estimate of the Project storable flow and resulting firm yield are based on

first satisfying Deer Creek water rights which would be senior to a Project

filing. Irrigation return flow was a consideration in estimating this stor-

able flow. The flow in excess of Deer Creek Basin water rights historically

has been used to satisfy water rights requirements of the North Platte River

Basin (North Platte) of which Deer Creek is a part. Thus, only those Deer

Creek flows which are physically available at the Project site and are surplus

to water rights requirements can be considered as storable for the Project.

In estimating surplus flow, Wyoming water law and the stipulations

of the U.S. Supreme Court North Platte Decree (Decree) as amended in 1952 must

be considered. The Decree deals with natural flows in the North Platte.

Tributaries downstream of Pathfinder Reservoir are not covered by the Decree

which, among other things, sets priori ties for reservoir filling and direct

diversions to lands in Nebraska and establishes the length of the irrigation

season. Deer Creek enters the North Platte downstream of Pathfinder Reser-

voir. In this section, Project yield is estimated based on the flow that is

surplus to North Platte water rights including rights within the Deer Creek

Basin as considered in the Section III analyses.

The Wyoming Attorney General's office, in a letter to the Chairman

of WWDC, dated December 6, 1983, indicated that the Decree does not prohibit

IV-2

Wyoming from constructing a reservoir on Deer Creek. The opinion, however,

stated that a Deer Creek reservoir may be subject to regulation to provide

water for senior downstream Wyoming water rights. The letter pointed out that

decisions on operation of the Project will be made by the State Engineer and

that Deer Creek or any other tributary below Pathfinder Reservoir has never

before been regulated to supply main stem priori ties. A copy of the Decem-

ber 6, 1983 letter is included in Appendix C.

This section summarizes the results of initial preliminary yield

studies for the Deer Creek Reservoir considering as storable flow that part of

the North Platte flow available at the Project which is surplus to water

rights and Decree requirements. The studies are engineering in nature and are

not to be construed as interpreting legal considerations. Additional legal

and hydrologic studies as outlined at the end of this section will be neces-

sary before Project yield can be quantified with sufficient accuracy to estab-

lish final feasibility of the Project.

2. THE NORTH PLATTE SYSTEM

The North Platte River within the State of Wyoming has supplied

irrigation water historically for use in both Wyoming and Nebraska. To in-

crease the availability and distribution of water, the USBR has constructed

five storage reservoirs on the river in Wyoming and several large canal sys-

tems. Three of the reservoirs, Seminoe, Pathfinder, and Alcova, are located

upstream of the river's confluence with Deer Creek and two, Glendo and

Guernsey, are downstream. Construction and operation of the Project could

affect (1) storage rights at Glendo and Guernsey, (2) direct withdrawals from

the North Platte in Wyoming, and (3) diversions to both Wyoming and Nebraska

via various canal systems.

The North Platte System operation is based on criteria set by

agreement between the States of Wyoming and Nebraska, and the USBR. These

criteria are consistent with the Decree and Wyoming water rights except that

IV-3

through agreement, water has been diverted from the North Platte River within

Wyoming in the amount of up to 46,000 ac-ft for storage in the Inland Reser-

voirs (known as Lakes Alice and Minatare) located in Nebraska. The details of

reservoir operations including division of water between reservoirs and

Wyoming and Nebraska, direct diversions, storage ownership, carryover storage

requirements, power operations, determining surplus flows, estimating irriga-

tion requirements, etc. are complex and should be addressed in future studies.

3. USBR STUDY

The USBR has developed a computer model which simulates the opera-

tion of the North Platte System based on monthly historical hydrologic data,

Wyoming water rights, the Decree, and river operating criteria. At the

request of WWDC in March 1983, the USBR operated the model to test the effects

of a potential Deer Creek Reservoir on the North Platte. As input, the USBR

used flows to the North Platte from Deer Creek adjusted for the effects of a

Deer Creek Reservoir as determined in Section III herein. These flows are

given in Tables 111-7 and 111-8. Historical inflow from Deer Creek to the

North Platte is shown in Table 111-1.

The USBR, in its letter of November 15, 1983 to Jon Wade of the

WWDC staff, indicated that the model does not produce meaningful results using

the adjusted Deer Creek inflow data (Tables 111-7 and 111-8) because of pro-

gramming problems which it was unable to solve after several months of work.

A copy of the letter is included in Appendix C. The USBR conducted another

study of the effect of the Project on the North Platte System and summarized

it in the same letter. This study was based on annual, rather than monthly,

hydrologic and operational data as extracted from the results of its North

Platte Simulation Model Study No. 1141 (Run 1141), and on the results of the

operation study of the Project summarized in Section III and Appendix B here-

in. As noted previously, flows in Tables 111-7 and 111-8 represent the

effects of the Project operated so as to satisfy Deer Creek Basin water rights

but not those on the main stem North Platte.

IV-4

After reviewing the results of this USBR study, it is concluded

that the study based on annual data does not adequately reflect the effects

that the Project would have on downstream water rights and that a more

detailed analysis is required.

4. RESERVOIR YIELD BASED ON SURPLUS RIVER WATER

Based on discussions with USBR personnel, it is concluded that the

"Gain to the River" (Gains) estimated in its Run 1141 (page 19 of the run)

represents river flows which are surplus to the requirements of Wyoming water

rights, the Decree, and the