Water Supply Outlook - CNRFC · General Outlook May 1, 2001 California benefitted from a series of April storms that brought above normal monthly precipitation to several regions

Water Supply Outlook

California Nevada River Forecast Center NOAA National Weather Service Sacramento, California

May 22000011

DEFINITIONS: Acre-Feet: The volume equal to one acre covered one foot deep (43,560 cubic feet). Forecast Period: Generally, April 1st through July 31st, unless otherwise noted. April-High Forecast Period: For the Lake Tahoe Stage Rise, the period from April 1st to the highest recorded lake stage level. April 1st Average: The April 1st snowpack average is used as a reference point because it is normally the end of the winter snowfall season and the beginning of the spring runoff season. Residual Period: The forecast period from the first of the current month through September 30th. Probability Forecasts: Precipitation and snowfall accumulation of known probability as determined by analysis of past records are utilized in the preparation of probability runoff forecasts. The forecasts include an evaluation of the standard error of the prediction model. The forecasts are presented at three levels of probability as follows:

• Most Probable Volume: Given the current hydrometeorological conditions to date, this is the best estimate of what the actual runoff volume will be this season.

• Most Probable Volume (% Normal): Most probable volume in percent of the 1961-1990 average.

• Reasonable Maximum Volume: Given current hydrometeorological conditions, the seasonal runoff that has a 10 percent chance of being exceeded.

• Reasonable Minimum Volume: Given current hydrometeorological conditions, the seasonal runoff that has a 90 percent chance of being exceeded.

SNOTEL: Acronym for SNOw TELemetry. This is a automated snow measurement system operated by the USDA - Natural Resources Conservation Service. These sites use meteor burst communications technology to transmit hydrometeorological information such as snow water equivalent from snow pillows, accumulated precipitation and maximum, minimum and average air temperature. Water equivalent: The depth of water that would result from melting the snowpack at a point. Water Year: The period from October 1st through September 30th.

General Outlook

May 1, 2001

California benefitted from a series of April storms that brought above normal monthly precipitation to several regions in the state. Stormy periods between April 6th-8th and 19th-21st brought some minor accumulations to the snowpack, especially in the central and southern Sierra Nevada. A period of well above normal temperatures followed near the end of April resulting in an accelerated melting of the snowpack. Monthly precipitation ranged from 175 percent in the Tulare Lake basin, 135 percent in the San Joaquin basin, tapering off to only 5 percent in the southeast California deserts. The statewide average was 95 percent, which brought the seasonal average to about 77 percent of normal.

The Sierra Nevada snowpack on May 1st ranged from 50 percent of average in the north to 60 percent in the south. In eastern California and northern Nevada, the snowpack was measured at about 60 percent of average in the Carson-Walker basins, 40 percent of average in the Tahoe-Truckee basins, and 55 percent in the Humboldt basin. The 25 percent of average snowpack in the Upper Klamath of southern Oregon ranks among the lowest of its historical record.

Runoff amounted to about 55 percent of the monthly average, a decrease of about 12 percent from last month. The seasonal average now stands at 46 percent.

The statewide reservoir storage is about 98 percent of the montly average, or about 71 percent of capacity. It was 116 percent of monthly average at this same time last year.

The spring and summer runoff for California is expected to be below to much below average this year, due primarily to the rather dismal start of the precipitation season and the below normal snowpack. April-July forecasts for California watersheds remain much below average, ranging from 65 percent for the McCloud River above Lake Shasta to 41 percent in the Cosumnes River basin. Streamflow forecasts remain much below average along the Sierra Nevada east slopes and the Humboldt basin. Extremely dry conditions still exist in the Upper Klamath basin, where the March-September forecast is expected to remain much below average.

Please note: This will be the last Water Supply Outlook issued for the water year 2001. The Water Supply Outlook is available on the World Wide Web at http://www.wrh.noaa.gov/cnrfc.

Pit R.abv Shasta

McCloud R.abv Shasta

Sacramento R.abv Shasta

Sacramento R.Shasta Lk. nr Redding

Lake OrovilleReservoir Inflow

Folsom ReservoirInflow

Sacramento R.nr Red Bluff

NF Feathernr Prattville

NF Feathernr Big Bar

MF American R.nr Auburn

Silver Creekat Union Valley

Silver Creekblo Camino Div. Dam

Sacramento

NF Yuba R.blo Goodyears Bar

SF Yuba R.at Langs Crossing

Lake Shasta

To Delta

Trinity Lake

Trinity R

Upper Klamath

Lake

Williamson R blo Sprague R

Sprague R nr Chiloquin

Klamath R Upper Lake Inflow

Trinity Lake Inflow

Water Supply Forecasts Most Most Reas Reas. 30 Prob. Prob. Max. Min. Year Vol. Vol. Vol. Vol. Avg. KAF %Nrml KAF KAF KAF ____________________________________________________________________________________ COASTAL BASINS Williamson River Sprague, blo Mar-Sep 230 46 325 134 504 Sprague River Chiloquin, nr Mar-Sep 88 30 180 35 292 Upper Klamath Falls River Inflow Mar-Sep 320 45 465 175 706 Trinity River Trinity Lake Inflow Apr-Jul 420 68 515 325 615 SACRAMENTO RIVER BASIN SACRAMENTO RIVER ABOVE BEND BRIDGE Pit River Montgomery Ck, nr Apr-Jul 720 68 845 580 1054 Mccloud River Shasta Lk, abv Apr-Jul 300 77 385 215 390 Sacramento River Delta Apr-Jul 215 77 305 125 279 Shasta Lake, Redding, nr Apr-Jul 1300 74 1700 900 1759 Bend Bridge, abv, Red Bluff Apr-Jul 1620 67 2290 1300 2411 FEATHER RIVER ABOVE OROVILLE RESERVOIR NF Feather River Prattville, nr Apr-Jul 165 50 235 140 333 Big Bar Apr-Jul 500 52 740 380 962 Feather River Oroville Reservoir Inflow Apr-Jul 820 47 1300 700 1746

Water Supply Forecasts

Most Most Reas Reas. 30 Prob. Prob. Max Min Year Vol. Vol. Vol. Vol. Avg. KAF %Nrml KAF KAF KAF ____________________________________________________________________________________ Yuba River above Smartville North Yuba River Goodyears Bar, blo Apr-Jul 160 59 200 119 273 South Yuba River Langs Crossing Apr-Jul 140 62 205 74 225 Yuba River Smartville, nr Apr-Jul 590 60 770 410 980 American River above Folsom Reservoir MF American River Auburn, nr Apr-Jul 290 59 445 170 490 Silver Ck Union Valley Apr-Jul 54 55 76 32 98 Camino Dam, blo Apr-Jul 87 55 126 55 158 American River Folsom Reservoir Inflow Apr-Jul 670 56 890 450 1199

Sacramento/Trinity/Klamath River Basins

Seasonal Basin PrecipitationOctober 1 to Date

6864

55

70

5451

0

10

20

30

40

50

60

70

80

American Yuba Feather Upper Sac Trinity Klamath

Per

cen

t of A

vera

ge

Seasonal Basin SnowpackWater Content in % of April 1 Average

22

40

8065

40

110

150

190

220

190

45

70

90100

80

1025

3520

0

50

100

150

200

250

1-Jan 1-Feb 1-Mar 1-Apr 1-May

Per

cen

t of A

vera

ge

Observed Maximum Average Minimum

Sacramento/Trinity/Klamath River Basins

Basin Reservoir StorageContents of Major Reservoirs in % of Average

91

104

75

10097

101

0

20

40

60

80

100

120


Per

cen

t of A

vera

ge

Seasonal Basin RunoffOctober 1 to Date

4340

45

65

5357

0

10

20

30

40

50

60

70


Per

cen

t of A

vera

ge

Modesto

SacramentoCosumnes R.at Michigan Bar

NF Mokelumne R.at West Point

Mokelumne R.at Mokelumne Hill

MF Stanislaus R.blo Beardsley Dam

Stanislaus R.blo Goodwin Dam

Tuolumne R.nr Hetch Hetchy

Merced R.at Pohono Bridge

nr YosemiteLake McClure

Inflow

San Joaquin R.blo Friant

SF San Joaquin R.nr Florence Lake

Tuolumne R.at La Grange Dam

Fresno

Merced

Don PedroLake

MillertonLake

NewMelones

Lake

CamancheReservoir

S A N J O A Q U I N R I V E R


Most Most Reas Reas. 30 Prob. Prob. Max. Min. Year Vol. Vol. Vol. Vol. Avg. KAF %Nrml KAF KA KAF ____________________________________________________________________________________ SF San Joaquin River Hooper Ck, blo, Florence Lake Apr-Jul 135 70 200 68 192 San Joaquin River Millerton Lk Apr-Jul 860 70 940 780 1237 Merced River Pohono Bridge, at, Yosemite Apr-Jul 270 75 315 225 360 Merced Falls, blo Apr-Jul 450 73 545 355 620 Tuolumne River Hetch Hetchy, nr Apr-Jul 430 72 485 375 596 La Grange, nr Apr-Jul 840 71 940 740 1189 MF Stanislaus River Beardsley Dam, blo Apr-Jul 200 62 255 147 320 Stanislaus River Goodwin Dam, blo, Knights Ferry Apr-Jul 430 62 515 345 689 NF Mokelumne River West Point Apr-Jul 230 55 290 171 416 Mokelumne River Mokelumne Hill Apr-Jul 250 56 310 189 450 Cosumnes River Michigan Bar Apr-Jul 50 41 109 24 122

San Joaquin Basin


85

81 81

74

83

68

70

72

74

76

78

80

82

84

86

San Joaquin Merced Tuolumne Stanislaus Mokelumne

Per

cen

t of A

vera

ge


16

41

70 6752

120

170

210

230

210

40

65

90100

70

515

30 30

0

50

100

150

200

250


Per

cen

t of A

vera

ge


San Joaquin Basin


133

115120

133

106

0

20

40

60

80

100

120

140


Per

cen

t of A

vera

ge

Season Basin RunoffOctober 1 to Date

63

57

62

57

50

0

10

20

30

40

50

60

70


Per

cen

t of A

vera

ge

Bakersfield

Kern R.nr Bakersfield

Kern R.blo Isabella Dam

Kern R.nr Kernville

Tule R.blo Success Dam

Kaweah R.Terminus Resevoir

Inflow

Kings R.blo Pine Flat Dam

NF Kings R.nr Cliff Camp

Visalia


Most Most Reas Reas. 30 Prob. Prob. Max. Min. Year Vol. Vol. Vol. Vol. Avg. KAF %Nrml KAF KAF KAF ____________________________________________________________________________________ Kern River Kernville, nr Apr-Jul 240 60 315 164 398 Isabella Dam, blo Apr-Jul 270 56 405 137 484 Bakersfield, nr Apr-Jul 280 56 420 132 499 Tule River Success Dam Apr-Jul 35 54 59 10 65 Kaweah River Terminus Dam Apr-Jul 185 64 235 137 290 NF Kings River Cliff Camp, nr Apr-Jul 170 70 210 131 243 Kings River Pine Flat Dam, blo Apr-Jul 840 68 950 730 1230

Tulare Lake Basin

Seasonal PrecipitationOctober 1 to Date

79

80

83

77

74

75

76

77

78

79

80

81

82

83

84

Kern Tule Kaweah Kings

Per

cent

of A

vera

ge


9

39

81

62

43

120

170

210

230

210

40

65

90100

70

515

30 30

0

50

100

150

200

250


Per

cent

of A

vera

ge


Tulare Lake Basin


84

101

160

108

0

20

40

60

80

100

120

140

160

180


Per

cent

of A

vera

ge


56

45

65

60

0

10

20

30

40

50

60

70


Per

cent

of A

vera

ge

Reno/Sparks

Pyramid Lake

WalkerLake

Lake TahoeStage Rise

Lake Lahontan

Little Truckee R.abv Boca

Truckee R.at Farad

EF Carson R.nr Gardnerville

WF Carson R.at Woodfords

LakeTahoe

Carson R.nr Carson City

Carson R.nr Ft. Churchill

EF Walker R.nr Bridgeport

WF Walker R.blo Little Walker R.

nr Coleville

Water Supply Forecasts Most Most Reas Reas. 30 Prob. Prob. Max Min Year Vol. Vol. Vol. Vol. Avg. KAF %Nrml KAF KAF KAF ____________________________________________________________________________________ Truckee River Truckee River Lake Tahoe Stage Rise Apr-High 0.4 29 0.6 0.2 1.4 Farad Apr-Jul 75 29 105 55 263 Carson River EF Carson River Gardnerville, nr Apr-Jul 80 43 97 63 186 WF Carson River Woodfords Apr-Jul 22 41 28 18 54 Carson River Carson City, nr Apr-Jul 50 27 80 20 182 Fort Churchill, nr Apr-Jul 30 18 64 10 167 Walker River East Walker River Bridgeport, nr Apr-Aug 27 36 43 11 74 West Walker River Ltl Walker, blo, Coleville Apr-Jul 80 54 91 69 147

East Side Sierra Nevada Basins


6570 70

56

0

10

20

30

40

50

60

70

80

Truckee Carson East Walker West Walker

Per

cen

t of A

vera

ge

Basin Snowpack% of Average SWE to Date

45 47

58

40 40

32

45

62

56

63

0

10

20

30

40

50

60

70


Per

cen

t of A

vera

ge

Truckee-Tahoe Carson-Walker

East Side Sierra Nevada Basins


42

59

70

79

0

10

20

30

40

50

60

70

80

90

Truckee Carson East Walker West Walker

Per

cent

of

Ave

rage

Humboldt River Basin

Winnemucca

Martin Creeknr Paradise Valley

Humboldt R.at Comus

Humboldt R.at PalisadeTo Rye Patch

ReservoirSF Humboldt R.abv Dixie Creek

nr Elko

NF Humboldt R.at Devil’s Gate

nr Halleck

Elko


Most Most Reas Reas. 30 Prob. Prob. Max Min Year Vol. Vol. Vol. Vol. Avg. KAF %Nrml KAF KAF KAF ____________________________________________________________________________________ NF Humboldt River Devils Gate, at, Halleck, nr Apr-Jul 12 35 26 5 34 SF Humboldt River Dixie Ck, abv, Elko, nr Apr-Jul 36 53 63 12 68 Humboldt River Palisade Apr-Jul 85 35 199 25 245 Comus Apr-Jul 50 24 194 20 209 Martin Ck Paradise Valley, nr Apr-Jul 6 33 11.4 3.5 18

Humboldt River Basin


89

76

92

113

0

20

40

60

80

100

120

Martin Creek SF Humboldt NF Humboldt Humboldt

Per

cen

t of A

vera

ge

Basin Snowpack% of Average SWE to Date

70

81

73

60

54

0

10

20

30

40

50

60

70

80

90


Per

cen

t of A

vera

ge

Documents

Water Supply Outlook - CNRFC · General Outlook May 1, 2001 California benefitted from a series of April storms that brought above normal monthly precipitation to several regions