B120UP.201204 (04/26/12 1024)
DEPARTMENT OF WATER RESOURCES
California Cooperative Snow Surveys
WATER SUPPLY FORECAST UPDATE
2012 April-July Unimpaired Runoff (1,000 Acre-feet)
Apr 1 %Avg Apr 10 %Avg Apr 17 %Avg Apr 24 %Avg
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Shasta Lake, Total Inflow average = 1806
90% Exceedance 1110 61% 1120 62% 1390 77% 1340 74%
50% Exceedance 1460 81% 1430 79% 1680 93% 1600 89%
10% Exceedance 2160 120% 2060 114% 2260 125% 2090 116%
Sacramento River, above Bend Bridge (near Red Bluff) average = 2485
90% Exceedance 1500 60% 1500 60% 1840 74% 1770 71%
50% Exceedance 1900 76% 1860 75% 2180 88% 2080 84%
10% Exceedance 3020 122% 2840 114% 3010 121% 2760 111%
Feather River at Oroville average = 1758
90% Exceedance 800 46% 810 46% 1000 57% 950 54%
50% Exceedance 1040 59% 1040 59% 1220 69% 1170 67%
10% Exceedance 1890 108% 1760 100% 1840 105% 1680 96%
Yuba River near Smartsville average = 996
90% Exceedance 490 49% 490 49% 640 64% 590 59%
50% Exceedance 660 66% 650 65% 790 79% 730 73%
10% Exceedance 1060 106% 980 98% 1060 106% 940 94%
American River, below Folsom Lake average = 1231
90% Exceedance 480 39% 480 39% 620 50% 600 49%
50% Exceedance 680 55% 670 54% 800 65% 760 62%
10% Exceedance 1330 108% 1190 97% 1210 98% 1070 87%
Mokelumne River, Inflow to Pardee Reservoir average = 461
90% Exceedance 160 35% 160 35% 200 43% 190 41%
50% Exceedance 230 50% 220 48% 260 56% 240 52%
10% Exceedance 380 82% 340 74% 360 78% 310 67%
Stanislaus River, below Goodwin Res. (blw New Melones) average = 699
90% Exceedance 215 31% 210 30% 260 37% 250 36%
50% Exceedance 320 46% 310 44% 360 52% 340 49%
10% Exceedance 570 82% 520 74% 530 76% 480 69%
Tuolumne River, below La Grange Res. (blw Don Pedro) average = 1221
90% Exceedance 415 34% 420 34% 550 45% 520 43%
50% Exceedance 570 47% 570 47% 680 56% 640 52%
10% Exceedance 950 78% 890 73% 950 78% 860 70%
Merced River, below Merced Falls (blw Lake McClure) average = 636
90% Exceedance 175 28% 180 28% 280 44% 260 41%
50% Exceedance 270 42% 270 42% 360 57% 330 52%
10% Exceedance 500 79% 470 74% 530 83% 470 74%
San Joaquin River, below Millerton Lake average = 1258
90% Exceedance 390 31% 390 31% 510 41% 490 39%
50% Exceedance 570 45% 560 45% 680 54% 650 52%
10% Exceedance 900 72% 850 68% 930 74% 860 68%
Kings River, below Pine Flat Reservoir average = 1236
90% Exceedance 380 31% 390 32% 530 43% 520 42%
50% Exceedance 530 43% 530 43% 660 53% 630 51%
10% Exceedance 820 66% 770 62% 860 70% 790 64%
Kaweah River, below Terminus Reservoir average = 290
90% Exceedance 90 31% 90 31% 130 45% 140 48%
50% Exceedance 140 48% 135 47% 170 59% 170 59%
10% Exceedance 260 90% 240 83% 260 90% 240 83%
Tule River, below Lake Success average = 64
90% Exceedance 15 24% 17 27% 35 55% 32 50%
50% Exceedance 29 46% 29 46% 45 71% 40 63%
10% Exceedance 70 110% 65 102% 77 121% 69 109%
Kern River, inflow to Isabella Lake average = 465
90% Exceedance 150 32% 150 32% 220 47% 220 47%
50% Exceedance 220 47% 220 47% 280 60% 270 58%
10% Exceedance 340 73% 320 69% 370 80% 350 75%
Questions regarding this forecast:
John King: (916) 574-2637 (e-mail kingjj@water.ca.gov)
Steve Nemeth: (916) 574-2634 (e-mail nemeth@water.ca.gov)
Dave Rizzardo: (916) 574-2983 (e-mail daver@water.ca.gov)
Andy Reising: (916) 574-2181 (e-mail areising@water.ca.gov)
Runoff forecasts are unimpaired (full natural) flows which represent the
natural water production of the river basin, unaltered by upstream diversions,
storage, or export or import of water to or from other watersheds.
The median (50%) forecast assumes median conditions after the date of forecast.
Runoff exceedance levels are derived from historical data.
The 90 percent exceedance level and the 10 percent exceedance level together
comprise a range about the median forecast in which the actual runoff should
fall 8 times out of 10.
Forecasts are stated in 1,000's of acre-feet and percent of (50-year) average.
The averages are for the period 1961 to 2010.
