B120UP (04/25/13 0748)
DEPARTMENT OF WATER RESOURCES
California Cooperative Snow Surveys

WATER SUPPLY FORECAST UPDATE
2013 April-July Unimpaired Runoff    (1,000 Acre-feet)

                 Apr 1  %Avg Apr 16  %Avg Apr 23  %Avg                          
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Shasta Lake, Total Inflow                                       average =   1806
 90% Exceedance    880   49%    940   52%    900   50%                          
 50% Exceedance   1230   68%   1230   68%   1160   64%                          
 10% Exceedance   2030  112%   1830  101%   1670   92%                          

Sacramento River, above Bend Bridge (near Red Bluff)            average =   2485
 90% Exceedance   1110   45%   1220   49%   1190   48%                          
 50% Exceedance   1630   66%   1630   66%   1550   62%                          
 10% Exceedance   2800  113%   2480  100%   2250   91%                          

Feather River at Oroville                                       average =   1758
 90% Exceedance    590   34%    630   36%    600   34%                          
 50% Exceedance    970   55%    950   54%    900   51%                          
 10% Exceedance   1820  104%   1580   90%   1430   81%                          

Yuba River near Smartsville                                     average =    996
 90% Exceedance    250   25%    280   28%    280   28%                          
 50% Exceedance    520   52%    480   48%    450   45%                          
 10% Exceedance    920   92%    760   76%    670   67%                          

American River, below Folsom Lake                               average =   1231
 90% Exceedance    320   26%    350   28%    340   28%                          
 50% Exceedance    600   49%    570   46%    540   44%                          
 10% Exceedance   1250  102%   1000   81%    860   70%                          

Mokelumne River, Inflow to Pardee Reservoir                     average =    461
 90% Exceedance    180   39%    180   39%    180   39%                          
 50% Exceedance    260   56%    240   52%    230   50%                          
 10% Exceedance    410   89%    340   74%    310   67%                          

Stanislaus River, below Goodwin Res. (blw New Melones)          average =    699
 90% Exceedance    300   43%    300   43%    290   41%                          
 50% Exceedance    420   60%    410   59%    390   56%                          
 10% Exceedance    670   96%    590   84%    530   76%                          

Tuolumne River, below La Grange Res. (blw Don Pedro)            average =   1221
 90% Exceedance    570   47%    600   49%    580   48%                          
 50% Exceedance    740   61%    730   60%    700   57%                          
 10% Exceedance   1130   93%   1010   83%    930   76%                          

Merced River, below Merced Falls (blw Lake McClure)             average =    636
 90% Exceedance    210   33%    220   35%    210   33%                          
 50% Exceedance    310   49%    300   47%    280   44%                          
 10% Exceedance    550   86%    480   75%    420   66%                          

San Joaquin River, below Millerton Lake                         average =   1258
 90% Exceedance    420   33%    410   33%    380   30%                          
 50% Exceedance    610   48%    580   46%    540   43%                          
 10% Exceedance    950   76%    840   67%    760   60%                          

Kings River, below Pine Flat Reservoir                          average =   1236
 90% Exceedance    360   29%    370   30%    350   28%                          
 50% Exceedance    520   42%    500   40%    470   38%                          
 10% Exceedance    820   66%    710   57%    630   51%                          

Kaweah River, below Terminus Reservoir                          average =    290
 90% Exceedance     60   21%     65   22%     60   21%                          
 50% Exceedance    100   34%     95   33%     90   31%                          
 10% Exceedance    220   76%    180   62%    160   55%                          

Tule River, below Lake Success                                  average =     64
 90% Exceedance      2    3%      5    8%      5    8%                          
 50% Exceedance     10   16%      9   14%      8   13%                          
 10% Exceedance     55   87%     40   63%     30   47%                          

Kern River, inflow to Isabella Lake                             average =    465
 90% Exceedance     65   14%     65   14%     55   12%                          
 50% Exceedance    120   26%    110   24%     95   20%                          
 10% Exceedance    240   52%    200   43%    180   39%                          


Questions regarding this forecast:
    John King:     (916) 574-2637 (e-mail John.J.King@water.ca.gov)
    Steve Nemeth:  (916) 574-2634 (e-mail Stephen.Nemeth@water.ca.gov)
    Dave Rizzardo: (916) 574-2983 (e-mail David.Rizzardo@water.ca.gov)
    Andy Reising:  (916) 574-2181 (e-mail Andrew.Reising@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.