Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (06/01/2015)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2014): 35.19      
Average to Date: 47.60      
Percent of Average to Date: 74 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 70 %  

(1) Northern Sierra (Sacramento, Feather, Yuba, and American River Basins)

Snowpack Water Content
Region
Water Content
(in inches)
%
Avg to Date
%
April 1 Avg (2)
Northern Sierra 0.00                   0                   0                  
Central Sierra 0.00                   0                   0                  
Southern Sierra 0.00                   0                   0                  
Statewide 0.00                   0                   0                  

(2) April 1 is the date of normal maximum accumulation for the season.

Forecast of Regional Water Supply Indices (3)
Index Value Year Type
8 River Index for May (in 1000 AF)828.5       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%4.0       Critical
Sacramento Valley Water Year Type Index (40-30-30) @ 90%3.8       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%0.7       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%0.7       Critical

(3) For more information see Sacramento & San Joaquin Valley Water Year Type Index forecast: Latest | Previous
    (Issued monthly from December 1 through May 1)

Key Reservoir Storage As of 05/31/2015 midnight
Reservoir River Storage
(in 1000 AF)
Avg Storage
(in 1000 AF)
%
Average
Capacity
(in 1000 AF)
%
Capacity
Flood Control (4)
Encroachment
(in 1000 AF)
Trinity Lake Trinity 1,024   2,114   48   2,448   42   ---      
Shasta Lake Sacramento 2,404   3,901   62   4,552   53   -2,148      
Lake Oroville Feather 1,565   2,990   52   3,538   44   -1,973      
New Bullards Bar Res Yuba 558   837   67   930   60   -408      
Folsom Lake American 535   821   65   977   55   -442      
New Melones Res Stanislaus 453   1,519   30   2,400   19   -1,967      
Don Pedro Res Tuolumne 826   1,553   53   2,030   41   -1,176      
Lake McClure Merced 129   701   18   1,025   13   -838      
Millerton Lake San Joaquin 177   403   44   520   34   -343      
Pine Flat Res Kings 265   722   37   1,000   27   -735      
Isabella Kern 44   299   15   568   8   -318      
San Luis Res (Offstream) 1,090   1,617   67   2,041   53   ---      

(4) Temporary encroachment into seasonally reserved flood storage space; requirements can vary considerably on a daily basis due to numerous variables: rainfall amounts, anticipated snowmelt, time of year, soil moisture, etc.

Daily Precipitation (in inches) for Selected Stations as of 06/01/2015

Station
Oct 1 to Date
2014 - 2015
%
Average
Season to Date
2013 - 2014
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta33.558212.052977
Eureka29.867816.884474
Redding22.516816.124965
South Lake Tahoe11.656413.157257
Sacramento Executive Airport15.37868.925083
Santa Rosa (Sonoma Co AP)22.256313.703861
San Francisco17.437511.955174
Stockton10.58776.995175
Yosemite15.644316.484641
Monterey14.51928.305390
Paso Robles8.21664.914064
Fresno6.42584.914456
Bakersfield5.29842.413882
Death Valley1.05551.025444
Los Angeles8.39585.743956
Riverside4.83411.871639
Palm Springs2.19460.921938
San Diego8.73874.904984
Comments
As of May 31, statewide hydrologic conditions were as follows: precipitation, 75 percent of average to date; runoff, 50 percent of average to date; snow water content, 0 percent of average to date (0 percent of the April 1 average); and reservoir storage, 60 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2015, observed through May 31, 2015 was about 8.0 million acre-feet (MAF), which is about 51 percent of average. In comparison to Water Year 2014, the observed Sacramento River Region unimpaired runoff through May 31, 2014 was about 6.2 MAF, or about 40 percent of average. On May 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 35.2 inches, which is about 74 percent of the seasonal average to date and 70 percent of an average water year (50.0 inches). During May, the total precipitation for the 8-Stations was 1.2 inches, or about 57 percent of average for the month. Last year on May 31, the Water Year 2014 seasonal total for the 8-Stations was 28.8 inches, or about 61 percent of average. On May 31, the San Joaquin 5-Station Precipitation Index Water Year total was 17.4 inches, which is about 45 percent of the seasonal average to date and 43 percent of an average water year (40.8 inches). During May, the total precipitation for the 5-Stations was 1.4 inches, or about 78 percent of average for the month. Last year on May 31, the Water Year 2014 seasonal total for the 5-Stations was 19.2 inches, or about 49 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for June 2015, issued May 31, 2015, suggests equal chances of wet or dry conditions for almost all of California, except for the extreme northwest portion of the State where below average precipitation is suggested. Updates to the Executive Summary will generally be issued approximately weekly, biweekly, or monthly (depending on conditions) through the wet months of winter and spring. Beginning about June 1, this product is updated monthly through the dry seasons of summer and fall. The next update of this product will be issued about Monday, July 13, 2015, for conditions on July 1, unless there are significant hydrologic changes.


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