Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (08/31/2016)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2015): 57.82      
Average to Date: 49.10      
Percent of Average to Date: 118 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 116 %  

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


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

Forecast of Regional Water Supply Indices (2)
Index Value Year Type
8 River Index for August (in 1000 AF)345.8       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%7.1       Below Normal
Sacramento Valley Water Year Type Index (40-30-30) @ 90%6.8       Below Normal
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%2.5       Dry
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%2.4       Dry

(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 08/31/2016 midnight
Reservoir River Storage
(in 1000 AF)
Avg Storage
(in 1000 AF)
%
Average
Capacity
(in 1000 AF)
%
Capacity
Flood Control (3)
Encroachment
(in 1000 AF)
Trinity Lake Trinity 1,060   1,803   59   2,448   43   ---      
Shasta Lake Sacramento 3,132   2,878   109   4,552   69   -1,420      
Lake Oroville Feather 1,840   2,318   79   3,538   52   -1,698      
New Bullards Bar Res Yuba 677   653   104   966   70   -289      
Folsom Lake American 347   611   57   977   35   -630      
New Melones Res Stanislaus 544   1,387   39   2,400   23   -1,876      
Don Pedro Res Tuolumne 1,367   1,436   95   2,030   67   -663      
Lake McClure Merced 439   564   78   1,025   43   -580      
Millerton Lake San Joaquin 259   236   110   520   50   -261      
Pine Flat Res Kings 197   378   52   1,000   20   -803      
Isabella Kern 106   216   49   568   19   -256      
San Luis Res (Offstream) 322   858   38   2,041   16   ---      

(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 08/31/2016

Station
Oct 1 to Date
2015 - 2016
%
Average
Season to Date
2014 - 2015
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta40.939535.098294
Eureka44.0111130.4877109
Redding37.3011023.1268108
South Lake Tahoe22.1311213.9171109
Sacramento Executive Airport16.148915.438587
Santa Rosa (Sonoma Co AP)30.438522.356284
San Francisco22.169517.667594
Stockton16.6012110.6878118
Yosemite36.079718.424995
Monterey21.5413514.6192134
Paso Robles7.37598.406758
Fresno14.331266.5057125
Bakersfield5.44855.298384
Death Valley1.68781.054971
Los Angeles6.35438.675943
Riverside5.17435.824842
Palm Springs2.50472.504744
San Diego7.737610.039875
Updated Information and Data
Daily Drought Information Summary
Daily Statewide Hydrologic Update(Interactive)
Weekly Update to Unimpaired Runoff Forecast (Feb - Jun)
Unimpaired Forecast Discussion (Weekly/Monthly, Dec - June)
Bulletin 120, Water Conditions in California (Monthly, Feb - May)
Comments
 
Statewide Hydrologic Conditions (As of August 31)
As of August 31, statewide hydrologic conditions were as follows: precipitation, 110 percent of average to date; runoff, 95 percent of average to date; and reservoir storage, 85 percent of average for the date.
 
Sacramento River Unimpaired Runoff
Sacramento River Region unimpaired runoff, for Water Year 2016, observed through August 31, 2016 was about 17.1 million acre-feet (MAF), which is about 98 percent of average. In comparison to Water Year 2015, the observed Sacramento River Region unimpaired runoff through August 31, 2015 was about 9.0 MAF, or about 50 percent of average.
 
Northern Sierra 8-Station Precipitation Index
On August 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 57.8 inches, which is about 118 percent of the seasonal average to date and 116 percent of an average water year (50.0 inches). During August, the total precipitation for the 8-Stations was 0.0 inches. Last year on August 31, the Water Year 2015 seasonal total for the 8-Stations was 36.8 inches, or about 75 percent of average.
 
San Joaquin 5-Station Precipitation Index
On August 31, the San Joaquin 5-Station Precipitation Index Water Year total was 40.0 inches, which is about 100 percent of the seasonal average to date and 98 percent of an average water year (40.8 inches). During August, the total precipitation for the 5-Stations was 0.0 inches. Last year on August 31, the Water Year 2015 seasonal total for the 5-Stations was 18.8 inches, or about 47 percent of average.
 
Tulare Basin 6-Station Precipitation Index
On August 31, the Tulare Basin 6-Station Precipitation Index Water Year total was 25.8 inches, which is about 90 percent of the seasonal average to date and 88 percent of an average water year (29.3 inches). During August, the total precipitation for the 6-Stations was 0.0 inches. Last year on August 31, the Water Year 2015 seasonal total for the 6-Stations was 13.4 inches, or about 47 percent of average.
 
Long-Range Weather Forecast
The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for September 2016, issued August 31, 2016, suggests average precipitation for all of California, except for the northernmost portion of the State, where below average precipitation is indicated.
 
Next Update
Updates to the Executive Summary will generally be issued 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 Friday, October 14, 2016, for conditions on September 30, unless there are significant hydrologic changes.

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