Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (04/30/2016)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2015): 54.67      
Average to Date: 45.50      
Percent of Average to Date: 120 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 109 %  

(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 13.00                   62                   46                  
Central Sierra 16.50                   69                   57                  
Southern Sierra 10.30                   47                   38                  
Statewide 13.70                   61                   49                  

(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 April (in 1000 AF)2,920       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 04/30/2016 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 1,494   2,020   74   2,448   61   ---      
Shasta Lake Sacramento 4,233   3,924   108   4,552   93   -319      
Lake Oroville Feather 3,400   2,877   118   3,538   96   0      
New Bullards Bar Res Yuba 881   767   115   966   91   -18      
Folsom Lake American 826   729   113   977   85   18      
New Melones Res Stanislaus 622   1,505   41   2,400   26   -1,610      
Don Pedro Res Tuolumne 1,365   1,487   92   2,030   67   -362      
Lake McClure Merced 480   607   79   1,025   47   -253      
Millerton Lake San Joaquin 295   366   81   520   57   -226      
Pine Flat Res Kings 520   613   85   1,000   52   -402      
Isabella Kern 88   231   38   568   16   -273      
San Luis Res (Offstream) 957   1,822   53   2,041   47   ---      

(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 04/30/2016

Station
Oct 1 to Date
2015 - 2016
%
Average
Season to Date
2014 - 2015
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta37.389731.958386
Eureka43.2011829.8581107
Redding35.1011322.1771101
South Lake Tahoe19.971179.645698
Sacramento Executive Airport15.759115.308985
Santa Rosa (Sonoma Co AP)30.018822.246583
San Francisco21.979817.347793
Stockton16.2512410.5781116
Yosemite35.0210214.294292
Monterey21.2513914.2193132
Paso Robles7.37618.136758
Fresno13.981315.8555122
Bakersfield4.89804.617676
Death Valley1.61861.055668
Los Angeles6.30447.465242
Riverside4.99434.233740
Palm Springs2.48542.074543
San Diego7.29736.536671
Updated Information and Data
Daily Drought Information Summary
Daily Statewide Hydrologic Update(Interactive)
Weekly Update to Unimpaired Runoff Forecast (Feb - Jun)
Unimpaired Forecast Discussion
Bulletin 120, Water Conditions in California (Monthly, Feb - May)
Comments
 
Statewide Hydrologic Conditions (As of April 30)
As of April 30, statewide hydrologic conditions were as follows: precipitation, 105 percent of average to date; snow water content, 55 percent of average to date (40 percent of the April 1 average); runoff, 110 percent of average to date; and reservoir storage, 90 percent of average for the date.
 
Sacramento River Unimpaired Runoff
Sacramento River Region unimpaired runoff, for Water Year 2016, observed through April 30, 2016 was about 14.2 million acre-feet (MAF), which is about 106 percent of average. In comparison to Water Year 2015, the observed Sacramento River Region unimpaired runoff through April 30, 2015 was about 7.5 MAF, or about 56 percent of average.
 
Northern Sierra 8-Station Precipitation Index
On April 30, the Northern Sierra 8-Station Precipitation Index Water Year total was 54.7 inches, which is about 120 percent of the seasonal average to date and 109 percent of an average water year (50.0 inches). During April, the total precipitation for the 8-Stations was 2.8 inches, or about 72 percent of average for the month. Last year on April 30, the Water Year 2015 seasonal total for the 8-Stations was 34.0 inches, or about 75 percent of average.
 
San Joaquin 5-Station Precipitation Index
On April 30, the San Joaquin 5-Station Precipitation Index Water Year total was 38.7 inches, which is about 104 percent of the seasonal average to date and 95 percent of an average water year (40.8 inches). During April, the total precipitation for the 5-Stations was 2.8 inches, or about 78 percent of average for the month. Last year on April 30, the Water Year 2015 seasonal total for the 5-Stations was 16.0 inches, or about 43 percent of average.
 
Tulare Basin 6-Station Precipitation Index
On April 30, the Tulare Basin 6-Station Precipitation Index Water Year total was 25.2 inches, which is about 94 percent of the seasonal average to date and 86 percent of an average water year (29.3 inches). During April, the total precipitation for the 6-Stations was 1.6 inches, or about 61 percent of average for the month. Last year on April 30, the Water Year 2015 seasonal total for the 6-Stations was 11.2 inches, or about 42 percent of average.
 
Long-Range Weather Forecast
The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for May 2016, issued April 30, 2016, suggests above normal precipitation for almost all of California, except the north coastal region of the State where normal 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 Wednesday, June 15, 2016, for conditions on June 1, unless there are significant hydrologic changes.

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