Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (05/31/2016)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2015): 56.87      
Average to Date: 47.60      
Percent of Average to Date: 119 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 114 %  

(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 2.30                   33                   8                  
Central Sierra 3.00                   28                   10                  
Southern Sierra 2.10                   20                   8                  
Statewide 2.50                   27                   9                  

(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)2,521       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 05/31/2016 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 1,380   2,114   65   2,448   56   ---      
Shasta Lake Sacramento 4,167   3,901   107   4,552   92   -385      
Lake Oroville Feather 3,307   2,990   111   3,538   93   -231      
New Bullards Bar Res Yuba 901   837   108   966   93   -65      
Folsom Lake American 826   821   101   977   85   -151      
New Melones Res Stanislaus 624   1,519   41   2,400   26   -1,796      
Don Pedro Res Tuolumne 1,534   1,553   99   2,030   76   -478      
Lake McClure Merced 585   701   84   1,025   57   -275      
Millerton Lake San Joaquin 360   403   89   520   69   -160      
Pine Flat Res Kings 629   722   87   1,000   63   -276      
Isabella Kern 134   299   45   568   24   -227      
San Luis Res (Offstream) 677   1,617   42   2,041   33   ---      

(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 05/31/2016

Station
Oct 1 to Date
2015 - 2016
%
Average
Season to Date
2014 - 2015
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta38.569433.558288
Eureka43.6111329.8678108
Redding36.0510922.5168104
South Lake Tahoe22.0412111.6564108
Sacramento Executive Airport16.149015.378687
Santa Rosa (Sonoma Co AP)30.318522.256384
San Francisco22.129517.437594
Stockton16.6012110.5877118
Yosemite35.569915.644394
Monterey21.5313714.5192134
Paso Robles7.37598.216658
Fresno14.271296.4258124
Bakersfield5.44875.298484
Death Valley1.61851.055568
Los Angeles6.35448.395843
Riverside5.17434.834142
Palm Springs2.50532.194644
San Diego7.73778.738775
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 May 31)
As of May 31, statewide hydrologic conditions were as follows: precipitation, 110 percent of average to date; runoff, 100 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 May 31, 2016 was about 15.7 million acre-feet (MAF), which is about 100 percent of average. In comparison to Water Year 2015, the observed Sacramento River Region unimpaired runoff through May 31, 2015 was about 8.0 MAF, or about 51 percent of average.
 
Northern Sierra 8-Station Precipitation Index
On May 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 56.9 inches, which is about 120 percent of the seasonal average to date and 114 percent of an average water year (50.0 inches). During May, the total precipitation for the 8-Stations was 2.2 inches, or about 105 percent of average for the month. Last year on May 31, the Water Year 2015 seasonal total for the 8-Stations was 35.2 inches, or about 74 percent of average.
 
San Joaquin 5-Station Precipitation Index
On May 31, the San Joaquin 5-Station Precipitation Index Water Year total was 39.7 inches, which is about 102 percent of the seasonal average to date and 97 percent of an average water year (40.8 inches). During May, the total precipitation for the 5-Stations was 1.1 inches, or about 61 percent of average for the month. Last year on May 31, the Water Year 2015 seasonal total for the 5-Stations was 17.4 inches, or about 45 percent of average.
 
Tulare Basin 6-Station Precipitation Index
On May 31, the Tulare Basin 6-Station Precipitation Index Water Year total was 25.6 inches, which is about 91 percent of the seasonal average to date and 87 percent of an average water year (29.3 inches). During May, the total precipitation for the 6-Stations was 0.4 inches, or about 36 percent of average for the month. Last year on May 31, the Water Year 2015 seasonal total for the 6-Stations was 12.1 inches, or about 43 percent of average.
 
Long-Range Weather Forecast
The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for June 2016, issued May 31, 2016, suggests average precipitation for all of California.
 
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, July 15, 2016, for conditions on July 1, unless there are significant hydrologic changes.

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