Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (09/01/2014)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2013): 29.71      
Average to Date: 49.10      
Percent of Average to Date: 61 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 59 %  

(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 ---                   --- (3)                   ---                  
Central Sierra ---                   --- (3)                   ---                  
Southern Sierra ---                   --- (3)                   ---                  
Statewide ---                   --- (3)                   ---                  

(2) April 1 is the date of normal maximum accumulation for the season.
(3) 'Percent Average to Date' is not calculated this early in the WY when the historical average is small.

Forecast of Regional Water Supply Indices (5)
Index Value Year Type
8 River Index for August (in 1000 AF)326       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%3.9       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%1.2       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%1.1       Critical

(4) 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 08/31/2014 midnight
Reservoir River Storage
(in 1000 AF)
Avg Storage
(in 1000 AF)
%
Average
Capacity
(in 1000 AF)
%
Capacity
Flood Control (6)
Encroachment
(in 1000 AF)
Trinity Lake Trinity 698   1,803   39   2,448   28   ---      
Shasta Lake Sacramento 1,342   2,878   47   4,552   29   -3,210      
Lake Oroville Feather 1,100   2,318   47   3,538   31   -2,438      
New Bullards Bar Res Yuba 445   653   68   970   46   -521      
Folsom Lake American 381   611   62   977   39   -596      
New Melones Res Stanislaus 553   1,387   40   2,400   23   -1,867      
Don Pedro Res Tuolumne 820   1,436   57   2,030   40   -1,210      
Lake McClure Merced 159   564   28   1,032   15   -866      
Millerton Lake San Joaquin 229   236   97   520   44   -291      
Pine Flat Res Kings 114   378   30   1,000   11   -886      
Isabella Kern 54   216   25   568   9   -278      
San Luis Res (Offstream) 380   858   44   2,041   19   ---      

(5) 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.

Selected Cities Precipitation Accumulation As of 08/31/2014
  Jul 1 to Date
2014 - 2014
(in inches)
%
Avg
Jul 1 to Date
2013 - 2013
(in inches)
%
Avg
% Avg
Jul 1 to Jun 30
2014 - 2015
Eureka 0.04               8       0.08               16       0                  
Redding 0.21               78       0.00               0       1                  
Sacramento 0.01               20       0.00               0       0                  
San Francisco 0.09               150       0.04               67       0                  
Fresno 0.01               50       0.00               0       0                  
Bakersfield 0.00               0       0.00               0       0                  
Los Angeles 0.17               213       0.03               38       1                  
San Diego 0.08               160       0.05               100       1                  

  

Comments
As of August 31, statewide hydrologic conditions were as follows: precipitation, 55 percent of average to date, runoff, 35 percent of average to date, and reservoir storage, 60 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2014, observed through August 31, 2014 was about 7.2 million acre-feet (MAF), which is about 40 percent of average. In comparison to Water Year 2013, the observed Sacramento River Region unimpaired runoff through August 31, 2013 was about 11.9 MAF, or about 66 percent of average. On August 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 29.7 inches, which is about 60 percent of the seasonal average to date and 59 percent of an average water year (50.0 inches). During August, the total precipitation for the 8-Stations was 0.6 inches, or about 200 percent of average for the month. Last year on August 31, the Water Year 2013 seasonal total for the 8-Stations was 44.4 inches, or about 90 percent of average. On August 31, the San Joaquin 5-Station Precipitation Index Water Year total was 19.6 inches, which is about 49 percent of the seasonal average to date and 48 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 2013 seasonal total for the 5-Stations was 26.2 inches, or about 65 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for September 2014, issued August 31, 2014, suggests no tendency for above or below average rainfall for most of California. The exceptions are the extreme northern part of the State where below normal precipitation is indicated, and the extreme southeastern portion of the State where above normal precipitation is indicated. 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, October 13, 2014, for conditions on October 1, unless there are significant hydrologic changes.


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