Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (01/01/2015)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2014): 22.79      
Average to Date: 17.70      
Percent of Average to Date: 129 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 46 %  

(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 5.80                   56                   20                  
Central Sierra 4.70                   44                   16                  
Southern Sierra 3.90                   47                   15                  
Statewide 4.80                   49                   17                  

(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 December (in 1000 AF)2,910       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%6.7       Below Normal
Sacramento Valley Water Year Type Index (40-30-30) @ 90%4.9       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%2.1       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%1.4       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 12/31/2014 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 815   1,642   50   2,448   33   ---      
Shasta Lake Sacramento 1,867   2,828   66   4,552   41   -1,466      
Lake Oroville Feather 1,347   2,174   62   3,538   38   -1,553      
New Bullards Bar Res Yuba 485   546   89   970   50   -311      
Folsom Lake American 430   476   90   977   44   -147      
New Melones Res Stanislaus 547   1,382   40   2,400   23   -1,423      
Don Pedro Res Tuolumne 794   1,339   59   2,030   39   -896      
Lake McClure Merced 73   452   16   1,032   7   -601      
Millerton Lake San Joaquin 180   271   66   520   35   -255      
Pine Flat Res Kings 130   408   32   1,000   13   -395      
Isabella Kern 45   159   28   568   8   -125      
San Luis Res (Offstream) 820   1,388   59   2,041   40   ---      

(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.

Selected Cities Precipitation Accumulation As of 12/31/2014
  Jul 1 to Date
2014 - 2015
(in inches)
%
Avg
Jul 1 to Date
2013 - 2014
(in inches)
%
Avg
% Avg
Jul 1 to Jun 30
2014 - 2015
Eureka 21.51               126       5.12               30       53                  
Redding 19.69               143       3.50               25       57                  
Sacramento 10.85               164       1.90               29       59                  
San Francisco 15.09               166       2.08               23       64                  
Fresno 3.38               92       0.73               20       29                  
Bakersfield 2.68               129       1.07               51       41                  
Los Angeles 4.89               122       1.04               26       38                  
San Diego 4.95               150       2.24               68       48                  

  

Comments
As of December 31, statewide hydrologic conditions were as follows: precipitation, 110 percent of average to date; runoff, 105 percent of average to date; snow water content, 50 percent of average to date (15 percent of the April 1 average); and reservoir storage, 65 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2015, observed through December 31, 2014 was about 3.6 million acre-feet (MAF), which is about 115 percent of average. In comparison to Water Year 2014, the observed Sacramento River Region unimpaired runoff through December 31, 2013 was about 1.0 MAF, or about 33 percent of average. On December 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 22.8 inches, which is about 129 percent of the seasonal average to date and 46 percent of an average water year (50.0 inches). During December, the total precipitation for the 8-Stations was 15.2 inches, or about 181 percent of average for the month. Last year on December 31, the Water Year 2014 seasonal total for the 8-Stations was 3.3 inches, or about 19 percent of average. On December 31, the San Joaquin 5-Station Precipitation Index Water Year total was 9.1 inches, which is about 69 percent of the seasonal average to date and 22 percent of an average water year (40.8 inches). During December, the total precipitation for the 5-Stations was 5.9 inches, or about 95 percent of average for the month. Last year on December 31, the Water Year 2014 seasonal total for the 5-Stations was 3.0 inches, or about 23 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for January 2015, issued December 31, 2014, suggests above average rainfall for Southern California. Central and most of Northern California are shown as having equal chances of wet or dry conditions. For the extreme northeastern portion of the State, 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 Thursday, February 12, 2015, for conditions on February 1, unless there are significant hydrologic changes.


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