Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (12/01/2014)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2014): 7.09      
Average to Date: 9.30      
Percent of Average to Date: 76 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 14 %  

(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 0.80                   19                   3                  
Central Sierra 1.00                   18                   3                  
Southern Sierra 0.80                   21                   3                  
Statewide 0.90                   19                   3                  

(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 November (in 1000 AF)460       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%5.6       Dry
Sacramento Valley Water Year Type Index (40-30-30) @ 90%3.5       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%2.0       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 11/30/2014 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 562   1,587   35   2,448   23   ---      
Shasta Lake Sacramento 1,048   2,705   39   4,552   23   -2,204      
Lake Oroville Feather 910   2,138   43   3,538   26   -2,253      
New Bullards Bar Res Yuba 390   529   74   970   40   -406      
Folsom Lake American 278   468   59   977   28   -299      
New Melones Res Stanislaus 513   1,355   38   2,400   21   -1,457      
Don Pedro Res Tuolumne 756   1,320   57   2,030   37   -934      
Lake McClure Merced 77   450   17   1,032   7   -598      
Millerton Lake San Joaquin 175   219   80   520   34   -260      
Pine Flat Res Kings 119   371   32   1,000   12   -406      
Isabella Kern 45   156   29   568   8   -125      
San Luis Res (Offstream) 489   1,225   40   2,041   24   ---      

(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 11/30/2014
  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 11.70               131       4.56               51       29                  
Redding 9.19               123       3.12               42       27                  
Sacramento 2.23               66       1.47               44       12                  
San Francisco 2.91               64       1.69               37       12                  
Fresno 1.09               58       0.58               31       9                  
Bakersfield 0.66               62       0.97               92       10                  
Los Angeles 0.85               43       0.74               38       7                  
San Diego 0.45               25       1.78               100       4                  

  

Comments
**************************************************************************************************************************** As of December 10, 2014, a major storm, the strongest in several years, is forecasted reach California late today and last into Friday. Widespread, heavy rainfall is expected, along with significant snowfall accumulation in the Sierra. Strong, gusty winds are expected at times. Many stream gages are expected to reach Monitor Stage or Flood Stage. Several weirs on the Sacramento River are expected to flow. ***************************************************************************************************************************** As of November 30, statewide hydrologic conditions were as follows: precipitation, 70 percent of average to date; runoff, 50 percent of average to date; and reservoir storage, 55 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2015, observed through November 30, 2014 was about 0.8 million acre-feet (MAF), which is about 56 percent of average. In comparison to Water Year 2014, the observed Sacramento River Region unimpaired runoff through November 30, 2013 was about 0.7 MAF, or about 49 percent of average. On November 30, the Northern Sierra 8-Station Precipitation Index Water Year total was 7.6 inches, which is about 82 percent of the seasonal average to date and 15 percent of an average water year (50.0 inches). During November, the total precipitation for the 8-Stations was 3.9 inches, or about 62 percent of average for the month. Last year on November 30, the Water Year 2013 seasonal total for the 8-Stations was 2.4 inches, or about 25 percent of average. On November 30, the San Joaquin 5-Station Precipitation Index Water Year total was 3.3 inches, which is about 47 percent of the seasonal average to date and 8 percent of an average water year (40.8 inches). During November, the total precipitation for the 5-Stations was 3.1 inches, or about 66 percent of average for the month. Last year on November 30, the Water Year 2013 seasonal total for the 5-Stations was 1.9 inches, or about 27 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for December 2014, issued November 30, 2014, suggests above average rainfall for all of California. 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, January 12, 2015, for conditions on December 1, unless there are significant hydrologic changes.


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