Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (03/01/2015)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2014): 30.57      
Average to Date: 34.70      
Percent of Average to Date: 88 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 61 %  

(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 4.40                   17                   15                  
Central Sierra 5.10                   20                   17                  
Southern Sierra 4.80                   21                   18                  
Statewide 4.80                   20                   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 February (in 1000 AF)2,228       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%4.7       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%1.1       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%0.9       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 02/28/2015 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 1,147   1,816   63   2,448   47   ---      
Shasta Lake Sacramento 2,613   3,326   79   4,552   57   -1,428      
Lake Oroville Feather 1,736   2,466   70   3,538   49   -1,403      
New Bullards Bar Res Yuba 596   626   95   970   61   -200      
Folsom Lake American 564   543   104   977   58   -63      
New Melones Res Stanislaus 606   1,468   41   2,400   25   -1,364      
Don Pedro Res Tuolumne 872   1,442   60   2,030   43   -818      
Lake McClure Merced 88   534   16   1,032   8   -587      
Millerton Lake San Joaquin 195   341   57   520   38   -240      
Pine Flat Res Kings 160   530   30   1,000   16   -659      
Isabella Kern 48   184   26   568   8   -197      
San Luis Res (Offstream) 1,293   1,738   74   2,041   63   ---      

(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 03/01/2015

Station
Oct 1 to Date
2014 - 2015
%
Average
Season to Date
2013 - 2014
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta29.42996.772367
Eureka24.18868.743160
Redding19.93829.954158
South Lake Tahoe7.94609.357139
Sacramento Executive Airport13.23995.464171
Santa Rosa (Sonoma Co AP)20.727610.874057
San Francisco15.92897.494267
Stockton9.28934.494566
Yosemite10.96429.313629
Monterey13.011144.764281
Paso Robles7.68853.083460
Fresno4.53593.354439
Bakersfield4.11941.513564
Death Valley1.05720.533744
Los Angeles6.40584.203843
Riverside3.61411.251429
Palm Springs1.24320.541422
San Diego5.48743.094253
Comments
As of February 28, statewide hydrologic conditions were as follows: precipitation, 80 percent of average to date; runoff, 75 percent of average to date; snow water content, 13 percent of average to date (12 percent of the April 1 average); and reservoir storage, 70 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2015, observed through February 28, 2015 was about 6.3 million acre-feet (MAF), which is about 77 percent of average. In comparison to Water Year 2014, the observed Sacramento River Region unimpaired runoff through February 28, 2014 was about 2.5 MAF, or about 30 percent of average. On February 28, the Northern Sierra 8-Station Precipitation Index Water Year total was 30.7 inches, which is about 88 percent of the seasonal average to date and 61 percent of an average water year (50.0 inches). During February, the total precipitation for the 8-Stations was 7.6 inches, or about 95 percent of average for the month. Last year on February 28, the Water Year 2014 seasonal total for the 8-Stations was 16.0 inches, or about 46 percent of average. On February 28, the San Joaquin 5-Station Precipitation Index Water Year total was 13.3 inches, which is about 48 percent of the seasonal average to date and 33 percent of an average water year (40.8 inches). During February, the total precipitation for the 5-Stations was 4.0 inches, or about 58 percent of average for the month. Last year on February 28, the Water Year 2014 seasonal total for the 5-Stations was 10.3 inches, or about 37 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for March 2015, issued February 28, 2015, suggests equal chances of wet or dry conditions for most of California. For the northern 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 Monday, April 13, 2015, for conditions on April 1, unless there are significant hydrologic changes.


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