Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (02/01/2015)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2014): 23.07      
Average to Date: 26.70      
Percent of Average to Date: 86 %  
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 4.40                   24                   15                  
Central Sierra 4.50                   24                   15                  
Southern Sierra 3.90                   26                   15                  
Statewide 4.30                   25                   15                  

(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 January (in 1000 AF)810       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%5.1       Critical
Sacramento Valley Water Year Type Index (40-30-30) @ 90%3.7       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%1.5       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%1.1       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 01/31/2015 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 874   1,730   50   2,448   36   ---      
Shasta Lake Sacramento 2,001   3,072   65   4,552   44   -1,805      
Lake Oroville Feather 1,444   2,317   62   3,538   41   -1,718      
New Bullards Bar Res Yuba 503   584   86   970   52   -293      
Folsom Lake American 448   508   88   977   46   -129      
New Melones Res Stanislaus 563   1,423   40   2,400   23   -1,407      
Don Pedro Res Tuolumne 827   1,391   59   2,030   41   -863      
Lake McClure Merced 64   489   13   1,032   6   -610      
Millerton Lake San Joaquin 186   333   56   520   36   -249      
Pine Flat Res Kings 132   470   28   1,000   13   -393      
Isabella Kern 45   173   26   568   8   -125      
San Luis Res (Offstream) 1,103   1,607   69   2,041   54   ---      

(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 02/01/2015

Station
Oct 1 to Date
-
%
Average
Season to Date
-
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta19.67881.01545
Eureka19.14853.031347
Redding16.55882.531348
South Lake Tahoe3.89373.513319
Sacramento Executive Airport10.411051.461556
Santa Rosa (Sonoma Co AP)16.52791.58846
San Francisco14.451081.711361
Stockton7.841051.652256
Yosemite7.81415.012621
Monterey11.761411.111373
Paso Robles5.96930.46747
Fresno3.40601.292330
Bakersfield3.361081.193852
Death Valley0.79840.323433
Los Angeles5.71800.881238
Riverside2.88500.981723
Palm Springs1.07380.17619
San Diego5.301042.204351
Comments
As of January 31, statewide hydrologic conditions were as follows: precipitation, 80 percent of average to date; runoff, 65 percent of average to date; snow water content, 20 percent of average to date (10 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 January 31, 2015 was about 4.3 million acre-feet (MAF), which is about 76 percent of average. In comparison to Water Year 2014, the observed Sacramento River Region unimpaired runoff through January 31, 2014 was about 1.4 MAF, or about 24 percent of average. On January 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 23.1 inches, which is about 87 percent of the seasonal average to date and 46 percent of an average water year (50.0 inches). During January, the total precipitation for the 8-Stations was 0.3 inches, or about 3 percent of average for the month. Last year on January 31, the Water Year 2014 seasonal total for the 8-Stations was 4.5 inches, or about 17 percent of average. On January 31, the San Joaquin 5-Station Precipitation Index Water Year total was 9.3 inches, which is about 45 percent of the seasonal average to date and 23 percent of an average water year (40.8 inches). During January, the total precipitation for the 5-Stations was 0.2 inches, or about 3 percent of average for the month. Last year on January 31, the Water Year 2014 seasonal total for the 5-Stations was 4.5 inches, or about 22 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for February 2015, issued January 31, 2015, suggests equal chances of wet or dry conditions for most of California. For the northwestern portion of the State, above 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, March 12, 2015, for conditions on March 1, unless there are significant hydrologic changes.


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