Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (01/01/2016)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2015): 16.68      
Average to Date: 17.70      
Percent of Average to Date: 94 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 33 %  

(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 10.90                   106                   38                  
Central Sierra 12.30                   117                   42                  
Southern Sierra 7.10                   84                   27                  
Statewide 10.30                   106                   37                  

(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)1,250       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%5.8       Dry
Sacramento Valley Water Year Type Index (40-30-30) @ 90%4.1       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%2.4       Dry
San Joaquin Valley Water Year Type Index (60-20-20) @ 75%1.9       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 12/31/2015 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 497   1,642   30   2,448   20   ---      
Shasta Lake Sacramento 1,427   2,828   50   4,552   31   -1,944      
Lake Oroville Feather 1,017   2,174   47   3,538   29   -2,007      
New Bullards Bar Res Yuba 395   546   72   966   41   -401      
Folsom Lake American 239   476   50   977   24   -338      
New Melones Res Stanislaus 310   1,382   22   2,400   13   -1,660      
Don Pedro Res Tuolumne 707   1,339   53   2,030   35   -983      
Lake McClure Merced 88   452   19   1,025   9   -587      
Millerton Lake San Joaquin 177   271   65   520   34   -258      
Pine Flat Res Kings 151   408   37   1,000   15   -530      
Isabella Kern 33   159   21   568   6   -137      
San Luis Res (Offstream) 436   1,388   31   2,041   21   ---      

(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 01/01/2016

Station
Oct 1 to Date
2015 - 2016
%
Average
Season to Date
2014 - 2015
%
Average
% Average
Oct 1 - Sep 30
Mount Shasta8.965919.2212721
Eureka20.0812617.8411250
Redding9.837616.2912728
South Lake Tahoe8.121023.794840
Sacramento Executive Airport3.445510.4116619
Santa Rosa (Sonoma Co AP)7.315316.4211920
San Francisco6.617514.4516328
Stockton4.59977.8416633
Yosemite13.401077.746235
Monterey7.6214811.7622847
Paso Robles1.99545.7215616
Fresno5.191503.199245
Bakersfield1.33682.6713621
Death Valley1.081960.539646
Los Angeles1.02254.621157
Riverside1.12402.30829
Palm Springs0.1790.87473
San Diego2.85924.8715728
Comments
As of December 31, statewide hydrologic conditions were as follows: precipitation, 100 percent of average to date; snow water content, 105 percent of average to date (35 percent of the April 1 average); runoff, 60 percent of average to date; and reservoir storage, 55 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2016, observed through December 31, 2015 was about 1.7 million acre-feet (MAF), which is about 53 percent of average. In comparison to Water Year 2015, the observed Sacramento River Region unimpaired runoff through December 31, 2014 was about 3.6 MAF, or about 115 percent of average. On December 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 16.7 inches, which is about 94 percent of the seasonal average to date and 33 percent of an average water year (50.0 inches). During December, the total precipitation for the 8-Stations was 11.8 inches, or about 140 percent of average for the month. Last year on December 31, the Water Year 2015 seasonal total for the 8-Stations was 22.8 inches, or about 129 percent of average. On December 31, the San Joaquin 5-Station Precipitation Index Water Year total was 15.7 inches, which is about 120 percent of the seasonal average to date and 38 percent of an average water year (40.8 inches). During December, the total precipitation for the 5-Stations was 8.8 inches or about 142 percent of average for the month. Last year on December 31, the Water Year 2015 seasonal total for the 5-Stations was 9.1 inches, or about 69 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for January 2016, issued December 31, 2015, suggests above normal precipitation for almost all of California, except for the extreme northern region of the State where equal chances of wet or dry conditions are 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 Tuesday, February 16, 2016, for conditions on February 1, unless there are significant hydrologic changes.


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