Executive Update: Hydrologic Conditions in California

Executive Update

Hydrologic Conditions in California (04/17/2014)

Northern Sierra Precipitation Accumulation (1)
Rainfall & Snow Water Content (in inches)
 
Water Year Amount to Date (since Oct. 1, 2013): 26.70      
Average to Date: 43.70      
Percent of Average to Date: 61 %  
Average for the Water Year (Oct. 1 through Sep. 30) 50.00      
Percent of Average for the Water Year (Oct. 1 through Sep. 30) 53 %  

(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 3.80                   14                   13                  
Central Sierra 8.50                   31                   29                  
Southern Sierra 5.50                   22                   21                  
Statewide 6.30                   24                   22                  

(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 March (in 1000 AF)2,053       n/a
Sacramento Valley Water Year Type Index (40-30-30) @ 50%4.1       Critical
Sacramento Valley Water Year Type Index (40-30-30) @ 90%3.8       Critical
San Joaquin Valley Water Year Type Index (60-20-20) @ 50%1.3       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 04/16/2014 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 1,311   1,976   66   2,448   54   ---      
Shasta Lake Sacramento 2,390   3,815   63   4,552   53   -2,162      
Lake Oroville Feather 1,839   2,792   66   3,538   52   -1,362      
New Bullards Bar Res Yuba 657   736   89   966   68   -193      
Folsom Lake American 517   682   76   977   53   -222      
New Melones Res Stanislaus 1,003   1,507   67   2,420   41   -1,136      
Don Pedro Res Tuolumne 1,096   1,485   74   2,030   54   -594      
Lake McClure Merced 260   587   44   1,025   25   -536      
Millerton Lake San Joaquin 172   366   47   520   33   -348      
Pine Flat Res Kings 254   590   43   1,000   25   -705      
Isabella Kern 61   217   28   568   11   -301      
San Luis Res (Offstream) 945   1,833   52   2,039   46   ---      

(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 04/16/2014
  Jul 1 to Date
2013 - 2014
(in inches)
%
Avg
Jul 1 to Date
2012 - 2013
(in inches)
%
Avg
% Avg
Jul 1 to Jun 30
2013 - 2014
Eureka 19.07               52       30.71               84       47                  
Redding 17.53               57       26.02               84       51                  
Sacramento 9.34               54       14.68               85       50                  
San Francisco 12.18               55       16.42               74       52                  
Fresno 4.15               40       5.60               53       36                  
Bakersfield 2.01               33       3.10               51       31                  
Los Angeles 4.36               36       6.50               53       34                  
San Diego 4.89               49       6.24               63       47                  

  

Comments
SOME VALUES IN THIS PRODUCT ARE MONTHLY VALUES AND ARE ONLY UPDATED AT THE BEGINNING OF EACH MONTH. WEEKLY RUNOFF FORECAST UPDATES HAVE BEEN ADDED TO THE COMMENT SECTION. The April 15, 2014 Bulletin 120 (B120) forecast update has been posted. The forecasts include observed conditions through the morning of April 15, 2014 and are posted at http://cdec.water.ca.gov/cgi-progs/iodir?s=b120up. Considering the rivers forecasted in the B120 update, the projected median April-July runoff in the major Sierra river basins ranges from 11 percent on the Tule River to 50 percent for the Inflow to Shasta Lake. On average, the forecasts dropped 3 percent from the April 8 forecast. The forecasts in the Sacramento, San Joaquin, and Tulare hydrologic regions dropped 4, 3, and 2 percent, respectively. The largest drops (approximately 5 percent) were forecast on the Yuba and Mokelumne Rivers. As of March 31, statewide hydrologic conditions were as follows: precipitation, 50 percent of average to date; runoff, 35 percent of average to date; snow water equivalent, 25 percent of average for the date (25 percent of the April 1 average); and reservoir storage, 70 percent of average for the date. Sacramento River Region unimpaired runoff, for Water Year 2014, observed through March 31, 2014 was about 4.3 million acre-feet (MAF), which is about 39 percent of average. In comparison to Water Year 2014, the observed Sacramento River Region unimpaired runoff through March 31, 2013 was about 8.2 MAF, or about 75 percent of average. On March 31, the Northern Sierra 8-Station Precipitation Index Water Year total was 26.1 inches, which is about 63 percent of the seasonal average to date and 52 percent of an average water year (50.0 inches). During March, the total precipitation for the 8-Stations was 10.0 inches, or about 145 percent of average for the month. Last year on March 31, the Water Year 2013 seasonal total for the 8-Stations was 39.5 inches, or about 95 percent of average. On March 31, the San Joaquin 5-Station Precipitation Index Water Year total was 15.0 inches, which is about 45 percent of the seasonal average to date and 37 percent of an average water year (40.8 inches). During March, the total precipitation for the 5-Stations was 4.7 inches, or about 77 percent of average for the month. Last year on March 31, the Water Year 2013 seasonal total for the 5-Stations was 23.9 inches, or about 71 percent of average. The latest National Weather Service Climate Prediction Center (CPC) long-range, 1-month precipitation outlook for May 2014, issued April 17, 2014, suggests average rainfall for most of California, except the extreme northwestern portion of the State, where below average precipitation is indicated. 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, April 24, 2014, for conditions as of April 22, unless there are significant hydrologic changes.


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