California’s Water Year 2014 (October 1, 2013 through September 30, 2014) has been one of the driest in decades and follows two consecutive dry years throughout the state. In most years, California receives about half of its precipitation in the months of December, January and February, with much of that precipitation falling as snow in the Sierras. Only a handful of large winter storms can make the difference between a wet year and a dry one.
In normal years, the snowpack stores water during the winter months and releases it through melting in the spring and summer to replenish rivers and reservoirs. However, relatively dry weather conditions this year have reduced the amount of snowpack in California’s mountains. Each of this season’s first three snow surveys – conducted in early January, late January and late February – found a statewide snowpack water equivalent (WEQ) far below average for the dates of the surveys. On February 27, the WEQ was only 24 percent of the statewide average for the date.
Rainfall precipitation also has been far below normal during this water year as recorded by stations throughout the Sierras. The eight stations in the Northern Sierra recorded little more than 15 inches from October through February, or only 44 percent of the seasonal average of about 35 inches during that period. The five stations in the San Joaquin region had similar readings; the 10 inches of rain that fell on those stations from October through February was 37 percent of the seasonable average of 27.5 inches.
DWR’s late November experimental seasonal forecast for the water year saw mostly dry conditions for the state, and so far, the forecast has been accurate, but Mother Nature may surprise us yet. About half of the years with similarly dry first quarters in the historical record of northern Sierra precipitation, for example, caught up to average by the end of the season. However, a normal precipitation year would not be enough to overcome low soil moisture and water storage conditions; many water users would need a wet year to be made whole.
The conditions for the major reservoirs in California: http://cdec.water.ca.gov/cdecapp/resapp/getResGraphsMain.action
For background on droughts in California and answers to frequently asked questions, see the column below.
Processed satellite imagery of a portion of the San Joaquin Valley showing the difference in the NDVI between August 2011 (wet year) and August 2013 (dry year). The Tulare Lake bed is just right of center at the bottom of the image. NDVI is the Normalized Difference Vegetation Index, a measure of vegetation conditions that can also be used to show drought or water shortage impacts in irrigated areas. Image courtesy of Lee Johnson, CSU Monterey Bay.
Current Water Conditions
- • ACWA Launches Interactive Map Showing Local Response Actions
- • Cal OES Drought Page
- • Governor’s letter, Interagency Drought Task Force
- • DWR-CSUF Agricultural Drought Preparedness Workshop
- • Experimental Seasonal Forecast
- • Experimental Seasonal Forecast Presentation
- • DWR-NWRI drought workshop for urban water agencies, October 2013
- • DWR-WSWC workshop on drought impacts, August 2013
- • DWR-WSWC workshop on improving drought prediction, April 2013