Update From the Pacific Institute California Drought Response Group – April 18


For the latest updates about the California drought go to www.californiadrought.org

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This week in… Groundwater

Groundwater has been on the lips (both literally and metaphorically) of Californians since the drought began. During normal years, groundwater use accounts for about 40% of total water use in the state and can increase up to 60% or more during dry years. This has resulted in groundwater levels that have been steadily declining since the early 1960s and these levels have yet to totally rebound, indicating unsustainable use (see figure below). 

cumulative groundwater losses-4-18

Cumulative groundwater losses (cubic km and million acre-ft) in California’s Central Valley since 1962.
Source: UCCHM

In the current drought, farmers and residents are already drilling more and deeper wells. In some counties, new drilling permit applications are more than double (in some areas quadruple) what they were this time last year.

State regulators, water managers, and other decision makers have been taking notice. Yesterday, California state agencies held a workshop to discuss proposed solutions to implementing improved groundwater management. At the workshop, several organizations – including the Association of California Water Agencies, The National Heritage Institute, the Planning and Conservation League, the Valley AG Water Coalition, and the California Water Foundation – gave presentations outlining their solutions. These proposals generally agreed that the state’s focus should be on enabling improvement of local or regional management of groundwater. Plans also noted the importance of defining “sustainable” management; improving data collection and monitoring; identifying a reliable source of funding for improvement projects; and increasing the use and effectiveness of groundwater management plans.

Below is the April 18th update of the key information and graphics on the status of the current drought. Much of this information can be found at our California Drought website: www.californiadrought.org.

California Drought Status

Seasonal Drought Outlook

According to the US Drought Monitor, California drought conditions have not changed since last week, with more than 95% of the state still experiencing moderate to exceptional drought conditions and 100% of the state in some form of abnormally dry circumstances. Yesterday, the National Weather Service’s Climate Prediction Center issued their monthly Seasonal Drought Outlook for April 17th through July 31st. The map indicates that California can expect the drought to persist or intensify during this period. In addition, the outlook shows that most of Oregon, Nevada, Arizona, and New Mexico can also expect the current drought to persist or intensify. Other states with large areas that are also expected to continue to be affected include Utah, Idaho, Washington, Oklahoma, Texas, Kansas, and Colorado.



We have effectively come to the end of the rainy season, and so it is unlikely that we will see any significant change in precipitation until October.

This map from NOAA’s Climate Data Center shows the precipitation deficit since the start of California’s water year on October 1st through April 17th.

Other than a few, small area of precipitation in the north, California received effectively no precipitation this week.



California snowpack is currently at about 19% of the April 1st average, down from 30% last week. According to the US Drought Monitor, much of the snowmelt was a result of abnormally high temperatures in the west, with California temperatures 9-12 degrees Fahrenheit above normal. Some areas lost half of the snow water equivalence in a single week. This is an extremely rapid drop and indicative of the rate at which the current drought will worsen in the coming dry months.


Reservoir Conditions

Statewide, California reservoirs are still at about 49% of total capacity and about 66% of the historical average. This Department of Water Resources graphic shows the levels of most of the state’s largest reservoirs’ levels as a percent of capacity and historical average. 


Soil Moisture

California soil moisture has not changed much in the past week, with particularly dry areas in Northern California and the Los Angeles area.