As California experiences a second consecutive dry year, last week the California Department of Water Resources announced an adjustment to its initial State Water Project allocation for the 2021 water year. The department now expects to deliver 5% of requested supplies this year, down from the initial allocation of 10% announced in December.

The State Water Project is a water management project and one of the largest public water and power utilities in the world, providing drinking water for more than 23 million people and generating an average of 6,500 GWh of hydroelectricity annually.

The SWP collects water from rivers in Northern California and redistributes it to water-scarce but populous cities through a network of aqueducts, pumping stations and power plants. About 70% of the water provided by the project is used for urban areas and industry in Southern California and the San Francisco Bay Area and 30% is used for irrigation in the Central Valley.

Yearly allocations are based on conservative assumptions regarding hydrology and factors such as reservoir storage. Allocations are reviewed monthly and may change based on snowpack and runoff information. They are typically finalized by May.

“We are now facing the reality that it will be a second dry year for California and that is having a significant impact on our water supply,” said DWR Director Karla Nemeth. “The Department of Water Resources is working with our federal and state partners to plan for the impacts of limited water supplies this summer for agriculture as well as urban and rural water users. We encourage everyone to look for ways to use water efficiently in their everyday lives.”

Ongoing drought conditions require the coordination of federal, state and local agencies. The U.S. Bureau of Reclamation, which operates the Central Valley Project, is also expected to adjust its initial CVP water supply allocation.

Last week the State Water Resources Control Board mailed early warning notices to approximately 40,000 water right holders urging them to plan for potential shortages by reducing water use and adopting practical conservation measures.

As a result of the persistent drought conditions, and in accordance with its permit for the long-term operation of the State Water Project, DWR has submitted a revised drought contingency plan to the California Department of Fish and Wildlife. The plan provides updated hydrologic conditions and outlines areas of concern for the joint operations of the SWP and the CVP, water quality and environmental impacts.

DWR does not anticipate the need to pursue a temporary urgency change petition to allow for temporary changes to the water quality and outflow requirements for the Sacramento-San Joaquin Delta.

The severity of the situation is particularly evident in the north state. Lake Oroville is currently at 53% of average. The Feather River watershed, which feeds into Lake Oroville, has seen significantly less precipitation this year than normal, on track for its second driest year on record. Following a below-average 2020 water year, California’s major reservoirs are at 50% of capacity.

Following the 2012-16 drought DWR officials enacted many programs focused on managing the state’s water through a strategic, integrated approach with a strong emphasis on water use efficiency and conservation. The state provides assistance and tools to local water agencies to help them reduce their drought vulnerability. DWR’s water use and efficiency branch provides agencies and individuals assistance for improving water use efficiency and developing and meeting efficient water use requirements.

The­­ 5% allocation amounts to 210,266 acre-feet of water distributed among the 29 long-term SWP contractors who serve more than 27 million Californians and 750,000 acres of farmland.

Allocations represent the amount of SWP water DWR will deliver for the year and are reviewed monthly based on several factors, such as water in storage, environmental requirements and rain and snow runoff projections. For 2020 the initial SWP allocation was 10% and the final allocation was 20% in May.

Source: California Department of Water Resources