Friday, May 17, 2024

CA State Water Project limits initial water allocation to health, safety needs

O'Neill Forebay San Luis Reservoir
Flying over the O’Neill Forebay that’s part of San Luis Reservoir in early October 2021 — photo by Vicky Boyd

The California Department of Water Resources plans to make no regular water deliveries from the State Water Project for 2022. In its Dec. 1 announcement, the state said it would only release water needed for health and safety uses.

It marks the first time since 2014, when the state was in the midst of another drought, that DWR has made a 0% water allocation.

This comes in anticipation of a third dry year with reservoirs at or near historic lows. Should the state receive above-normal precipitation for the remainder of the water year, DWR could change the allocations.

The State Water Project serves about 27 million people through 29 water agencies that contract to receive supplies. DWR has advised them to expect an initial allocation that prioritizes health and safety water needs.

Among the larger State Water Project reservoirs are Lake Oroville in the northern Sacramento River Valley and San Luis Reservoir located on the edge of the Central Valley southeast of San Jose.

Changing typical allocation process

In its announcement, the department said the State Water Project would not be planning water deliveries through its typical allocation process until the state has a clearer picture of the hydrologic and reservoir conditions going into the spring.

DWR is focused on prioritizing water supply in four categories: water for health and safety needs and Delta salinity control; water for endangered species; water to reserve in storage; and water for additional supply allocations if the hydrology allows.

“Despite a wet start to the water year, conditions have dried out since that first storm and we are still planning for a below-average water year. That means we need to prepare now for a dry winter and severe drought conditions to continue through 2022,” said DWR Director Karla Nemeth. “We will be working with our federal partners and SWP contractors to take a conservative planning approach to balance limited water supplies with the needs of residents, businesses, and the environment.”

In addition to limiting the initial allocation to health and safety needs, DWR is making plans to adjust State Water Project operations this winter and spring. DWR is capturing and storing water when possible in Lake Oroville and south of the Delta in San Luis Reservoir to increase available supplies for 2022. It will continue to do so throughout the winter.

Health and safety demands for the Bay Area and central and Southern California will be met with water available from the Sacramento-San Joaquin Delta as well as water stored in San Luis Reservoir.

Maintaining water for health and safety

Water in Lake Oroville will be reserved to maintain Delta water quality, protect endangered species and meet senior water right needs. Beyond minimal exports to meet South Bay health and safety needs, water stored in Lake Oroville will be used for south of Delta deliveries only if hydrology conditions improve. DWR plans to conserve as much storage as possible in Oroville in anticipation of a third dry year and potentially a dry 2023.

In addition, DWR along with the U.S. Bureau of Reclamation, submitted a new temporary urgency change petition to the State Water Resources Control Board.

If approved, the petition would allow the State Water Project and the Central Valley Project to operate under modifications to the water quality and water right permit requirements in the Delta from February through April 2022, should conditions warrant. These modifications may be needed to conserve water in Lake Oroville to ensure minimum health and safety water supplies are available later in the year if dry conditions persist.

If significant precipitation materializes in the next few months, standards may be met through natural means and modifications to State Water Project and Central Valley Project operations may not be necessary.

Removal of salinity barrier delayed

DWR is also delaying the removal of the emergency drought salinity barrier in the Delta. The rock barrier across West False River was scheduled to be removed by Nov. 30. However, drought conditions have persisted. And leaving the barrier in place will enable a more efficient drought response in spring 2022 if needed. DWR plans to create a notch in the barrier in January 2022 to allow for fish passage and boat traffic until April 2022.

“It is going to take a multi-pronged approach to successfully respond to these unprecedented drought conditions,” Nemeth said.

Each year, DWR provides the initial State Water Project allocation by Dec. 1 based on available water storage and projected water supply demands. Allocations are updated monthly as snowpack and runoff information is assessed, with a final allocation typically determined in May or June.

The lowest initial allocations were 5% in 2010 and 2014. Last year, the initial SWP allocation was 10%. However, due to increasing dry conditions, the final allocation was lowered to 5%.

The California Department of Water Resources contributed information for this article.

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