Environmental

Genetic technology helps California DWR identify endangered fish

Genetic technology helps California DWR identify endangered fish
(photo courtesy California Department of Water Resources)

The California Department of Water Resources (DWR) is using genetic technologies to more accurately identify endangered fish at its State Water Project (SWP) pumps in the Sacramento-San Joaquin Delta.

Along with improved accuracy to quickly determine whether a fish is endangered, the new technology has the additional benefit of preventing unnecessary reduction in water capture, which makes that water supply available for Californians.

Starting in January 2023, DWR spearheaded the use of genetic tools at both the SWP and the Central Valley Project (CVP) pumping facilities to more accurately guide operations for endangered run protection.

The genetic technology, similar to testing for COVID-19, is being used to more accurately guide water operations for endangered species protection. Central Valley rivers support four unique runs of chinook salmon, defined by the timing of adult spawning migrations. However, only two of those salmon, winter-run and spring-run, are protected under the federal and California state Endangered Species Acts.

“DWR is using the best available science to improve our operations to balance both environmental and community water needs,” said DWR Director Karla Nemeth. “As we adapt to climate extremes with more uncertainty about how much water will be available, it is critical to use these innovative approaches in our water management practices.”

The previous method for run-type identification for juvenile salmon at the south Delta pumps, which has been used for nearly 50 years, is the “length-at-date” approach. This measures a fish and determines its run based on its length on the date it was captured. However, this method leaves room for misidentification because there can be substantial overlap in the size of juveniles from the different runs, DWR said.

California is already seeing the benefits of using the genetic technology. After the series of winter storms in January, a juvenile salmon was recovered at the state’s pumping facilities. Under the length-at-date method, it would have been assumed to be an endangered winter-run chinook salmon and would have triggered a mandatory five-day pumping restriction. That restriction could have resulted in a reduced capture of 15,000 acre-feet of water for human use. But genetic tests determined the juvenile salmon was not from an endangered run and pumping continued. Using genetic tests allowed capture of enough additional water to supply up to 30,000 households for a year.

The SWP provides water to 29 public water agencies that serve 27 million Californians and also uses the water for hydropower generation. The SWP is a system of 32 storage facilities, 21 pumping plants, four pumping-generating plants, eight conventional hydroelectric plants and about 700 miles of canals and pipelines. Among these generating plants is the 762 MW Hyatt Powerplant at the foot of Oroville Dam.

The CVP supplies water to about 3 million acres of agricultural land in the San Joaquin and Sacramento valleys and provides urban water for millions of people and industrial water. In addition, water from the CVP is vital for the environment, wildlife and fishery restoration, and hydroelectric power production. The CVP’s major reservoirs are (from north to south) Trinity, Shasta, Folsom, New Melones, Millerton, and the federal share of San Luis Reservoir. The Shasta powerhouse has a capacity of 633 MW, Folsom 198.72 MW, New Melones 300 MW and Trinity 140 MW. San Luis Reservoir provides water to the 424 MW William R. Gianelli pump-generating plant.