In response to paltry rainfall and worsening drought, the Marin Municipal Water District is studying whether it could curtail reservoir water releases meant to support fish in Lagunitas Creek.
The district is required to release water from its largest reservoir at Kent Lake to bolster the fish population, including the largest population of endangered coho salmon remaining between Monterey and Mendocino counties. The construction of district dams and reservoirs since the 19th century has cut off half of the historic habitat and spawning grounds for the endangered salmon, threatened steelhead trout and other species, significantly reducing their populations. Once believed to run in the tens of thousands, coho salmon have dwindled to dangerously low levels in Lagunitas Creek and are listed as a federally endangered species.
But after two dry winters, including just 20 inches of rain this season — the second-lowest amount in 143 years of records — the water district has been considering several ways to stretch the life of its reservoirs. This month, the district board voted 4-0, with director Monty Schmitt absent, to begin studying whether it would be possible to temporarily reduce water releases into Lagunitas Creek without causing significant harm to the struggling salmon and threatened steelhead populations.
Schmitt, who is a watershed scientist and water project director with the Nature Conservancy, said Friday that Marin is facing dry conditions of “historic proportions.”
“The district is looking at every possible way to save water while meeting our obligations to be good stewards of our natural resources,” he said. “The fisheries study will help us better understand the benefits of flow releases that provide habitat for fish, and in doing so, may also help identify ways to release water more effectively and save some water in the process.”
The district hired the Environmental Services Associates firm to conduct the study by approving a nearly $306,000 extension to the firm’s contract into July 2022.
The state’s water regulatory board first ordered the water district to develop a plan in 1995 to address impacts of water diversions on coho, steelhead and other wildlife such as California freshwater shrimp. As part of the state’s order, the district is required to maintain adequate flows for the fish throughout the year.
The district releases pulses of water from Kent Lake, its largest reservoir, into the creek between November and January to support the migration of federally endangered coho salmon and threatened steelhead trout during their spawning seasons. Water releases continue into March to aid with spawning and hatching of the young fish, which in the case of coho must reside in the creeks and tributaries for about 18 months before swimming out to the ocean. Recent water releases range from about 4,700 acre-feet in 2015 to 9,000 acre-feet in 2019, according to the district.
However, the district is able to request a temporary change in these water releases in urgent situations such as a prolonged drought reducing supplies. The district’s seven reservoirs are about half full with nearly 42,000 acre-feet stored — about 32,000 acre-feet less than average for this time of year. The district board of directors plans to vote on mandatory water use restrictions on Tuesday, including a one-day-per-week irrigation limit, in an attempt to preserve its supply.
Local conservation groups and members of the Lagunitas Creek Technical Advisory Committee expressed appreciation that the district is conducting a full study of the potential impacts before making a decision. Committee member Todd Steiner of the Olema-based Salmon Protection and Watershed Network organization urged the district to consider all other options before reducing flows for fish.
“People have to be able to drink water, but they don’t have to water their lawns and don’t have to fill their swimming pools,” Steiner said. “We understand the need for balance but we want to ensure all conservation measures are in place at first and that they’re strong, effective and enforced.”
Committee member Ann Thomas, board secretary for Friends of Corte Madera Creek, said there should always be sufficient water in the creek to support the at-risk salmon population.
“I trust them to do the right thing in this situation but I know there is a lot of pressure for that water,” Thomas said. “I think they’ll be very careful and I do think it’s a good board for something like this. Nobody knows if it’s going to rain next year. And that’s the problem.”
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April 15, 2021 at 02:00PM
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Marin district might tighten water releases for fish - Marin Independent Journal
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