For hundreds of years, when giant redwoods and Douglas firs toppled into Lagunitas Creek, they stayed put. The stream flowed rapidly over decaying boughs and emptied into still, shady pools cordoned off by huge logs. It was an ideal spawning ground for tens of thousands of now-endangered coho salmon, which need shallow riffles to make redds, or gravel nests, and sheltered pools to rear their young.
In the last century, the watershed was dammed to create reservoirs, landslides became less frequent because of forest and land management practices, and there was always someone around—landowners, state park rangers, county staff—to remove fallen logs from the creek.
After decades of small projects, Marin Water is beginning an effort that could finally restore woody debris in Lagunitas Creek, a stronghold of central California coast coho, to its natural level. Last month, the district secured a $1.4 million federal grant to begin construction of three riffle-pool wood structures within Samuel P. Taylor State Park, the first of 13 projects that will with log to break up homogenous, uncovered “glides” in the creeks.
“Nothing at this scale has been tried in Lagunitas Creek,” said Jonathan Koehler, the district’s fisheries program manager.
A 2014 study by Mike Napolitano, an engineering geologist with the regional water quality control board, provided a baseline for the volume of logs and woody debris that would have been in the creek before dams, industrial uses and ranching. “We’re at 30 percent of what would naturally be in the creek,” Mr. Koehler said. “This project aims to get it up to 100 percent.”
The grant comes from the United States Bureau of Reclamation’s WaterSMART program, which itself was boosted by $26.7 million from President Joe Biden’s Bipartisan Infrastructure Law. It will fund the construction phase, beginning in 2024, of restoration projects in the works since 2020. The planning process identified 13 sites from the Leo T. Cronin Fish Viewing Area downstream to Camp Taylor, where spawning activity is the most vigorous; a $900,000 grant from the Proposition 1 water bond paid for environmental review and final designs for about half of them. The latest federal grant will cover construction costs for three of those. The district estimates the total construction cost for the 13 sites at $8.7 million.
“I’m glad that the federal government has put some funds toward this, because the state has put most of the effort into this watershed,” said Preston Brown, director of watershed conservation for the Salmon Protection and Watershed Network, which has completed smaller projects in San Geronimo Creek. “What [Marin Water] is trying to do is ambitious and commendable.”
Changes to state law in the 1980s and ‘90s spurred water districts to take an active role in restoring the fisheries they had harmed in preceding decades. Marin Water, the agency that built Peters and Seeger Dams, two of the most consequential barriers to salmon spawning, became the chief driver of fish habitat restoration in Lagunitas Creek in 1995, when the state water board passed an order mandating minimum streamflows and mitigation strategies.
Besides truncating the salmon spawning grounds, the damming of Lagunitas Creek blocked gravel and logs that make their way downstream from the slopes of Mount Tamalpais. By 2011, the district, along with groups like SPAWN and the Marin Resource Conservation District, had installed about 40 large wood structures, like logs and upturned roots, in the creek. In the high-priority spawning reach, up to half of the large woody debris in the creek had been placed through restoration projects.
The coho population in Lagunitas Creek, the most important holdout of the salmonid between Monterey Bay and Mendocino County, is stable. Last year’s heavy autumnal rains presaged the second-highest count in a decade. Early this year, surveyors found 330 redds, up from 173 last year and a paltry 63 in 2020. In early 2019, they counted 369, the best number in years.
Yet the population has never approached the threshold for full recovery. The world will never be the same for salmon, and habitat restoration has no effect on drought and ocean conditions.
But, Mr. Brown said, “what this can do is make fair habitat into really good habitat when it does rain.”