Huge piles of redwood logs will divert waters in Lagunitas Creek, once Marin Municipal Water District completes a project simultaneously aimed at creating winter fish habitat and storing harmful sediment.
The project targets five sites located on federal parkland between Jewell and Nicasio Creek, where a lack of side channels and floodplain is suspected of limiting the number of endangered salmon and trout that survive the winter, according to the district’s fishery program manager, Gregory Andrew. It should be completed next summer.
The district has a keen interest in the resource that provides water to thousands of customers. Two years ago, it spearheaded an assessment of winter habitat problems for coho and steelhead along the creek, which travels through federal, state and county land as it flows from Mount Tamalpais to Tomales Bay. The study put the agency in a “prime position” to take the lead for the project, Mr. Andrew said.
Last week, the National Park Service initiated a four-week public scoping period for an environmental review.
Over the past 18 years, M.M.W.D. has installed woody debris at about 60 sites, using just two to four redwood logs per site. These smaller installations were meant to create or improve summer habitat: small, calm pools that act as a refuge for fish.
The new project will use 20 to 30 redwood logs at each site. The installations will span most of the creek width, forcing flows into side channels to create floodplain and creating calmer backwaters during the winter.
“We want to see [these areas] get flooded and inundated more regularly under more normal winter flow conditions and smaller storm events,” Mr. Andrew said.
The project will hopefully also improve the quality of the designated impaired water body, as extra floodplain could help store more sediment, too much of which can interfere with salmon nests.
In the past, fall estimates of the number of juvenile coho in the creek varied, from just a few thousand to 25,000. One study found that no more than 7,000 coho smolts made it out of the creek to Tomales Bay and on to the ocean from 2006 to 2008.
“Something was happening in the wintertime that, regardless of how many [coho ] were in the creek in the fall, they’d go through winter and the numbers got capped at around 7,000,” Mr. Andrews said.
Though he could not say exactly what was happening, he said that “only so many fish can occupy an undercut bank, or a given square foot of channel.”
Though the number of surviving smolts rose somewhat in the past two years—an estimated 10,000 made it out last spring—Mr. Andrews still believes the project will allow more to survive the winter. He also hopes survivors will be bigger, boosting their chances of reaching spawning age.
Phase I of the project, which will cover five sites, the environmental analysis, planning and construction, will cost about $700,000, with grants totaling about $500,000 coming from the California Department of Fish and Wildlife and the U.S. Fish and Wildlife Service. (The district will fund the remainder.) Mr. Andrews said a second phase would cover another five sites but that funding is tentative.
Mr. Andrews hopes the work will help the creek meet a federal recovery goal of 2,500 adult coho that return to spawn. The average these days is about 500. “The more smolts that go out into the ocean, the greater the chances that more return,” he said.
To comment on the proposal and suggest issues or alternatives that should be addressed in the forthcoming environmental assessment, visit parkplanning.nps.gov/lagunitas and click the “Open for Comment” link, or mail comments to Lagunitas EA c/o Superintendent, Point Reyes National Seashore, 76 Bear Valley Road, Point Reyes Station, CA 94956. Comments are due Jan. 11.