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NEWS: Mill Creek Dam Removed in Santa Cruz Mountains

Sempervirens Fund completes post-fire dam removal to restore creek and improve Coho salmon habitat, part of long-term restoration of previously logged redwood forest

Contact: Matthew Shaffer, Sempervirens Fund, 415.609.2750, [email protected]
Download a PDF of this press release.

Los Altos, Calif. (October 4, 2021) — Sempervirens Fund announced today that they have removed a dam on Mill Creek in the San Vicente watershed.

Timelapse of the removal of the Mill Creek dam in the San Vicente watershed. Credit: Ian Bornarth

“For more than a century Mill Creek dam impeded Coho salmon from reaching desperately needed spawning habitat,” said Sara Barth, Sempervirens Fund’s executive director. “Removing the dam has been a missing piece in restoring creek flow and improving sediment conditions critical for spawning. A restored creek is also essential to the health and resilience of the surrounding redwoods and other nearby and downstream habitats at San Vicente.”

The Mill Creek section of the San Vicente watershed is prized for its heavy summer flow of cold water—even in current drought conditions—largely due to a substantial limestone karst system underground. Highly durable granite cobble, trapped behind the dam for a century, can now make its way downstream and into the watershed system, improving miles of potential salmonid spawning habitat, especially for endangered Coho salmon, at the southern end of their range.

“Habitat for salmon is scarce and impediments like dams diminish their access to critical waters and the gravelly sediment that makes for ideal spawning grounds,” added Ian Rowbotham, Sempervirens Fund’s Land Stewardship Manager.

San Vicente Redwoods is an 8,852-acre stretch of forest that is currently owned and managed by four conservation organizations: Sempervirens Fund, Peninsula Open Space Trust, Save the Redwoods League, and Land Trust of Santa Cruz County. Near Davenport, it is the largest privately held redwood forest in the Santa Cruz Mountains. The CZU Lightning Complex wildfires in August and September 2020 scorched more than 86,000 acres, including all of San Vicente Redwoods lands. Water lines for Davenport, which ran across the top of the dam, were destroyed. CEMEX funded the re-routing and replacement of their water lines earlier this year and agreed to remove the dam. In late March Sempervirens Fund received a $550,000 grant made through the Open Rivers Fund, a program of Resources Legacy Fund supported by The William and Flora Hewlett Foundation. The grant has been further leveraged by support from individual donors for the ongoing restoration work at San Vicente. Funding for the project also came from the National Fish and Wildlife Foundation and the California Department of Fish and Wildlife, Office of Spill Prevention and Response.

Since 2011, the organizations have partnered to steward the property’s old-growth redwoods and eight creeks, home to many regionally important species of wildlife and plants, including the endangered Coho salmon. While rare in the Santa Cruz Mountains, dams like the one on Mill Creek were built early last century to support redwood logging. Their utility has long since expired, and removal is the best option for repairing the ecosystem. San Vicente’s partners also collaborate with regional conservation teams, such as Resources Conservation District Santa Cruz County, to implement large-scale restoration efforts.

“The RCDSCC is proud to partner with Sempervirens Fund and other local north coast partners to advance the removal of the lower Mill Creek dam,” said Lisa Lurie, Executive Director, Resource Conservation District of Santa Cruz County. “This project, identified as a priority action for recovery of salmonids in the San Vicente Watershed, is an important step forward in helping threatened and endangered Steelhead and Coho salmon along the Central Coast of California.”

Sempervirens Fund and its partners have also initiated research projects with the Amah Mutsun Land Trust, San Jose State University, and UCLA to monitor and survey fish populations in Mill Creek and in the greater San Vicente watershed, including Coho salmon, steelhead trout, and lamprey eels, including the use of environmental DNA techniques. Past restoration projects along Mill Creek, including the introduction of large woody debris, have already reinvigorated steelhead populations, which have been present this year.

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