Mill Valley marsh restoration effort gets $670,000 grant

A proposal to restore marshlands and bolster sea-level rise protections at the edge of the Richardson Bay in Mill Valley scored a $670,000 grant to boost project planning and design.

The Metropolitan Transportation Commission awarded the grant to the Golden Gate National Parks Conservancy last week to fund environmental review and regulatory permit applications for the proposed project at the 106-acre Bothin Marsh Preserve.

“The marsh itself is currently drowning through this muted tidal effect,” said Rob LaPorte, a project manager at the conservancy. “It takes longer for the tides to drain from the marsh than a normal functioning marsh.”

“So we’re losing vegetation and we’re losing whole sections of the marsh to wave erosion,” he said. “We’re making sure we get a project implemented as fast as possible in order to restore the marsh and all of the rare wildlife and plants it supports.”

The scenic marsh provides habitat to more than 400 species of migratory birds, including the state threatened California black rail and the federally endangered Ridgway’s rail. The high marsh also supports rare plants, such as the Point Reyes bird’s beak.

Sea-level rise is threatening to erode the marsh in as few as 25 years if nothing is done. The flood-prone Bay Trail, also known as the Mill Valley-Sausalito Multiuse Path, is inundated by high tide at least 30 days of the year. With 1 foot of sea-level rise, the path could flood in sunny conditions nearly 220 days a year.

The restoration is part of the evolving shorelines initiative, an effort in collaboration with the One Tam, a partnership of public agencies.

Planners are developing nature-based strategies to protect, restore and enhance the tidal wetlands.

A key component of the project involves realigning the flood-prone Bay Trail to the edge of the marsh. Today the trail runs along an old rail line that goes through the marsh. The realignment would remove the trail from the flood threat, improving public access, safety and connectivity.

“Without the One Tam partnership, we wouldn’t be able to do these much bigger projects,” said Mischon Martin of the Marin County parks department.

“The Bay Trail is the biggest, most used active transit corridor used in Marin by schoolchildren as part of Safe Routes to Schools, by commuters to and from Marin and San Francisco,” Martin said. “And it’s underwater at least one month a year. This is a big priority regionally and it has been for a long time.”

The funding is part of a $8.5 million disbursement of priority conservation area grants to 13 Bay Area organizations. Projects selected for funds support the goals of Plan Bay Area 2050, the nine-county Bay Area plan for housing, economy, transportation and the environment. This is the third round of priority conservation grant awards.

Ben Botkin, the grants program manager at the San Francisco Estuary Partnership, said the Bothin Marsh project fit the bill because it involves realigning the heavily used section of Bay Trail “in a way that supports overall ecological health, is more resilient to sea-level rise and still meets the recreation needs.”

Warren Wells, policy and advocacy director at the Marin County Bicycle Coalition, said the organization supports the project.

“Ultimately, the project being designed improves the health of the marsh and keeps the pathway above rising sea levels, improving the reliability of the path that is prone to flooding,” Wells said.

Other benefits include better access to Tamalpais Junction, Wells said.

So far, the project team has raised about $4.1 million, including two grants from the San Francisco Bay Restoration Authority amounting to about $2 million.

Planners have completed the project vision and conceptual design. The new grant will get planners to about 65% of project design, which could take about two to three years, LaPorte said.

Planners will be seeking about another $1 million to launch the project into final design.

The construction of the project is expected to cost tens of millions of dollars more, LaPorte said, but the plan won’t be shovel-ready for a few years.

“We’re looking at around 2028 to 2030 for implementation,” which could happen in phases, he said.

“It is possible we might do some of those marsh restoration measures first and then build a trail out incrementally, but we’re still exploring how that works and getting approvals for all that,” he said.

More information on the Bothin Marsh project is at onetam.org/our-work/bothin-marsh.