MarinIJ: Mill Valley Wetland and Path Projects Gain Momentum
After a decade of study and public comments, plans are taking shape to restore Bothin Marsh and move the popular path linking Mill Valley and Sausalito.
The Marin County parks department is delving into design details to build a new elevated path along the western edge of the marsh.
“This not a trail project and it’s not just a restoration project; it’s both,” Tara McIntire, the project manager, told the county Parks and Open Space Commission on July 16.
“On the trail side, we’re adding trailheads, we’re adding overlooks and we’re just improving conditions,” she said. “And then on the marsh resilience side, we have tidal channel improvements, and thin lift — which is basically adding sediment, marsh restoration and then coarse beach features and the other resilient measures.”
Bothin Marsh is in the northwest part of Richardson Bay between Mill Valley and Tam Junction and to the west of Highway 101.
“Decades of historic fill, channelization and construction of the former railroad embankment — now the Mill Valley-Sausalito Pathway — have disrupted natural tidal processes, reduced sediment delivery, and contributed to marsh degradation,” a staff report said. “Today, the existing pathway floods more than 30 days each year during king tides and storm events, affecting one of Marin’s busiest bicycle and pedestrian routes and a designated Safe Routes to Schools corridor.”
On July 14, two days before the commission met, more than 7,500 people used the path, said Chris Chamberlain, the county parks director.
The new 18-foot-wide path would “ring the marsh” and be 6 feet higher than the current path to avoid king tides, storm surges and the rising sea level.
An elevated boardwalk on piers would follow Almonte Boulevard south from Mill Valley and continue on an embankment behind Tam Junction.
Farther south, a new bridge would cross Coyote Creek and merge with the McGlashan Pathway leading to Sausalito – which would be raised.
“The project will replace approximately 1,800 feet of existing Bay Trail with approximately 3,800 feet of new trail,” the staff report said.
Once built, the 10-foot-wide path now bisecting the marsh would be removed to revive a sinking wetland and endangered ecosystem.
The details were part of an update for new parks commissioners by one of the lead agencies on the project.
Since 2016, the project has been led by the county parks department, the nonprofit Golden Gate National Parks Conservancy and the One Tam Partnership, a collaboration of public land management agencies. The marsh ecosystem and factors behind its decline have been extensively studied. More than 40 public meetings and presentations have been held.
“We were giving that presentation to bring all the commissioners up to speed,” McIntire said Wednesday. “We’ve been in the background working on these preliminary designs.”
Later this year, county parks officials will begin state and federal environmental reviews that might take two to three years. Public presentations will follow as the designs are further developed.
The reviews, additional technical studies and permit applications will precede the search for funding. The project costs will be in the “tens of millions,” Chamberlain said. Construction could take an additional two to three years.
During questions and discussion, commissioners were concerned about coordinating with other agencies, especially Caltrans, and ensuring that the path users – especially dog walkers and cyclists – have ample room and do not get in the way of one another.
“I’m just a little curious if Caltrans has alluded to any work they’re doing,” said Erika Lovejoy, the commission chair. “I know you’re working with them, just so it doesn’t rain on your parade, so to speak. … Are they moving along with any plans for road improvements?”
Chamberlain said Caltrans plans to replace the Highway 1 bridge and pedestrian crossing over Coyote Creek in the next five years, but that is not part of the Bothin Marsh project.
Commissioner Michael Dyett cautioned the parks agency not to “get too far in design development … without making sure that everyone’s on the same page.”
“We are all talking,” McIntire said. “And really making sure we’re not duplicating efforts and that we’re partnering with each other.”
Commissioner Joe Burns asked about the hydrology studies that led to elevating the proposed elevation of the new path by 6 feet.
“I’m curious how that’s measured, given that we know Manzanita has dropped about 2-and-a-half to 3 feet in subsidence; areas of Sausalito’s Marinship from 6 to 8 feet in subsidence since it was constructed in the 1940s,” he said.
McIntire said she would forward some technical reports. Earlier, she said the marsh restoration and path planning was relying on the sea-level rise projections used by all Bay Area agencies and municipalities.
“As a cyclist, the thing I’m worried about most is dog walkers with long extendable leashes,” said Joe Meylan, a parks commissioner. “I almost feel like you need to make one track that just for the cyclists.”
“I know they’re all supposed to go 15 miles and hour,” he said, “but it’s rare that someone will keep to it.”
McIntire said the proposed 18-foot width of the path and “how is that divided” among users for safety is an ongoing discussion.
“It’s complicated,” she said. “Yes, really complicated.”
During public comments, the emerging plans drew praise and minor suggestions.
“It’s a big complex project. It’s very ambitious and it’s really wonderful,” said Larry Minikes, a former Marin Conservation League board member, who suggested planners “look at traffic calming.”
“MCBC has been tracking this project since its inception and we’re wholeheartedly committed to seeing its completion,” said Warren Wells, Marin County Bicycle Coalition policy and planning director.
“While some of our members were skeptical about the realigned route, which will slowly lengthen the distance for riders traveling between Mill Valley and Sausalito, we believe the full project will substantially improve access to Tam Junction, Tam Valley and the Almonte neighborhoods, and that outweighs any of those longer travel times,” Wells said. “I’ll say firmly that we believe the project is being well designed and have no substantial concerns at this time.”
“I’ve been tracking this for more than a decade, two decades, more than that,” said Nona Dennis, who has lived in Mill Valley for nearly 70 years. The project is “one of the most transparent, public oriented processes you can imagine,” she said, recalling past dredging of upper Richardson Bay and plans to turn Bothin Marsh into a recreation center.
“So this is a miraculous transition, a miraculous point,” Dennis said.