California's Marin County suspends Corte Madera Creek flood control project for review

The Marin County Flood Control District in California has paused flood control work along Corte Madera Creek pending a comprehensive review to determine if the project’s goals can be accomplished, the district announced Feb. 19.

The project, part of Zone 9 of the Marin County Flood Control and Water Conservation District within the Ross Valley watershed, faces "a combination of regulatory, technical, and community challenges that prevent it from moving forward in its current form," the district said.

"This pause gives us the opportunity to step back, reassess our approach, and ensure we are making responsible decisions on behalf of the community," Public Works Director Christopher Blunk said in the announcement. "We need to ensure that any future work along Corte Madera Creek is realistic, reduces flood risk, and reflects community input."

The district said the pause provides time to better understand  project constraints, FEMA mapping implications and flood-rise assumptions. No new spending on outside engineering and design consultants will be authorized during the review, it said.

The Corte Madera Creek Flood Risk Management Project aims to reduce flooding frequency and severity in the communities of Ross and Kentfield by improving a concrete channel originally built by the U.S. Army Corps of Engineers in the 1960s and 70s.

The project includes removing a fish ladder and lowering the channel in Unit 4, creating taller floodwalls in Units 2 and 3, enlarging fish resting pools in Unit 3 and removing portions of the concrete channel to restore wetland habitat, according to the district's project page.

The Federal Emergency Management Agency determined that remaining project work would increase downstream flooding risk, the Marin Independent Journal reported. To meet FEMA's requirements, the district said channel walls would need to be raised to a height that could obstruct views from a pedestrian and bike path along the creek and alter the aesthetic of the neighborhood. Alternatively, the district said, mitigations may be required for downstream properties.

The pause follows a similar FEMA-related setback for a separate project to remove Building Bridge 2 in San Anselmo, which requires unanimous consent from 12 downstream property owners before demolition can proceed, according to the Marin Independent Journal.

Frank Egger, a Zone 9 advisory board member and vice mayor of Fairfax, Calif., told the Marin Independent Journal that the fish ladder's removal has been a priority for ecological reasons.

"I've been trying to get that old fish ladder removed because it blocks salmon passage in Corte Madera Creek coming up towards the upper reaches of the Ross Valley," Egger said. 

Sandra Guldman, president of the Friends of Corte Madera Creek Watershed, a partner of the project, wrote in a Marin Independent Journal opinion piece published Saturday that the suspension "was an overreaction to a determination by the U.S. Federal Emergency Management Agency that one component of the Corte Madera Creek flood risk reduction project might cause downstream flooding."

"It appears that only one of these three listed projects would risk possible flooding: removal of the fish ladder," Guldman said. "A crucial fact is that enlarging the fish resting pools would not change water levels downstream and would not cause flooding."

Guldman said the current concrete channel conditions may violate the federal Endangered Species Act because the upstream half acts as a velocity barrier to fish passage.

"Nearly all steelhead swimming upstream trying to spawn become exhausted and are swept downstream by the fast-moving water," she said.

Environmental analysis firm Michael Love and Associates designed larger pools, Guldman said, that are "expected to dramatically improve fish passage and allow almost all spawners to reach the fish ladder."

Guldman warned that the blanket pause jeopardizes existing approvals and grant funding.

"It would be wise to proceed with enlarging the resting pools before the permits and approvals expire," she said. "Stopping work could jeopardize the Department of Water Resources grant that has funded a significant part of the project."

“There are designs for increasing the capacity of the concrete channel other than raising the existing concrete walls," she said, "designs that could improve safety, user experience and habitat along this reach of the creek."

The overall project cost is estimated at about $18 million, with construction phases estimated at roughly $12 million, according to the district. Funding sources include the California Department of Water Resources, the State Coastal Conservancy, the U.S. Fish and Wildlife Service and the Zone 9 storm drainage fee, among others.

Marin County Supervisor Brian Colbert told the Marin Independent Journal that the Corte Madera Creek project and the Building Bridge 2 removal in San Anselmo both need reassessment.

"We really need to understand where this process veered off course so we can correct it and prevent similar issues elsewhere," Colbert said.

The Corte Madera project has $3 million in California Department of Water Resources grant funds expiring at the end of March. The bridge removal project holds $2.2 million in state grant funds set to expire at year's end.

A 20-year stormwater drainage fee generating roughly $2.6 million annually for flood control in the Ross Valley sunsets in June 2027. Without it, Zone 9 projects an operating deficit exceeding $200,000 in fiscal year 2028 against a current fund balance of $6.6 million.