Marin cancels Building Bridge 2 project, will withdraw FEMA CLOMR after modeling and mitigation concerns

Marin County staff recommended withdrawing the FEMA conditional Letter of Map Revision (CLOMR) and formally canceling the long‑running Building Bridge 2 removal project in downtown San Anselmo, and the board unanimously approved that recommendation on May 5.

Public Works Director Chris Blunk described a decades‑long program of Ross Valley flood risk work and said that upstream detention basins originally envisioned to mitigate downstream impacts were not constructed, leaving the downstream reach vulnerable to increased flood elevations if the bridge obstruction were removed. FEMA’s technical review of the district’s CLOMR application identified downstream rises and concluded the district would need to install mitigations on affected downstream properties before proceeding.

Blunk told the board the district has already spent about $6 million on the project and estimated roughly $5.1 million more could be required to complete removal and mitigations, with additional modeling and permitting costs and a looming grant deadline. Given the technical, permitting and financial uncertainty and the need for community trust, staff recommended canceling the project, maximizing reimbursements where possible, closing out environmental testing (including contaminated soils from an old fuel tank), and pursuing alternative flood risk strategies for the Ross Valley.

Supervisor Colbert supported the recommendation, saying the project as structured was unlikely to succeed and the county should “reset” to pursue achievable, community‑supported measures. The board voted to withdraw the CLOMR, cancel Building Bridge 2 removal and direct staff to pursue alternative flood‑risk reduction and funding reallocation options.