Denman Reach Phase 4

Project Description

The City has been proactive to mitigate flooding within the Petaluma Watershed along with development of a river and creek front trail system, was envisioned in the City’s 1996 River Access and Enhancement Plan and in the General Plan 2025.

At completion, the four phases of the Denman Reach flood mitigation projects will meet this policy. Flood plain modeling conducted identified that the completed project (all four phases) will lower the flood elevation for a one-hundred-year storm up to 1 foot in areas around Industrial Avenue and Corona Road.

In Phases 1 through 3, work conducted from 2005 through 2018 included: 1) Acquiring several vacant parcels; 2) Developing permanent trail easements and trails; 3) Opening the river channel with terracing; and, 4) Creating wetlands and riparian habitat. This final phase began in the fall of 2016, when the Sonoma Water Agency (Agency) approached the City with a grant opportunity for $1.9 million from the California Department of Water Resource (DWR) Proposition 1E funds for a flood mitigation project.

The Phase 4 project includes:  1) Acquiring the last undeveloped parcel on Industrial Avenue on the river side, 5.47 acres purchased in 2018); 2) Developing a multi-use trail; 3) Creating two flood detention basins; 4) Developing mitigation wetlands and riparian habitat; and 5) Removing sediment buildup in the Petaluma River stream channel at the Corona Road Bridge while reducing further erosion.

Project Manager: Ken Eichstaedt – Senior Civil Engineer