Storm Runoff and the Petaluma Floodplain

To: The City of Petaluma, General Plan and DEIR management, Supervisor Kerns, and Members, Zone 2A:

Please add the following summary as comments on the Petaluma General Plan DEIR, and as a further definition of more effective and comprehensive objectives, policies and programs, which are currently absent from the DEIR and Draft General Plan.

The use of this “No Adverse Impact Floodplain Management” approach by the City of Petaluma and the County of Sonoma will help ensure an integrated management strategy that affects all development in the Petaluma River watershed with far better impacts than what is currently proposed and evaluated in the DEIR.

For example, one strategic policy that should be included within the General Plan and the DEIR is the requirement for Zero-net Increment in Stormwater Runoff, applied to all new development and to significant redeveloped sites upstream of the Downtown Reach of the Petaluma River. The Basin modelling should allow a parcel by parcel analysis of proposed changes and impacts throughout the basin, along with the policies and programs to eliminate off site impacts.

As the onetime Project Manager for the Corps of Engineers’ Petaluma River Flood Management Project told the City Council in about 1998, “you will need to make up for past mistakes in flood management in the Petaluma Valley, meaning that just staying neutral in runoff, flood peaks, and floodplain fill is not sufficient: you will have to ‘go negative’.”

Information about these policies and programs is readily available from the Association of State Floodplain Managers, at

David Keller
Petaluma River Council
1327 I St.
Petaluma, CA 94952