FEMA provides the technology and relies on our community’s leaders to share local knowledge and plans to make the maps as accurate as possible.

The process:

  1. Petaluma’s assigned Floodplain Administrator, the Assistant Director of the City’s Public Works and Utilities Department, with authorization of our elected officials, contracts professional engineers and hydrologists to collect rainfall and storm flow data and create the hydraulic models and associated  maps.
  2. Community members are invited to provide information to help local officials better understand how water drains in the area (the people who live here are experts in what happens here!).
  3. The City then provides the updated model data to FEMA for review and approval.  The review process includes cooperative discussions between FEMA and the City before the updated FIRM is created and distributed.

Floodplain maps are modified when there are changes in population growth and development, and improved science including changes in climate and weather patterns. Modeling can also be advanced and revised with technological advances in hydraulic modeling. FEMA, state, local and tribal officials collect current and historic flood-related data, which includes hydrology, infrastructure, hydraulics, land use, and existing maps. It will take 2-3 years to complete the physical analysis, submit, and conclude the FEMA review process.

Once the data analysis is done, preliminary flood maps will be available for review. Before our community decides to adopt the maps, we have 90 days to submit technical data to support an appeal to the map.  Because Petaluma is a participant in the NFIP, we are required to adopt the FEMA FIRMs and implement appropriate measures to protect properties from flood impacts.

Any time after our community adopts the maps, we can submit data to amend or revise the flood map through the Letter of Map Change (LOMC) process.

Learn more HERE.

Denman Reach
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