What is Floodplain Management?
Floodplain management is the operation of a community program of corrective and preventative measures for reducing flood damage. These measures take a variety of forms and generally include requirements for zoning, subdivision or building, and special-purpose floodplain ordinances.
A community's agreement to adopt and enforce floodplain management ordinances, particularly with respect to new construction, is an important element in making flood insurance available to home and business owners. Currently over 20,100 communities voluntarily adopt and enforce local floodplain management ordinances that provide flood loss reduction building standards for new and existing development.
Update: The Federal Emergency Management Agency (FEMA) is responsible for the preparation of Flood Insurance Rate Maps for the National Flood Insurance Program (NFIP). FEMA recently completed a major map modernization program to convert paper maps to digital format, with new maps for Marin that became effective May 4, 2009. FEMA is now conducting riverine studies (flood studies) within the Ross Valley and Mill Valley watersheds. These studies will result in revised Flood Insurance Rate Maps for these areas, which may include a change in flood risk classification for some property owners or add properties to a Special Flood Hazard Area.
https://walrus.wr.usgs.gov/coastal_processes/sfbaycoastalsys/ - USGS San Francisco Bay Coastal System
https://www.floodsmart.gov/ - Official site of the NFIP
http://www.marinmap.org/dnn/Home.aspx - MarinMap