Published: July 21, 2020
On May 19, 2020, Sonoma Water’s Board of Directors adopted a resolution approving the Flood Management Design Manual (FMDM) dated March 2020 to provide guidance and criteria for the conveyance of storm water. The FMDM is a significant update to the existing
criteria and will replace the current Sonoma County Water Agency Flood Control Design Criteria (FCDC) last revised in 1983. The FCDC has been a reference tool used throughout the County since 1966.
The FMDM is intended to be used to guide public agencies and private entities in Sonoma County that are planning, designing, constructing or maintaining waterways, stream channels, closed conduits, culverts, or other drainage features. It provides methods and criteria for analyzing storm drain
systems and facilities that are necessary to convey rainfall run-off from 10-year storm events or larger. Effective immediately, Permit Sonoma will require new permit submittals to utilize the FMDM criteria.
The current version of the new
FDMD can be found on the Sonoma
Water website. Please note that the website is in the process of being updated but the version posted is the current version.
If you have any questions about the manual, please contact Philip Wadsworth via email at
Phil@scwa.ca.gov or visit Sonoma Water online at