All property in Alameda County contributes stormwater runoff that may cause flooding. Eliminating flood damages to homes, apartments, schools, streets, highways, stores, factories, and public facilities benefits everyone in the District.

The District levies benefit assessments to help finance flood control operations. Benefit assessments are proportionate to the stormwater runoff from each parcel of land—meaning the amount of stormwater that flows off the property and into street storm drains, flood control channels, and creeks, or that otherwise impacts flood control infrastructure.

The purpose of the benefit assessment is to supplement other District revenues sufficiently to

  • keep the District’s existing flood protection system safe and effective,
  • enable emergency response,
  • help pay costs of ongoing flood control maintenance and repair, and
  • provide for the completion of authorized projects and programs.

Benefit assessments are set annually by the Alameda County Board of Supervisors. They are not property taxes and are not tied to property values. The assessment program applies to all of Alameda County, with the exception of the cities of Alameda, Albany, Berkeley, and Piedmont and the Zone 7 area east of the hills (Livermore-Amador Valley).

Your Tax Bill

The benefit assessment amount appears on your tax bill. There is a line item labeled “Flood Benefit” followed by a number that indicates the zone in which your property is located.

More Information

See Benefit Assessment Frequently Asked Questions (FAQs).


Alameda County Flood Control & Water Conservation District
Phone: 510-670-5480

Benefit Assessment Program
Phone: 510-670-5762

County Assessor’s Office
Phone: 510-272-3787