About the dams we regulate

The dams we regulate:

  • Store at least 10 acre-feet (or 3.2 million gallons) of water
  • Are mostly under 50 feet tall
  • Are mostly earthen-fill dams
  • Are mostly privately-owned
  • Were mostly built for irrigation or recreational purposes

Dams in the state of Washington

Thirty-seven percent of the dams we regulate are considered "high hazard" or "significant hazard" because they are located above populated areas. We generally do not regulate hydroelectric project dams.
While we regulate the majority of dams in Washington, we are not the only regulator. There are 145 dams that are owned and/or regulated by one or more of the following government entities:

Unpermitted dams

Some dams in Washington exist that are not, but should be, regulated by Ecology. These dams are identified from publicly available aerial photos; they appear large enough to require a permit but are not listed in our inventory of dams. As funding and staffing allow, we proactively inspect unpermitted dams that pose hazards to downstream homeowners.

Zosel Dam

Zosel Dam is the only dam we own and operate.