Equivalent stormwater manuals for municipal stormwater permits

Here we provide information for municipal stormwater permittees and other interested parties about equivalent stormwater manuals for the Phase I Municipal Stormwater Permit and both the Eastern and Western Washington Phase II municipal stormwater permits.

Requirements for governments using equivalent stormwater manuals

These manuals require permitted cities and counties to establish enforceable programs to manage stormwater from new development, redevelopment, and construction activities. 

Eastern Washington requirements

Local governments in Eastern Washington must adopt a site planning process, and criteria for selecting and designing best management practices similar to those described in our Stormwater Management Manual for Eastern Washington.

Western Washington requirements 

Western Washington permittees covered under either permit must implement the following site planning requirements:

  • Best management practices (BMP) selection, design, and infeasibility criteria
  • BMP limitations
  • Low Impact Development (LID) competing needs criteria