Edmonds, WA Environmental Rules: Stormwater Management (2026)

30 ECDC applies to any site that discharges to the city's municipal separate storm sewer system (MS4) or to waters of the state, whether or not a city permit is otherwise required, covering land-disturbing activity, creation or replacement of hard surfaces, conversion of pervious surfaces, and new connections to the MS4. The chapter sorts projects into two tiers. Category 1 sites, those adding 2,000 square feet or more of new plus replaced hard surface or disturbing 7,000 square feet or more of land, must meet Minimum Requirements No.

1 through No. 5, covering a stormwater site plan, a construction stormwater pollution prevention plan, source control BMPs, preservation of natural drainage, and on-site stormwater management. Category 2 sites, those adding 5,000 square feet or more of hard surface or converting three-quarters of an acre or more of vegetation to lawn, must additionally meet Minimum Requirements No. 6 through No. 9 for treatment and flow control. All standards flow from the Western Washington Phase II Municipal Stormwater Permit, the 2019 Stormwater Management Manual for Western Washington, and the city's own Edmonds Stormwater Addendum, with the more stringent provision controlling any conflict.

The public works and utilities director administers the chapter, reviews stormwater site plans, and inspects projects before clearing, during construction, and after completion, including inspections of permanent treatment and flow control facilities every six months in new residential developments until 90 percent of lots are built. 200 ECC.