Bellevue, WA Environmental Rules: Stormwater Management (2026)

Bellevue administers stormwater regulation under Bellevue City Code Chapter 24.06 (Storm and Surface Water Code) and Land Use Code 20.25H (Critical Areas). New development, redevelopment, and certain site alterations that add or replace 2,000 square feet of impervious surface, clear 7,000 square feet of land, or convert native vegetation, typically trigger stormwater review under the Department of Ecology 2019 or current Stormwater Management Manual for Western Washington. Projects must install flow-control BMPs (detention, infiltration, or rainwater harvesting) and water-quality treatment facilities (bioretention, filtration) sized for site conditions. Low-impact development (LID) is required first to the extent feasible under Ecology rules. Critical areas (streams, wetlands, steep slopes, flood hazard areas, and aquifer recharge zones) have buffer requirements that limit clearing and impervious surface. Illicit discharges to storm drains (paint, soap, oil, sediment-laden water) are prohibited and subject to fines under BCC 24.06.530. Bellevue inspects catch basins, streams, and private stormwater facilities and requires recorded maintenance agreements for private systems. Residents can report spills or clogged storm drains through MyBellevue.