King County, WA Landscaping Rules: Water Restrictions (2026)

Outdoor water use in unincorporated King County is governed by the retail water provider serving a given parcel. Seattle Public Utilities (Skyway, North Highline), Cascade Water Alliance member utilities (Sammamish Plateau Water and Sewer District, Covington Water District, Issaquah, portions of Bellevue), and exempt-well owners in rural areas each have different conservation programs. Washington water law operates under prior appropriation (first in time, first in right) administered by the Department of Ecology under RCW 90.03 and 90.44. Exempt-well users (up to 5,000 gallons per day for domestic use under RCW 90.44.050) are metered in some basins and subject to minimum-instream-flow rules (WAC 173-508 for the Snohomish basin). During drought declarations by the Governor or Department of Ecology, mandatory restrictions may be imposed. NPDES Phase I and II municipal stormwater permits issued by Ecology under the federal Clean Water Act (RCW 90.48) require King County to protect water quality, including restricting over-irrigation that causes runoff pollution. Residents should check with their specific water provider for watering guidance during summer months when salmon-stream flows are low.