Grant County, WA Environmental Rules: Stormwater Management (2026)

080, Clearing, Grading and Drainage Standards, governs stormwater in the unincorporated county under the Unified Development Code's Title 23 zoning chapter. 08. The Code points builders to a specific outside standard rather than a home-grown one: erosion and drainage control on any construction site must conform to the Washington State Department of Ecology's Stormwater Management Manual for Eastern Washington, unless the County Engineer specifies otherwise for the site. Runoff cannot be discharged onto County roads or roadside ditches within county right-of-way without the County Engineer's approval, and the Engineer can require landscaping, re-established native vegetation, ponds, catch basins, or biofilters wherever downstream damage to property or water quality is likely.

When the County Engineer determines a project needs one, the applicant must submit a drainage report sealed by a professional engineer describing the proposed controls; the County Engineer's decision on the adequacy of that report and the stormwater measures is final and cannot be appealed administratively. 080 for the technical requirements. Any Decision Maker reviewing a development permit application may add clearing, grading and drainage conditions of approval to meet these standards, so stormwater compliance can be tightened project-by-project rather than left to one fixed number.