Environmental Rules in Grant County, WA (2026)
4 rules for unincorporated Grant County, Washington.
Verified from official government sources
Stormwater Management
In unincorporated Grant County, new development must control stormwater runoff so it does not harm neighboring land, water quality, or critical areas. Grant County Code section 23.12.080 requires clearing, grading, and drainage on regulated projects to follow the Washington State Department of Ecology's Stormwater Management Manual for Eastern Washington, with the County Engineer approving control measures.
Grant County Stormwater and Drainage Rules
Some RestrictionsGrant County Unified Development Code § 23.12.080
(b)Stormwater runoff from developments shall not adversely affect offsite property, surface water quality and quantity, and/or critical areas as delineated in GCC § 24.08. Provisions shall be made to control the release of surface water runoff from the development both during and following construction.(c)Clearing and grading, including drainage and erosion control measures, shall conform to th...
Erosion Control
Grant County requires all clearing, grading, and development to control erosion and stormwater under UDO § 23.12.080, tying county-level drainage and erosion-control work to the Washington Department of Ecology's Stormwater Management Manual for Eastern Washington.
Erosion & Drainage Control, Grant County
Some RestrictionsGrant County Unified Development Code § 23.12.080(a)-(d)
23.12.080 - Clearing, Grading and Drainage Standards (a)Clearing and grading activities shall be conducted so as to minimize potential adverse effects on offsite property, surface water quality, and critical areas as delineated in GCC § 24.08.(b)Stormwater runoff from developments shall not adversely affect offsite property, surface water quality and quantity, and/or critical areas as delineate...
Flood Zones
Any construction or development inside a mapped special flood hazard area in unincorporated Grant County needs a development permit under GCC Chapter 14.02 before work starts. The Development Services Director serves as floodplain administrator and reviews plans against the county's Flood Insurance Rate Maps before signing off on structures, fill, or manufactured homes.
Grant County Floodplain Development Permit
Some RestrictionsGrant County Code § 14.02.130
A development permit, processed in accordance with GCC chapter 25.04 of the UDC, shall be obtained prior to construction or development within any area of special flood hazard as established in this chapter. The permit shall be for all structures and manufactured homes, as set forth in the "definitions", and for all development including fill and other activities, also set forth in the "definit...
Flood Elevation Requirements
New homes and substantial improvements built in Grant County's AE, A1-30, or other A-zone flood areas must sit at least two feet above the base flood elevation, the freeboard standard set by GCC 14.02.190. Commercial buildings face the same two-foot floor rule or the ASCE 24 minimum, whichever is higher, and manufactured homes must meet it too.
Grant County Base Flood Elevation Freeboard
Some RestrictionsGrant County Code § 14.02.190
(a)Residential Construction: In AE and A1-30 zones or other A zoned areas where the BFE has been determined or can be reasonably obtained, new construction and substantial improvement of any residential structure shall have the finished floor elevation of the lowest floor, including basement, elevated two feet or more above the base flood elevation. Mechanical equipment and utilities shall be w...
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