Environmental Rules in Grays Harbor County, WA (2026)
4 rules for unincorporated Grays Harbor County, Washington.
Verified from official government sources
Stormwater Management
Every long subdivision approved in unincorporated Grays Harbor County must include a drainage plan that meets the state Department of Ecology's Stormwater Management Manual for Western Washington. Section 16.20.210 requires the plan to prevent erosion, flooding, and sedimentation through both construction and full build-out, keep storm drainage separate from sanitary sewers, and get public works division approval before the plat is final.
Grays Harbor County Subdivision Stormwater Rules
Some RestrictionsGrays Harbor County Code § 16.20.210
Subdivisions shall make adequate provisions for storm water or flood water runoff to prevent erosion, flooding, sedimentation and flooding of ditches or streams, destruction of natural drainage channels, flooding of adjacent and downstream properties and other public hazards. The provisions apply to both the construction and fully developed phases of the subdivision. A.General Requirements. Dra...
Erosion Control
Unincorporated Grays Harbor County requires erosion and sediment control on every development in a mapped erosion or landslide hazard area. Stormwater and drainage work must follow the Stormwater Management Manual for Western Washington, disturbed soil must be stabilized with practices such as mulching and geotextiles, and grading is limited to the amount the project actually needs, under Grays Harbor County Code § 18.06.580.
Erosion and Sediment Control in Grays Harbor County
Some RestrictionsGrays Harbor County Code § 18.06.580(B),(F)
B.Uses, structures, and activities in erosion hazard areas shall meet the following performance standards:1.On-site stormwater and drainage development shall meet the requirements of the current edition of the Stormwater Management Manual for Western Washington.2.Minimize modification of the natural contour of slopes by conforming to the existing topography of the site. ... 8.Reduce clearing, g...
Flood Zones
In unincorporated Grays Harbor County, no one may build, fill, or place a manufactured home within a mapped special flood hazard area without a floodplain development permit under Grays Harbor County Code Section 18.06.480. Planning and Building administers the rule against FEMA's Flood Insurance Study and Flood Insurance Rate Maps, and new floors generally must sit at least one foot above the base flood elevation.
Floodplain Development Permits in Grays Harbor County
Significant RestrictionsGrays Harbor County Code § 18.06.480
A permit shall be obtained before construction or development begins within any area of special flood hazard established in Chapter 18.06. Such permit is required for all structures, including manufactured homes and for all development including fill and other activities, as set forth in this title. ... The applicant shall be responsible for the costs of providing the required information, incl...
Flood Elevation Requirements
In unincorporated Grays Harbor County, new construction and substantial improvements inside a mapped special flood hazard area must have the lowest floor, including any basement, elevated one foot or more above the base flood elevation. Manufactured homes get the same one-foot freeboard on a permanent, anchored foundation. A development permit from Planning and Building must be obtained before construction starts, with elevation certified by a licensed engineer or architect, under Grays Harbor County Code § 18.06.500.
Flood Elevation Rules in Grays Harbor County
Some RestrictionsGrays Harbor County Code § 18.06.500(F)
F.Elevation standards for residential structures.1.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 lowest floor, including basement, elevated one foot or more above the BFE. Mechanical equipment and utilities shall be elevated at least one foot a...
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