Auburn, WA Environmental Rules: Grading & Drainage (2026)

Grading and drainage in Auburn are regulated through ACC Title 15 construction code clearing and grading provisions, the building code's Chapter on grading, and the Department of Ecology Stormwater Manual for Western Washington. A clearing and grading permit is generally required when a project cuts or fills more than 50 cubic yards of earth, disturbs more than 7,000 square feet, places structural fill, or regrades areas near critical slopes or streams. Permit applications include a grading plan, drainage report, TESC plan, and geotechnical analysis for steep-slope or landslide-prone parcels. Auburn includes mapped erosion hazard, landslide hazard, and seismic hazard areas that trigger enhanced review, particularly along the West Hill bluff overlooking the Green River Valley and Lea Hill. Downhill property owners are protected from increased runoff; new sites must match pre-development flow durations and discharge in a controlled, non-erosive manner. Roof and footing drains must be tightlined to an approved discharge point rather than surface-released onto neighboring property. Violations of grading rules can trigger stop-work orders, civil penalties under ACC 1.25, and required restoration. Homeowners undertaking rockeries, retaining walls over 4 feet, or hillside patios should contact Auburn Community Development at (253) 931-3020 to confirm the permit pathway.