Bothell, WA Environmental Rules: Erosion Control (2026)

Bothell Municipal Code § 18.05.090 is the surface water rule for grading chapter 18.05. All grading must meet the Bothell Design and Construction Standards, including the thresholds and minimum requirements of the King County Surface Water Design Manual, and must follow a city-approved erosion and sedimentation control plan. The director can add controls for specific sites based on site conditions, capacity limitations, significant erosion potential, landslide hazards, impacts to critical areas, or seasonal factors.

The permit trigger is in BMC 18.05.040: moving 50 cubic yards or more of earth, any grading in a critical area or buffer or in shoreline jurisdiction, any grade change of four feet or more, and grading in public rights-of-way or easements. Under BMC 18.05.050, even grading below those thresholds must install and maintain sediment and erosion control and pollution prevention best management practices. A grading permit application must include a temporary erosion and sedimentation control plan (TESCP), a drainage report, a storm water and drainage control plan, a surface water pollution prevention plan (SWPPP), and a street cleaning schedule covering the entire construction schedule. Plans involving more than 5,000 cubic yards of fill or excavation must be stamped by a Washington State licensed civil engineer (BMC 18.05.080). Pregrading before approvals is prohibited (BMC 18.05.060).

Slopes must be stabilized after cut or excavation operations cease, and cut surfaces cannot be steeper than one unit vertical to three units horizontal, or a 33 percent slope, without director approval (BMC 18.05.100). Under BMC 18.05.150 the director can suspend work during inclement weather or the entire wet season, can order work stopped outside the wet season for inadequate temporary controls, and lifts the order once a revised plan is approved and implemented. Grading permits expire two years from issuance (BMC 18.05.130).