Showing ordinances that apply to Mirrormont, WA
Mirrormont is an unincorporated community (population 3,858) in King County, Washington. Because Mirrormont is not an incorporated city, it does not have its own municipal code. Instead, King County ordinances apply directly to properties here. The stormwater management rules below are the ones that govern your area.
Stormwater in King County is regulated under KCC 9.04 and the Surface Water Design Manual. Projects adding 2,000 sq ft of impervious surface or clearing 7,000 sq ft trigger review. NPDES MS4 permit applies.
King County operates under a federal NPDES Municipal Separate Storm Sewer System (MS4) permit (Phase I) issued by the Washington Department of Ecology under the Clean Water Act. This permit requires the county to prevent pollutants from entering Puget Sound, Lake Washington, salmon streams, and other waters through its storm drain system. Implementation is through KCC 9.04 (Surface Water Runoff Policy) and the King County Surface Water Design Manual (most recently updated 2021). Any project that creates or replaces 2,000 square feet or more of impervious surface, or clears 7,000 square feet or more of native vegetation, triggers stormwater review and design requirements. Small Parcel Best Management Practices apply to smaller projects. Flow control (detention) is required to prevent downstream flooding and erosion — new development must match predeveloped (forested) flow durations. Water quality treatment is required for pollution-generating surfaces — parking lots, high-use driveways, and commercial surfaces must treat runoff through biofiltration, wet ponds, or approved proprietary devices. Illicit discharges to the storm system are prohibited under KCC 9.12 — discharges of anything other than clean stormwater including soap, oil, sediment, paint, pet waste, and chemicals violate federal and state law. Construction sites must implement erosion and sediment controls. Agricultural operations have Best Management Practices under the King Conservation District. Critical aquifer recharge areas (KCC 21A.24) impose additional treatment requirements.
Stormwater violations carry civil penalties up to 10,000 dollars per day under KCC 9.12 and federal CWA penalties up to 25,000 dollars per day. Illicit discharges trigger immediate cleanup orders. Construction site stormwater violations face stop-work orders and restoration requirements.
See how Mirrormont's stormwater management rules stack up against other locations.
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