Environmental Rules in Washington (2026)

Washington Department of Ecology administers federally-required NPDES stormwater permits statewide, setting minimum…

Auburn follows the Department of Ecology Western Washington Stormwater Manual through ACC Title 13 surface water code…

Bellingham requires city approval under BMC Ch. 15.42 before any new development, redevelopment, or land-disturbing…

Federal Way bans dumping contaminants into surface water, stormwater or groundwater citywide and sets numeric…

Kirkland requires a drainage permit before any project adding 500 square feet or more of new impervious surface…

Unincorporated Kitsap County requires a site development activity permit before any construction that involves…

Renton regulates surface water runoff and drainage under RMC 4-6-030, requiring drainage review for development…

Sammamish requires erosion and sediment control on any land-disturbing activity, whether or not it needs a clearing and…

Whatcom County bans illicit discharges into its municipal storm sewer system (MS4) in unincorporated areas under WCC…

Bellevue requires a drainage connection permit before any property connects to or modifies the public storm and surface…

New development in the unincorporated, non-urbanized area of Cowlitz County that adds 12,000 square feet or more of…

Edmonds regulates stormwater runoff from construction and development under ECDC 18.30, the city's Stormwater…

Everett requires stormwater drainage review for any project adding 2,000+ square feet of new or replaced hard surface…

In unincorporated Franklin County, all storm drainage generated by new development must stay on the site. Franklin…

In unincorporated Grant County, new development must control stormwater runoff so it does not harm neighboring land…

Kennewick requires new development to design stormwater facilities under the state's Stormwater Management Manual for…

Kent requires a permit before anyone constructs, installs, modifies or places any storm or surface water drainage…

Unincorporated King County requires drainage review and stormwater control facilities once a project hits set…

Lakewood requires every new development and redevelopment project to install an approved stormwater management system…

Lynnwood requires a stormwater permit and site plan for projects disturbing 2,000 square feet or more of land or adding…

Marysville adopts the state's 2019 Stormwater Management Manual for Western Washington as its own minimum drainage…

Pasco runs a storm water management utility under Chapter 13.80 PMC that charges monthly fees by parcel type, from…

Pierce County funds its stormwater system through a Storm Drainage and Surface Water Management Utility under PCC…

Port Townsend requires all developments to meet Washington's 2005 Stormwater Management Manual for Western Washington…

Every development, redevelopment, and construction project in Puyallup must follow the Washington Department of…

Seattle's Stormwater Code requires every development project to maintain natural drainage patterns and prevent adverse…

SCC Chapter 14.32 requires a project permit before new development or redevelopment breaks ground in unincorporated…

Unincorporated Snohomish County requires a stormwater site plan and drainage review once a project adds 2,000 square…

Spokane County charges every developed parcel in unincorporated areas an annual stormwater service fee based on…

Spokane Valley regulates stormwater under SVMC Chapter 22.150. Grading over 500 cubic yards, new impervious surface…

Tacoma requires everyone discharging stormwater or pollutants into the municipal stormwater system or receiving waters…

Thurston County regulates stormwater and erosion through the county's Drainage Design and Erosion Control Manual…

New development or redevelopment in Yakima that disturbs one acre or more must submit a stormwater site plan and…

Any land-disturbing project of one acre or more in unincorporated Yakima County, or a smaller phase of a larger…

Washington makes it unlawful under RCW 90.48.080 to discharge sediment or other polluting matter into state waters, and…

Auburn requires a Construction Stormwater Pollution Prevention Plan for any project that disturbs land, spelling out…

Bellevue requires a Construction Stormwater Pollution Prevention Plan (CSWPPP) for clearing, grading and…

All grading citywide in Bellingham must include erosion containment, and any land-disturbing work proposed between…

Land-disturbing work in Benton County requires erosion and sediment control, and the arid, windy climate adds a…

Anyone grading land in unincorporated Cowlitz County must install erosion control structures before work starts and…

Edmonds requires a construction stormwater pollution prevention plan (SWPPP) under ECDC 18.30.060(D)(2) for any project…

Everett requires a city-approved grading plan before any site work disturbs natural features, under Everett Municipal…

FWRC 7.05.020 makes it a public nuisance and code violation for a property owner to allow erosion, undermining, or…

Unincorporated Franklin County has no stand-alone grading and erosion ordinance; erosion control comes through SEPA…

Grant County requires all clearing, grading, and development to control erosion and stormwater under UDO § 23.12.080…

Kennewick requires a Land Use Clearing and Grading Permit for excavation or grading work, but exempts small jobs -- up…

Kent adopts Appendix J of the International Building Code, the grading and erosion-control appendix, and puts the…

King County requires erosion and sediment control on every clearing or grading site, with stricter seasonal limits from…

Kirkland's zoning code makes it a violation for a property owner to let construction or site conditions erode…

Unincorporated Kitsap County caps artificial slopes at a 2:1 gradient unless a professional engineer proves a steeper…

Every Lakewood project that clears, grades or otherwise disturbs a site must use erosion and sediment control best…

Lynnwood requires a temporary erosion and sediment control plan, plus a vegetation management and restoration plan, for…

Marysville requires a clearing and grading permit before moving 50 or more cubic yards of fill and cut, clearing over…

Every site development permit in unincorporated Pierce County carries a Reclamation Guarantee under PCC 17A.20.020 that…

Port Townsend requires construction sites to follow the state stormwater manual's erosion control standards, with…

No one may clear, grade, or fill land in Puyallup without first obtaining a clearing, filling and grading permit and…

RMC 4-4-060.D requires anyone who clears, grades, or disturbs a site to control erosion and sediment so runoff doesn't…

Sammamish requires erosion and sediment control on every site that is cleared or graded, whether a permit is needed or…

Seattle grading permits require erosion control from cut and fill slopes and cleared areas, per SMC 22.170.070. SDCI…

In unincorporated Skagit County, SCC 14.32.130 requires every development project to control erosion and sedimentation…

Unincorporated Snohomish County requires every new development and redevelopment project, regardless of size, to…

Spokane County requires a stormwater pollution prevention plan and erosion and sediment control best management…

Spokane Valley requires an engineered grading permit, and with it a temporary erosion and sediment control (TESC) plan…

Tacoma requires a Construction SWPPP for projects adding 2,000 square feet of impervious surface or disturbing 7,000…

Thurston County requires construction and site development to follow its 2022 Drainage Design and Erosion Control…

Whatcom County bans land-disturbing clearing over 500 square feet from October 1 through May 31 under WCC § 20.51.410…

Yakima requires a grading permit for most excavation and fill work under its adopted building code, but exempts small…

Washington's Growth Management Act, not a home-grown Yakima County ordinance, is why erosion and other geologic hazards…

Pasco requires every portion of a lot not landscaped or covered by improvements to be maintained so it controls erosion…

Washington's Shoreline Management Act (RCW 90.58) requires Shoreline Substantial Development Permits for most…

Benton County has no ocean coast, but the Columbia and Yakima rivers are shorelines of the state. Under the Shoreline…

Whatcom County's Salish Sea shoreline, Bellingham Bay, Lake Whatcom, and the Nooksack River are shorelines of the…

Any dock, bulkhead, shoreline armoring, or structure built within shoreline jurisdiction of the Yakima River, Naches…

Washington requires all communities participating in the National Flood Insurance Program to adopt floodplain…

Auburn regulates construction in FEMA-mapped Zone AE floodplains along the Green River and White River under ACC Title…

Benton County enforces floodplain rules along the Columbia and Yakima rivers. In FEMA Special Flood Hazard Areas, new…

Whatcom County enforces floodplain rules along the flood-prone Nooksack River. In FEMA Special Flood Hazard Areas, new…

Federal Way requires a floodplain development permit under FWRC 19.142.060 before any construction, fill, or…

Kent requires a flood zone development permit (REFZ) before any construction, substantial improvement, or manufactured…

Renton bans new construction, fill, and residential rebuilding inside designated floodways unless narrow encroachment…

Sammamish requires a development permit before any construction, fill, grading or other development begins in a mapped…

A floodplain project permit is required before any construction or development in a special flood hazard area in…

Any development inside a mapped special flood hazard area in unincorporated Snohomish County needs a flood hazard…

Thurston County requires any development in a designated floodplain or flood hazard area to go through the county's…

Yakima adopts FEMA's Flood Insurance Study and rate maps for Yakima County by reference, requiring a city-approved…

Washington state law bars new or rebuilt residential structures inside designated floodways, and Yakima County's own…

Bellevue amends the International Building Code to require that construction in flood hazard areas follow the FEMA…

Bellingham requires new and substantially improved residential structures in FEMA-mapped flood hazard areas to have the…

In unincorporated Cowlitz County, any construction or development within a mapped special flood hazard area needs a…

Any construction or development within an Edmonds special flood hazard area needs a floodplain development permit…

Everett requires a floodplain development permit before any construction or fill begins in a mapped special flood…

Building or altering anything within a mapped special flood hazard area in unincorporated Franklin County requires a…

Any construction or development inside a mapped special flood hazard area in unincorporated Grant County needs a…

Before any construction or land-disturbing development begins within a Kennewick area of special flood hazard, KMC…

Unincorporated King County requires a floodplain development permit before any new construction, fill, or substantial…

Any construction or fill in a Kirkland special flood hazard area needs a development permit under KMC 21.56.055, plus a…

In unincorporated Kitsap County, no one may build, fill, or alter land in a mapped special flood hazard area without a…

Lakewood, Washington requires a floodplain development agreement before any construction, fill, or land alteration…

Lynnwood regulates all areas of special flood hazard under LMC Chapter 16.46, adopted from FEMA's Snohomish County…

Marysville requires a development permit before any construction, fill, or other development begins within a mapped…

Pasco requires a development permit before any construction, fill, or manufactured home placement begins in a mapped…

In unincorporated Pierce County, no one may start development or a regulated activity within a mapped flood hazard area…

Any construction or development in Port Townsend's special flood hazard area needs a floodplain development permit…

Puyallup requires a development permit before any construction, fill, or land change in a mapped area of special flood…

Seattle requires a floodplain development permit before any construction, fill, or substantial improvement in…

Any development, structure, manufactured home, fill or work placed within a mapped area of special flood hazard in…

Spokane Valley requires a development permit before any construction, fill, or land alteration begins within a mapped…

Tacoma requires a recorded Notice on Title for any property with land in the 100-year floodplain or Riparian Buffer…

Seawall and bulkhead maintenance in Seattle is regulated under the Shoreline Master Program (SMC 23.60A) and the…

Installing or modifying boat docks in Seattle requires permits under the Shoreline Master Program (SMC 23.60A), federal…

Kent's critical areas code bars building a dock, deck, or other structure inside the buffer around any regulated lake…

Unincorporated King County limits shoreline docks to water-dependent uses, caps most residential lots to one dock or…

Kitsap County requires a Shoreline Substantial Development Permit for new docks, piers, floats, and mooring buoys…

Pasco regulates every dock, pier, or mooring buoy on the Columbia and Snake rivers under its Shoreline Master Program…

New docks, piers, and marinas in Port Townsend need a zoning and critical-area permit, and are barred from critical…

Thurston County bans new boat launching ramps, piers, docks and floats in estuarine wetlands and Category I wetlands…

Whatcom County zones private, noncommercial boat docks by shoreline type: on a manmade canal built for boat traffic…

Bellingham exempts small private docks from a shoreline permit, but larger docks need a shoreline substantial…

Edmonds regulates private docks, piers and floats through its Shoreline Master Program. A single-family dock is a…

Outside Everett's shoreline master program area, new docks are capped at 4 feet wide, 25 feet long and 5 feet high…

Federal Way regulates piers, docks, floats, and mooring buoys under its Shoreline Master Program. A single-family dock…

Kirkland limits waterfront property owners to one pier or dock per lot, capped at 480 square feet of surface coverage…

Waterfront owners on American Lake, Gravelly Lake, Lake Louise and Lake Steilacoom can build or replace a private dock…

Marysville caps private, noncommercial docks and boathouses at 20 feet high, 1,000 square feet of roof, and half the…

In unincorporated Pierce County, a private dock for a single-family or multi-family home skips the Shoreline…

Renton regulates new and expanded docks and piers under its Shoreline Master Program, RMC 4-3-090.E.7. Applicants must…

Snohomish County's Shoreline Management Program caps private dock length, width and boathouse size within shoreline…

Spokane Valley lets most private boat docks skip a full shoreline substantial development permit under SVMC §…

Any pier, wharf, dock or marina built in Tacoma falls under the city's Waterfront Structures and Marina Code, which…

Yakima's Shoreline Master Program caps private dock length at 8 feet from the ordinary high water mark on Aspen Lake…

Docks and piers within Yakima County's shoreline jurisdiction must be the minimum size needed for the use, and…

Unincorporated Spokane County lists floating docks, boat mooring, and buoys as uses permitted without county review…

Property owners in unincorporated Cowlitz County who use defensible space to satisfy fire-flow requirements must clear…

Where a proposed home in unincorporated Franklin County sits more than 500 feet from a working fire hydrant or approved…

Unincorporated King County lets property owners clear brush and prune trees for wildfire defensible space without a…

In unincorporated Kitsap County, a builder on a lot where water supply cannot deliver adequate fire flow can offset the…

Port Townsend adopted the 2021 International Wildland-Urban Interface Code by reference under PTMC 16.04.020(E)…

Spokane County requires wildfire defensible space only within rural cluster developments (RCDs), the county's…

Pierce County lets property owners clear wildfire defensible space within 30 feet of dwellings, outbuildings, barns and…

In unincorporated Cowlitz County, CCC § 10.25.040(B)(4) makes it a public noise disturbance to idle a stationary truck…

Port Townsend caps vehicle idling at three minutes citywide, with exceptions for traffic stops, extreme temperatures…

In unincorporated Snohomish County, running or idling a stationary truck over 10,000 pounds GVWR for more than ten…

Spokane Valley caps commercial vehicle idling in residential zones at 15 consecutive minutes, or 15 minutes total per…

Thurston County caps warm-up idling at 10 minutes for most vehicles and 20 minutes for commercial diesel vehicles under…

New homes and substantial improvements in Kennewick's mapped flood hazard areas must have the lowest floor built one…

In unincorporated Kitsap County's mapped special flood hazard areas, new or substantially improved residential…

In mapped AE and A1-30 flood zones, Sammamish Municipal Code 15.10.160 requires new residential construction and…

New homes and substantial improvements in a Skagit County special flood hazard area must have their lowest floor…

Auburn requires new construction in the Special Flood Hazard Area to be built to a flood protection elevation one foot…

Bellevue requires new residential construction in flood hazard areas to sit at least one foot above the base flood…

New and substantially improved homes in Bellingham's mapped flood hazard areas must elevate the lowest floor at least…

Benton County requires the lowest floor of any new or substantially improved residential structure in a mapped special…

New and substantially improved buildings in unincorporated Cowlitz County's mapped flood zones must sit above the base…

Edmonds requires two feet of freeboard above the base flood elevation for buildings in a Coastal High Hazard Area or…

New and substantially improved residential structures in Everett's AE and A1-30 flood zones must elevate the lowest…

Federal Way requires new and substantially improved residential structures in AE flood zones to elevate the lowest…

New and substantially improved homes in Franklin County's mapped flood zones must sit at least one foot above base…

New homes and substantial improvements built in Grant County's AE, A1-30, or other A-zone flood areas must sit at least…

Kent requires new construction and substantial improvements in special flood hazard areas to elevate the lowest floor…

Unincorporated King County requires new and substantially improved buildings in flood hazard areas to elevate the…

Kirkland requires new and substantially improved residential structures in special flood hazard areas to elevate the…

In Lakewood's Flood Hazard Overlay, new construction and substantial improvement of any residential structure must…

Lynnwood requires new and substantially improved residential structures in a mapped flood hazard area to have their…

New and substantially improved residential structures in Marysville's special flood hazard areas must have their lowest…

New and substantially improved homes in Pasco's mapped flood hazard areas must have their lowest floor, including any…

New construction and substantial improvements in a Pierce County flood hazard area must sit above the base flood…

Port Townsend requires new and substantially improved residential structures in flood hazard areas to elevate the…

New and substantially improved homes in Puyallup's flood hazard areas must have the lowest floor built at least one…

Renton requires new and substantially improved buildings in mapped flood hazard areas to raise the lowest floor at…

Seattle requires new construction in A-zone flood hazard areas to sit at least three feet above the base flood…

Unincorporated Snohomish County requires new and substantially improved buildings in mapped special flood hazard areas…

Spokane County requires new and substantially improved buildings in a mapped flood hazard area to sit at least one foot…

New residential construction in a Spokane Valley flood hazard area must elevate its lowest floor, including any…

Tacoma requires new critical facilities built in the mapped 100-year floodplain to elevate their lowest floor at least…

Thurston County requires two feet of freeboard above the base flood elevation for new construction and substantial…

In Whatcom County's mapped special flood hazard areas, the flood protection elevation is base flood elevation plus one…

Yakima requires new and substantially improved residential structures in mapped special flood hazard areas to elevate…

New homes and substantial improvements in Yakima County's mapped special flood hazard areas must sit at least one foot…