Environmental Rules in Colorado (2026)

Colorado administers stormwater discharge permits statewide through the Colorado Discharge Permit System, requiring…

Longmont bans any non-stormwater discharge into its municipal storm sewer system, covering hazardous chemicals…

Adams County's MS4 illicit discharge ordinance bans putting anything but rainwater into the county's storm drains…

Fort Collins bans dumping pollutants or contaminated water into streets, watercourses or the storm drainage system…

Fountain, Colorado's Stormwater Quality Management and Discharge Control Code bans discharging anything but stormwater…

Manitou Springs operates under an MS4 stormwater discharge permit that Colorado issued the city in 2003, and Title 14…

Westminster requires erosion and sediment controls on any land-disturbing activity and bans illicit discharges into its…

In unincorporated Arapahoe County, every detention pond, bioretention facility, sand filter, grass swale and major…

Arvada regulates its municipal separate storm sewer system (MS4) under Chapter 50, Article II, making it unlawful to…

Aurora requires a storm drainage system utility permit and a stormwater quality discharge permit from Aurora Water…

Boulder requires an erosion control permit before any ground-disturbing construction and a city-approved final drainage…

Boulder County Public Health bans discharging anything but stormwater into the county's storm drainage system or…

Centennial bans discharging pollutants into the storm drain system or watercourses, with limited exemptions for clean…

Colorado Springs bans any non-stormwater discharge into the City's municipal storm sewer system (MS4) under its…

Before Denver issues a building permit, developers must submit a detailed storm drainage plan to the manager of…

New development in unincorporated Douglas County must submit a grading and drainage plan under Zoning Resolution §…

El Paso County requires every land division's drainage facilities to preserve historical flow patterns, avoid flooding…

Greeley requires permanent stormwater water-quality control measures for new development disturbing an acre or more…

Lakewood, Colorado bans discharging polluting materials into its municipal storm sewer system and requires a Stormwater…

Littleton will not issue a construction, redevelopment, grading, or occupancy permit until the site meets the Littleton…

Loveland's stormwater utility, created under Chapter 13.18 of the Municipal Code, designs, builds, and maintains the…

Pueblo requires developers of sites disturbing an acre or more to build permanent stormwater quality best management…

Thornton requires a stormwater quality permit before disturbing more than one acre of land, City Code Section 22-115…

Weld County bans dumping anything but stormwater into its municipal storm sewer system, and requires construction sites…

Under C.R.S. § 25-8-501, any construction site disturbing one acre or more must obtain a CDPS stormwater discharge…

Private grading that disturbs one acre or more, is part of a larger project disturbing an acre or more, touches an open…

Every clearing, grading, or land-disturbance project in unincorporated Douglas County must comply with the county's…

Construction disturbing one acre or more in Longmont requires a stormwater construction activity permit, with a site…

Manitou Springs requires a Grading and Erosion Control Permit before any land disturbance tied to applicable…

Construction sites in unincorporated Adams County must control erosion and sediment with Best Management Practices…

Unincorporated Arapahoe County requires a Grading, Erosion and Sediment Control (GESC) permit before any regulated land…

Any land disturbance of 0.5 acres or more in Arvada needs a site disturbance permit under Section 50-51, backed by an…

Aurora requires an approved grading and drainage plan before earthwork begins, with rough grading tied to temporary…

Before breaking ground, Boulder requires an erosion control permit under Section 11-5-6: no one may commence…

Any land-disturbing activity in Centennial needs a Grading, Erosion, and Sediment Control permit issued by SEMSWA…

Denver caps how much you can re-grade a lot near the street or side yard: no more than a 1-foot difference between…

El Paso County bars clearing, grading, excavation, or filling on land disturbances over one acre until the county…

Fort Collins requires a Stockpiling Permit before fill dirt is placed on property that isn't already covered by an…

Fountain, Colorado, in El Paso County requires a grading permit before any land in the city is graded, stripped…

Greeley requires a city grading permit for land-disturbing work of one acre or more, smaller sites that are part of a…

Lakewood requires a grading permit from the Planning and Public Works Directors before any excavation, fill, or…

Littleton requires a Grading Permit before any grading, land-disturbing activity, or alteration of land begins…

Loveland requires a Stormwater Quality Permit from the city's Public Works Department before any land disturbance of…

Mesa County requires a Local Stormwater Construction Permit under LDC Section 8.22 for any development that disturbs…

Pueblo requires owners and operators of construction sites disturbing an acre or more to run erosion and sediment…

Under City Code Section 22-156(5), anyone holding a Thornton grading or stormwater quality permit must stop sediment…

Any construction site in unincorporated Weld County that disturbs one acre or more of ground needs a Grading Permit…

Westminster requires erosion and sediment controls on every land-disturbing project under Chapter 11 of Title VIII. Any…

Colorado's Water Conservation Board is the state authority that designates and approves storm and floodwater runoff…

Centennial bans new residential and non-residential construction in mapped floodplains outright, and allows any other…

Colorado Springs participates in the National Flood Insurance Program and regulates development in all FEMA-designated…

Unincorporated Arapahoe County bars new construction, fill and other development inside an adopted regulatory floodway…

Arvada requires a Floodplain Development Permit before any construction, fill, or storage of materials in a Special…

In Aurora, Colorado, all development in a mapped Special Flood Hazard Area is prohibited unless the floodplain…

No one may build in Boulder's one-hundred-year floodplain without a floodplain development permit under Section 9-3-6…

Denver requires new construction and substantial improvements inside its regulatory floodplain to elevate the lowest…

Douglas County bans new structures, storage yards and junkyards outright inside its mapped Floodplain Overlay District…

El Paso County requires a permit before any development in designated floodplain natural hazard areas in the…

Fort Collins requires a floodplain use permit from the Utilities Executive Director before any construction or…

Any construction or development within Greeley's mapped floodplain overlay district, from grading to new buildings…

Littleton bars solid waste facilities, outdoor storage and habitable structures in its flood fringe, prohibits any…

Any grading, filling, dredging, utility work, or construction inside Loveland's Floodplain Overlay Zone needs a City…

Unincorporated Mesa County requires a Floodplain Development Permit before any land disturbance, construction, or…

Thornton requires a floodplain development permit under City Code Section 22-312 before any construction or development…

Westminster requires a floodplain development permit for any construction in a special flood hazard area, bars storage…

Unincorporated Adams County regulates construction in flood hazard areas through Section 1612.3 of its Building Code…

Fountain requires a development permit from the floodplain administrator before any construction, grading, filling…

Lakewood regulates development in mapped flood hazard areas under its Flood Plain Management Ordinance, adopting the…

Longmont Municipal Code section 20.12.030 requires a floodplain development permit before any building, fill, or…

Any development proposed within a Manitou Springs floodplain must avoid or mitigate flood risk and pass review by the…

Pueblo requires a Floodplain Development Permit for any construction in FEMA-mapped Special Flood Hazard Areas within…

Building, filling, or altering land anywhere inside Weld County's FEMA-mapped 100-year floodplain requires a Floodplain…

Douglas County defines defensible space as the treated buffer around a structure where wildfire-carrying vegetation has…

Adams County's wildfire code requires a noncombustible ring of hard-surface materials, such as rock, gravel, sand…

Every structure in unincorporated Arapahoe County must keep a noncombustible buffer: gravel or crushed rock at least…

Boulder's Wildland Code requires new buildings in mapped wildland-urban interface areas to keep a modified, maintained…

In Colorado Springs' wildland urban interface risk areas, Appendix K to the fire code splits every parcel into a 0-5…

El Paso County requires landowners in Wildland Fire Areas to clear and maintain defensible space around structures…

Manitou Springs requires structures flagged at rapid wildfire risk to keep three defensible space rings: a five-foot…

Mesa County's Land Development Code sets a slope-based defensible space zone around new homes on wooded or brush land…

Fort Collins adopted the state's 2025 Colorado Wildfire Resiliency Code but stripped out every base-code section that…

In unincorporated Arapahoe County, engine idling at a permitted Oil and Gas Facility must be minimized at all times…

Arvada bars idling any vehicle over 10,000 pounds gross weight, or its attached auxiliary equipment such as a…

Aurora's Unified Development Ordinance caps idling of diesel and other stationary vehicle engines at 15 minutes per…

Fountain's Section 9.52.050 bans idling any stationary vehicle's engine, diesel or otherwise, for more than 15…

In Greeley, an unattended vehicle, one that hasn't moved and has no licensed driver in it, cannot idle more than 20…

New homes and substantial improvements in Arvada's Regulatory Floodplain must set the lowest floor, including the…

Unincorporated Arapahoe County requires a minimum two feet of freeboard above the 100-year base flood elevation for the…

Aurora requires new homes in mapped floodplains to sit two feet above base flood elevation, and new commercial…

Boulder does not stop at the base flood elevation: Section 9-16-1 defines a "flood protection elevation" that adds two…

Substantially improved structures in a Centennial floodplain must elevate their lowest floor at least two feet above…

Colorado Springs applies Regional Building Code Section 313's floodplain rules through UDC § 7.4.802, requiring every…

Denver requires new and substantially improved residential structures in the flood storage area to elevate their lowest…

Douglas County requires new construction and substantial improvements in the Floodplain Overlay District to elevate the…

El Paso County subdivision plats must show approved base flood elevation data and 100-year floodplain boundaries, with…

Fort Collins requires the lowest floor and all mechanical equipment of new construction, additions, substantial…

Fountain requires new and substantially improved residential structures in a mapped flood hazard area to elevate the…

Greeley requires new and substantially improved buildings in mapped flood hazard areas to elevate the lowest floor and…

In Lakewood flood plain areas with known base flood elevations, new construction and substantial improvements must have…

Littleton requires a minimum one-foot freeboard clearance between the base flood elevation and the lowest floor…

Longmont requires new and substantially improved residential structures in mapped flood zones to elevate the lowest…

New and substantially improved buildings in Loveland's floodway and flood fringe zoning districts must set their lowest…

New and substantially improved residential buildings in Mesa County's Special Flood Hazard Areas must set electrical…

Pueblo requires new and substantially improved buildings in flood zones to sit at least 1 foot above base flood…

New residential construction in a Thornton special flood hazard area must set its lowest floor at least one foot above…

New homes and additions in Weld County's mapped floodplain must sit a full foot above the base flood elevation, not…

Westminster requires new construction in a mapped floodplain to elevate the lowest floor one foot above the base flood…