Environmental Rules in Idaho (2026)

New development in unincorporated Ada County must submit an engineer-prepared drainage study and drainage plan under…

In unincorporated Bannock County, new development cannot increase peak stormwater flow onto downstream neighbors beyond…

Boise regulates stormwater discharge and requires drainage plans for new development under its Stormwater Management…

Development in unincorporated Bonner County, Idaho must handle a 25 year design storm, hold and treat the first…

Bonneville County requires runoff from impervious surfaces to be retained on-site, with lots designed to hold a…

Any Caldwell development disturbing one acre or more must have a Stormwater Pollution Prevention Plan approved by the…

Canyon County requires every preliminary plat filed for a subdivision in unincorporated Canyon County, Idaho to state…

In the City of Coeur d'Alene, every land disturbing activity needs an approved stormwater management plan, and runoff…

Idaho Falls' Chapter 8-14 sets stormwater management objectives for construction sites, requiring measures that protect…

Unincorporated Kootenai County requires a site disturbance permit for new driveways, subdivisions, and most grading or…

Every new development in Meridian must install an adequate storm drainage system built to the city's adopted standards…

Nampa bans dumping pollutants into its municipal storm drain system and enforces the city's federal NPDES stormwater…

Pocatello's stormwater chapter applies to every new development or redevelopment site in the city, covering grading…

Any land divided into a subdivision in unincorporated Twin Falls County must be graded to handle its own storm water…

Construction on Ada County Hillside Overlay sites, meaning any grading on a slope of 25 percent or more, must meet…

Before Bannock County will approve a conditional use permit on land with an average slope over 10 percent, the…

Boise requires a grading permit under the city's building code before altering land contours, unless the work falls…

In unincorporated Bonner County, Idaho, grading and excavation of more than 50 cubic yards triggers a written…

Anyone disturbing ground in a Bonneville County right-of-way must get a permit from the County Weed Department first…

Any construction or land-disturbing project affecting one acre or more inside Caldwell city limits must obtain a…

In the City of Coeur d'Alene, an erosion, sediment and construction waste control plan must be approved before any site…

Idaho Falls requires an approved erosion control plan for construction activity, and site erosion, sediment, or…

Kootenai County requires a site disturbance permit for grading, excavation and new driveways outside the cities, with…

Every new development in Meridian must include an adequate storm drainage system built to the city's adopted standards…

Nampa requires a site development/erosion and sediment control permit for any land-disturbing construction activity…

Every construction project in the City of Pocatello needs an erosion control permit before work begins, under Section…

Twin Falls County's only sediment-control mandate sits in its energy production chapter: anyone building a solar or…

Idaho Code 46-1020 through 46-1024 establishes the statewide framework directing local governments to adopt floodplain…

Ada County requires a floodplain development permit for any construction, grading, filling or fencing within Special…

Caldwell's FP-1 Floodplain Overlay Zone covers FEMA-designated flood hazard areas along the Boise River and requires a…

Before anyone can grade, fill, build or otherwise develop land inside a mapped special flood hazard area in…

Building, filling, grading or substantially improving property inside a FEMA-mapped special flood hazard area in…

Meridian requires a floodplain development permit and elevation two feet above base flood elevation for any…

Nampa requires a floodplain development permit before any construction, fill, or land alteration in a mapped special…

Any development inside a special flood hazard area in Pocatello needs a floodplain development permit before work…

In unincorporated Bannock County, any development activity within a special flood hazard area requires a floodplain…

Boise requires new and substantially improved homes in the Floodway Fringe to elevate the lowest floor, including…

In unincorporated Bonner County, Idaho, no one starts development inside a Special Flood Hazard Area without a…

Bonneville County regulates building in areas the Federal Insurance Administrator has mapped as special flood hazard…

In the City of Coeur d'Alene, Idaho, any development inside a FEMA special flood hazard area needs a floodplain…

Idaho Falls requires a Floodplain Development Permit before any development activity starts in a Special Flood Hazard…

Twin Falls County requires a development permit before any construction, fill, or land disturbance begins within an…

In unincorporated Bonner County, Idaho, community docks and marinas with upland accommodations need a conditional use…

Caldwell treats docks, piers, boat ramps and marinas as floodway obstructions: any such structure with the potential to…

A boat dock counts as regulated development under Bonneville County's floodplain chapter. Building or altering one…

Kootenai County's land use code does not permit a private boat dock itself; that requires a separate Idaho Department…

Any new construction or alteration of a habitable structure inside Ada County's Wildland-Urban Interface Overlay…

Boise requires a 30-foot defensible space around homes in designated Wildland-Urban Interface areas, with a 5-foot…

In unincorporated Bonner County, Idaho, every proposed lot in a subdivision must be designed with a fire protection…

Wildfire mitigation plans for timbered subdivisions in unincorporated Kootenai County must identify emergency…

On sloped Pocatello building sites, section 17.05.140(A)(6) requires native vegetation to stay in place, even inside…

New and substantially improved buildings inside an Ada County Special Flood Hazard Area must set their lowest floor at…

In unincorporated Bannock County, new residential construction in a mapped flood hazard area must have its lowest floor…

Boise requires new and substantially improved homes in the Floodway Fringe to elevate their lowest floor, including…

In unincorporated Bonner County, Idaho, new and substantially improved residential and non-residential buildings in a…

Bonneville County adds a one-foot safety margin above the base flood elevation for construction in mapped flood hazard…

Caldwell's floodplain ordinance requires new residential construction in a mapped special flood hazard area to elevate…

Unincorporated Canyon County, Idaho requires one foot of freeboard above the base flood elevation before it will…

In the City of Coeur d'Alene the flood protection elevation equals the base flood elevation plus the floodway…

Idaho Falls sets the Flood Protection Elevation at the Base Flood Elevation plus 1.5 feet of freeboard, and new…

Kootenai County requires three feet of freeboard above the base flood elevation for every new or substantially improved…

In Meridian's mapped floodplain, new construction and substantial improvements must elevate the lowest floor at least…

Nampa requires new and substantially improved residential structures in flood hazard areas to elevate their lowest…

In the City of Pocatello, new construction and substantial improvements in special flood hazard areas must have the…

New homes and additions in Twin Falls County's flood hazard areas must sit at least one foot above the base flood…