Environmental Rules in Idaho (2026)

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

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

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…

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…

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

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

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…

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…

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…

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

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

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

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…

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

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

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

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…

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…