Bonner County, ID Environmental Rules: Erosion Control (2026)

Subchapter 7.2 of Title 12 protects property, surface water and groundwater against soil erosion, sedimentation and stormwater runoff. Under § 12-720.2 it covers new subdivisions, commercial and industrial site development, public projects, new building construction within three hundred feet (300') of a lake, slough, pond, river, stream or intermittent stream, new construction on or within 300 feet of a slope of fifteen percent (15%) or more, and any excavation of more than fifty (50) cubic yards. Section 12-722.5 sorts the plan type by volume. Away from water and steep slopes, fill, grading or excavation between 50 and 100 cubic yards needs no plan, 100 to 500 cubic yards needs a grading/erosion plan, and over 500 cubic yards needs a grading/stormwater plan.

Within 300 feet of water or a 15 percent slope, even more than 50 but less than 100 cubic yards needs a grading/erosion plan, and 100 cubic yards or more needs a grading/stormwater plan. Under § 12-724.2 the erosion plan must include drawings at no more than one inch to one hundred feet, temporary and permanent erosion and sedimentation control locations, a construction and revegetation schedule, maintenance and repair responsibility, and impervious surface and retention basin calculations. The Planning Director reviews the plan and gives written approval, which expires if the use has not started within two (2) years.

Section 12-723.1 caps cut and fill slopes at two horizontal to one vertical unless a design professional shows steeper is feasible, and requires terracing on slopes over fifty feet (50') high. Section 12-727.1 requires at least one inspection for a grading/erosion plan, by the Planning Department or the permittee's design professional. Section 12-720.3 exempts, among others, traditional residential activities such as gardening, yard maintenance and snow removal.