Blue Earth County, MN Environmental Rules: Erosion Control (2026)

Section 24-304 is the operative erosion-control ordinance for development outside the county's cities. Subsection (a) adopts Minnesota's water-retention statutes, Minn. Stats. §§ 103B.301-103B.355, by reference, tying the county's program to the state watershed management framework. Subsection (b) sets the trigger for stormwater review: once new development covers or replaces vegetation with one acre or more of impervious surface, it cannot proceed without an approved stormwater management plan, though linear projects like sidewalks, paths, trails, and the repair, reconditioning or resurfacing of existing roads and impervious surfaces are specifically exempted.

Subsection (c) adds bluff-specific rules: no structure may be erected within 30 feet of the top of a bluff, and if the bluff is actively eroding the zoning administrator can require a licensed engineer's geotechnical report and increase the setback based on its findings; excavations for walk-out basements and impervious surfaces such as patios are flatly prohibited within any bluff impact zone. Subsection (d) requires erosion and siltation control measures to be coordinated with construction staging, limits how much land can be exposed at once, and caps soil exposure at 60 days unless the planning commission approves an extension.

Subsection (f) regulates fill volume directly: filling more than 500 cubic yards in the Agricultural and Country districts, or more than 50 cubic yards in the Rural Residence and Rural Townsite districts, requires an interim use permit unless the fill is tied to an approved septic system installation.