Casper, WY Environmental Rules: Erosion Control (2026)

Casper Municipal Code section 12.20.030 makes it unlawful to "do any construction activity that disturbs areas one acre or greater in size within the corporate limits of the city" without first obtaining a permit from the community development office, unless the activity is exempt under section 12.20.040, which excludes single-family basement and footing excavation under a valid building permit, city-run projects, and de minimis disturbances. Applicants must submit an erosion and sedimentation control plan under section 12.20.065 identifying best management practices such as silt fencing, temporary seeding, sediment basins and inlet protection, and, for sites over five acres, must state whether a state NPDES stormwater permit has issued from the Wyoming Department of Environmental Quality.

Section 12.20.080(A) sets the required security at ten cents per square foot for the first one million square feet of disturbed area, rising to two and one-half times the estimated plan cost for larger sites, with a floor of $100,000 for permits over one million square feet and a minimum of $5,000 for any permit, plus liability insurance of $250,000 per claimant and $500,000 aggregate. Permits are issued or denied within fifteen calendar days under section 12.20.100(E) and expire if construction has not begun within one year. The city manager inspects sites under section 12.20.110 and can issue stop-work orders or revoke permits under section 12.20.140 for noncompliance.