St. Clair County, IL Environmental Rules: Erosion Control (2026)
Key Facts
- Permit trigger
- 1 acre disturbed or 10,000 sq ft impervious
- Permit trigger
- Within 25 ft of a channel or wetland
- Permit trigger
- Over 100 cubic yards of earth moved
- Issued by
- Building and Zoning Department
- Design standard
- Hold sediment through a 10-yr, 24-hr storm
- Exempt
- Approved farm conservation plans, road maintenance
Summary
Any new development or land-disturbing project in unincorporated St. Clair County that disturbs an acre or more, adds 10,000 square feet of impervious surface, moves more than 100 cubic yards of earth, or works within 25 feet of a stream or wetland needs a Stormwater Management and Erosion Control Permit from the Building and Zoning Department under Stormwater Control Code Sec. 33-1-3.
33-1-3 APPLICABILITY. This Code applies to all new development or redevelopment in the County... no person, firm or corporation... shall commence any development or redevelopment activities without first obtaining a Stormwater Management and Erosion Control Permit from the Building and Zoning Department. This Code shall apply to all new development and redevelopment in the County as set forth herein: (A) Any new development or redevelopment that will include an area that will meet or exceed ten thousand (10,000) square feet of total impervious surface (i.e., streets, roof, patio or parking area or any combination thereof); or that involves one (1) acre or more of land; (B) Any land disturbing activity... that will affect an area that will meet or exceed one (1) acre of land; or (C) ...any land disturbing activity, if the activity is within twenty-five (25) feet of any channel as defined in this Code including but not limited to any river, lake, pond, stream, sinkhole, or wetland; or (D) Projects involving land disturbing activity that will exceed one hundred (100) cubic yards.
Full Breakdown
Sec. 33-1-3 sets four independent triggers for the permit, any one of which brings a project under the Stormwater Control Code: 10,000 square feet or more of new impervious surface such as streets, roofs, patios or parking, or one acre or more of land involved; one acre or more of land-disturbing activity like clearing, grading, stripping, excavating or filling; any land-disturbing activity within 25 feet of a defined channel, including a river, lake, pond, stream, sinkhole or wetland; or a project moving more than 100 cubic yards of earth.
Sec. 33-4-47 lays out the design principles a permitted project must follow: erosion and sediment measures must keep sediment from leaving the site in a storm as small as a 10-year, 24-hour event, steep slopes greater than 3:1 are to be avoided where high cuts or fills would be needed, natural vegetation near watercourses and wetlands is to stay undisturbed wherever possible, sediment basins, traps and filter barriers must go in before clearing and grading starts, and no waste generated on site, including landscape waste, may be burned except through an Illinois EPA-permitted air curtain destructor.
Sec. 33-1-4 exempts routine agricultural crop production under an approved Farm Conservation Plan, maintenance of existing stormwater or erosion-control structures, and public road maintenance, though the exemption does not cover man-made changes to farmland made for something other than growing crops or an approved conservation practice.
Violations & Fines
Sec. 33-1-9 makes it unlawful to start development in the county without first securing a Stormwater Management and Erosion Control Permit, and separately unlawful to violate, disobey or resist enforcement of any permit condition once one is issued. New development and redevelopment covered by the Code must also meet NPDES General Permit No. ILR40 notice-of-intent requirements under Sec. 33-1-10, and enforcement runs through the county's standard zoning violation and penalty process for uncorrected conditions.
Frequently Asked Questions
What size project needs an erosion control permit in unincorporated St. Clair County?
Is farmland exempt from the erosion control permit?
Can I burn construction debris or land-clearing waste on site?
Sources & Official References
Other rules in St. Clair County
Compare St. Clair County to another location·View the Illinois environmental rules overview
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