McLean County, IL Environmental Rules: Stormwater Management (2026)
Key Facts
- Governing law
- McLean County Code Ch. 317, Art. VI
- Design storm
- Five-year-frequency storm event
- Enforcing officer
- McLean County Engineer
- Cure period
- 10 calendar days after written notice
- Coverage
- Unincorporated county subdivisions only
Summary
Unincorporated McLean County requires stormwater and erosion control measures on any subdivision needing public improvements, sized to hold sediment on-site through a five-year-frequency storm and coordinated with the developer's state NPDES permit.
All control measures required under this article shall conform to the design criteria, standards, and specifications provided in the Manual, now in effect or as hereafter amended. All control measures installed shall be sufficient to prevent sediment from leaving the permit site during a five-year-frequency storm event. The County Engineer may require additional control measures pursuant to the standards if determined as necessary after site inspection. A copy of the erosion control plan filed with the IEPA and a copy of the NPDES permit shall be furnished to the County Engineer.
Full Breakdown
Chapter 317, Article VI of the McLean County Code governs stormwater and erosion control for land divisions outside the cities of Bloomington and Normal. § 317-39 sets the technical bar: control measures must follow the design criteria in the County's Manual of Practice and must be sufficient to keep sediment on the permit site through a storm with a five-year recurrence interval. § 317-40 layers on maintenance duties: sediment and temporary stormwater controls must be built and working before any clearing, grading, stripping, excavation or fill begins, and they must stay functional until permanent ground cover and permanent stormwater controls are in place.
Any change to the approved plan needs the County Engineer's written sign-off first. This article sits inside the Subdivision of Land chapter, so it binds developers filing preliminary plans, final plats and planned unit developments, not existing built lots.
Violations & Fines
If the County Engineer finds the erosion or stormwater control plan isn't being followed, or that the installed measures aren't being maintained, the Engineer notifies the developer in writing. The developer then has 10 calendar days to fix the deficiency. Miss that window and the Engineer can place a stop-work order on the site, or do the corrective work directly and bill the developer's performance bond for the cost under § 317-35.
Frequently Asked Questions
Does McLean County's stormwater rule apply inside Bloomington or Normal?
What storm event must a McLean County stormwater plan handle?
What happens if a developer ignores a stormwater deficiency notice?
Sources & Official References
Other rules in McLean County
Compare McLean County to another location·View the Illinois environmental rules overview
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