Environmental Rules in McHenry County, IL (2026)
5 rules for unincorporated McHenry County, Illinois.
Verified from official government sources
Stormwater Management
McHenry County requires a stormwater management permit before any regulated development, land disturbing 5,000 square feet or more, work in a flood hazard area, or in a wetland, under the Stormwater Management Ordinance § 17.60.020. Violations run up to $750 per day, with a $100 court-cost floor.
McHenry County Stormwater Management Permit
Significant RestrictionsMcHenry County Code § 17.60.020
No person, firm, corporation or governmental agency, unless specifically exempted, shall commence any regulated development without first obtaining a stormwater management permit. Unless it is specifically exempted...any activity that meets any of the following criteria, is considered regulated development: a. Any development that is located partially or completely in a flood hazard area; or b....
Erosion Control
McHenry County's Stormwater Management Ordinance makes soil erosion and sediment control mandatory on every regulated construction site in the unincorporated county. Disturbed ground must get temporary stabilization within 1 working day of work stopping and be fully stabilized within 14 calendar days. The McHenry County Stormwater Coordinator enforces the rule and can fine violators up to $750 per day under § 17.60.090.
Erosion and Sediment Control Rules in McHenry County
Some RestrictionsMcHenry County Code § 17.60.060(A)(1)(h)
Stabilization of disturbed areas shall be initiated immediately whenever any clearing, grading, excavating or other earth disturbing activities have permanently ceased on any portion of the development site, or temporarily ceased on any portion of the development site and will not resume for a period exceeding 14 calendar days. Stabilization of disturbed areas shall be initiated within 1 workin...
Flood Zones
Unincorporated McHenry County adopts the International Building Code's flood-load rules, but routes every real standard, mapping and design requirement to the county's own Stormwater Management Ordinance and to ASCE 7 and ASCE 24, so a build in a flood hazard area answers to both codes together.
Building in McHenry County Flood Hazard Areas
Some RestrictionsMcHenry County Code § 15.04.010 (IBC §§ 1612.3, 1612.4, 1804.5, as amended)
1612.3 Establishment of flood hazard areas. The establishment of flood hazard areas shall comply with the McHenry County Stormwater Management Ordinance. ... 1612.4 Design and construction. The design and construction of buildings and structures located in flood hazard areas shall be in accordance with the McHenry County Stormwater Management Ordinance and Chapter 5 of ASCE 7 and ASCE 24. ... 1...
Boat Dock Permits
Unincorporated McHenry County requires a stormwater management permit before building a boat dock on the Fox River, Chain O'Lakes or any other regulated waterway. Docks qualify for the streamlined General Permit Number 1 in County Code § 17.60.030 only if they stay within strict size limits enforced by the county's Stormwater Management Enforcement Officer.
Boat Dock Permits in McHenry County
Some RestrictionsMcHenry County Code § 17.60.030(A)(3)(i)
i. Minor non-commercial boat docks – To be authorized by this General Permit Number 1, construction of minor non-commercial boat docks shall meet the following criteria. (1) The boat dock shall not project more than 50 feet into a waterway, and in no instance greater than ¼ of the width of the waterway. (2) The width of the boat dock shall not be greater than 10 feet. (3) For L-shaped o...
Flood Elevation Requirements
In unincorporated McHenry County, new buildings, additions and substantial improvements inside a mapped floodplain must reach a flood protection elevation (FPE) of at least two feet above base flood elevation (BFE). Attached garages and small accessory buildings need only 0.5 foot of freeboard above BFE. The County Stormwater Management Ordinance sets the standard and requires a FEMA elevation or floodproofing certificate before sign-off.
McHenry County Base Flood Elevation Freeboard Rule
Some RestrictionsMcHenry County Stormwater Management Ordinance § C.11 (Building Protection Standards for Flood Hazard Areas)
11. Building Protection Standards for Flood Hazard Areas. The following requirements apply to: all new buildings, building additions, and substantial improvements located within a floodplain; and to all new buildings and building additions in a flood prone area after December 1, 2014 that increase total enclosed area below the BFE by more than 600 square feet. These requirements apply to a bu...
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