Environmental Rules in Winnebago County, IL (2026)
4 county-level rules, plus city-specific rules for 1 city in Winnebago County, Illinois.
Verified from official government sources
Stormwater Management
New development in unincorporated Winnebago County can't release stormwater runoff faster than the land could naturally drain before it was built on. County Code § 50-247(a)(2) caps the controlled release rate at 0.2 cubic feet per second per acre, the county's engineered limit for the downstream drainage system, enforced through the Surface Water Management Ordinance's permit process.
Winnebago County Stormwater Detention Rate Rule
Some RestrictionsWinnebago County Code § 50-247(a)(2)
Stormwater detention regulations. These regulations address escalation in flooding within new developments and/or impacted areas, which increase the amount of impervious surface. The maximum controlled stormwater runoff release rate shall not exceed the natural safe stormwater drainage capacity of the downstream system, which has been found to be 0.2 cubic feet per second, per acre in the count...
Erosion Control
Winnebago County requires a surface water management permit before any grading, clearing, excavating, or filling on unincorporated land covered by the ordinance.
Surface water management permit, Winnebago County
Significant RestrictionsWinnebago County Code of Ordinances § 50-254(e), § 50-255(a)
Required. A surface water management permit shall be required before beginning or continuing any land disturbing activity or development if such activity is subject to any of the provisions of this article. ... Except as otherwise provided in this article, no person shall commence or perform any land disturbing activity, including but not limited to clearing, grading, stripping, excavating, or ...
Flood Zones
Any construction, fill, grading or land subdivision in a Winnebago County flood hazard area needs written clearance from the county floodplain administrator before work starts. Code § 50-249 blocks the zoning officer, building official and plats officer from issuing any permit or plat approval in a known or suspected base flood area until the administrator signs off first.
Winnebago County Floodplain Development Permit Rule
Significant RestrictionsWinnebago County Code §§ 50-249(c), 50-248
After November 13, 1980, no zoning clearance, building permit, or plat or subdivision approval shall be issued by the zoning officer, building official or plats officer for a development activity or land subdivision in a known or suspected base flood area until the proposed use, structure, development, subdivision or activity is approved by the administrator. ... Base flood means the flood havi...
Flood Elevation Requirements
New and improved buildings in Winnebago County's floodplain must have their lowest usable space at least one foot above the base flood elevation.
Winnebago County 1-Foot Freeboard Rule
Some RestrictionsWinnebago County, IL Code of Ordinances Sec. 50-254(f)
Within the boundary of the regulatory floodplain, all usable space in new buildings, or added to existing buildings, shall either be elevated, floodproofed, or otherwise protected such that the lowest entry shall be at least one foot above the nearest base flood elevation to prevent the entry of surface stormwater. Floodproofing devices shall be operational without human intervention.
Environmental Rules by City in Winnebago County
1 cities in Winnebago County have their own environmental rules rules. Each link goes to that city's dedicated page with code citations.
All Winnebago County ordinances
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