Winnebago County, IL Environmental Rules: Flood Zones (2026)

Article IV of Chapter 50, the Surface Water Management Ordinance, regulates flooding in the unincorporated county through its floodplain provisions at §§ 50-247 through 50-254. Section 50-247(a)(1) folds in the Illinois Sample Flood Damage Prevention Ordinance's technical sections 6 through 10 to keep the county in the National Flood Insurance Program, and § 50-248 defines the 'floodplain' as land subject to inundation by the base flood, the flood with a one percent annual chance of occurring, as mapped on FEMA panels 17201C0020D through 17201C0415D.

Section 50-249 puts the county engineer in charge as administrator: no zoning clearance, building permit, or plat/subdivision approval can issue for a base flood area until the administrator approves the plan, and after November 13, 1980, well permits and onsite waste systems in the county must also go through the administrator's office. Reviews take up to 30 days and can be approved, conditioned, or disapproved in writing with reasons.

Section 50-254(b) lists the activities that trigger this clearance: new construction, substantial improvement of an existing structure, any work on a structure inside the floodway, placing a mobile home, storing chemicals or debris, building or expanding a mobile home park, land-disturbing landscape work, watercourse modification, and any subdivision or land transfer regardless of size.

Violating the article is a petty offense under § 50-250(n), fined $25 to $500 per day, and the administrator can also record a notice of violation against the property's title and warn the owner that flood insurance coverage may be suspended for a willful violation. A hardship variance can be requested from the county board under § 50-259, but only after showing the project can't be relocated outside the floodplain and that granting it adds no public safety or expense risk.