Kane County, IL Environmental Rules: Stormwater Management (2026)

Kane County Code section 9-28(A), part of the Stormwater Management Ordinance adopted by Ordinance 19-151, requires a permit whenever a development sits in the regulatory floodplain, involves a substantial improvement in the floodplain, impacts a wetland, or disturbs more than five thousand square feet of ground or two hundred fifty cubic yards of earth, soil, clay or gravel. Table 9-81 then scales the measures required to the amount of new impervious area created: any project adding twenty-five thousand square feet or more of impervious surface must build a detention storage facility under section 9-84, sites between five thousand and twenty-four thousand nine hundred ninety-nine square feet trigger a stormwater mitigation or best-management-practice requirement under section 9-107, and projects disturbing more than three acres, or adding impervious cover to over half a site under an acre, face detention and BMP requirements together.

The Administrator may waive a detention facility and approve a fee-in-lieu payment instead under section 9-81(B)(4) if the project will not raise peak discharge and provides a net water-quality benefit. Permits run through the county's stormwater program, require plans sealed by a professional engineer, and expire on December 31 of the third year after issuance under section 9-29; construction on a new floodplain structure must start within one hundred eighty days of issuance or the applicant must resubmit for a current base flood elevation. A denied or conditioned permit can be appealed to the oversight committee within ten days under section 9-36.