Joliet, IL Environmental Rules: Stormwater Management (2026)

Chapter 31, Article V, Division 4 of the Joliet City Code sets the city's stormwater detention standards. Section 31-204 lays out the numeric triggers still on the books: a detention facility and controlled release are required for any new nonresidential development over 5 acres, any new residential development over 10 acres, and any new construction or parking-area improvement that pushes impervious cover to 60 percent or more, measured against the entire parcel where the improvement touches land developed before October 2, 1973. S. 30 runoff coefficient.

The Director of Public Works reviews and approves detention methods, discharge-restriction methods, and supporting calculations, and can waive detention for a new storm sewer extension if an adequate outfall or downstream retention facility already exists or is planned. Under subsection (h), a building permit will not issue until the applicant proves to the Director's satisfaction that construction will meet these terms. Section 31-204 itself only governs developments whose preliminary plat was filed or approved before December 1, 1993. For everything built since, Section 31-205 adopts the stormwater detention regulations effective that date, and Sections 31-206 and 31-207 adopt the city's site development permit and design and operation standards, all by reference to Ordinance No.

10323; none of that later text is reproduced in the code itself, it is kept on file and available for inspection in the office of the city clerk. If the detention facility later falls into disrepair and threatens public health, safety, or welfare, subsection (e) lets the city pursue any court proceeding needed to recover the cost of restoring it, at the owner's expense, since maintenance is the owner's obligation, not the city's.