Tinley Park, IL Environmental Rules: Stormwater Management (2026)

Tinley Park falls under the MWRD Watershed Management Ordinance (effective May 1, 2014, with subsequent updates), which governs stormwater management throughout Cook County. The WMO requires stormwater detention for development creating 0.5 acres of hydrologically-disturbed area or meeting other trigger thresholds, with detention release rates limited to 0.15 cfs per acre for 100-year events. Volume control standards require capture and retention of the first 1 inch of runoff from new impervious surface. Floodplain and wetland impacts trigger additional permitting. Tinley Park as the local municipality reviews WMO compliance for most projects and issues a Village stormwater permit tied to WMO approval. Projects in regulatory floodplain along Tinley Creek and tributaries require additional floodplain development permits and compliance with FEMA flood insurance rate map base flood elevations. The Village's MS4 (Municipal Separate Storm Sewer System) National Pollutant Discharge Elimination System permit prohibits illicit discharges of anything other than stormwater into the storm sewer system. Residents should not wash cars into storm drains, dump motor oil or paint into drains, or let grass clippings enter drainage swales.