Stormwater Management: Des Plaines vs Evanston

Do I need stormwater approval for a home addition?

Small residential additions are typically below WMO thresholds, but lot grading must still drain away from the foundation and not concentrate flows onto neighbors. Larger projects may trigger detention requirements.

Who regulates stormwater in Des Plaines?

The MWRD Watershed Management Ordinance is the controlling regulation, administered locally by Des Plaines's Department of Public Works/Engineering at (847) 391-5390.

Why does Des Plaines flood so often?

Des Plaines is located along the Des Plaines River and Higgins Creek with significant low-lying areas. The City participates in the NFIP and has invested in flood mitigation, but flooding remains a regional challenge.

When is a stormwater management plan required in Evanston?

Projects disturbing 5,000 square feet or more or increasing impervious surface by more than 2,500 square feet must provide a stormwater management plan prepared by a licensed engineer. The plan must comply with MWRD Watershed Management Ordinance standards.

Can I use rain gardens instead of detention basins?

Yes. Evanston encourages green infrastructure including rain gardens, bioswales, permeable pavers, and green roofs. These may satisfy part of the detention requirement. Contact Public Works for design criteria.

Does Evanston have combined sewer issues?

Yes. Portions of Evanston have combined sewer systems. The city encourages downspout disconnection and green infrastructure to reduce stormwater inflow to combined sewers and minimize basement flooding during heavy rain events.