Cook County Drainage Analysis & Water Flow Map

Address
Overview

Where does rainwater drain in Cook County? This interactive map shows surface drainage patterns across Chicago, Evanston, Oak Park, and surrounding areas based on terrain shape - where gravity directs rainwater based on elevation and slope. For official flood risk information, see the FEMA flood zone layer on the Hazards tab.

Cook County's flat glacial terrain and heavy clay soils create persistent drainage challenges across the Chicago metro. The Chicago River was famously reversed to flow away from Lake Michigan, but the engineered drainage system still overwhelms during heavy rain. The TARP deep tunnel project captures combined sewer overflow, but basement flooding remains widespread in older neighborhoods with clay-heavy soils. Enter any address to see parcel-level surface drainage analysis and water flow direction based on terrain shape.

Interpretation

Select a location on the map or enter an address to see terrain analysis.

3D Terrain Visualization
Where does rainwater flow based on terrain shape? Blue areas show where water collects and drains downhill.
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