This inventory involves identifying and mapping storm water “outfalls” – every point where a conveyance of ODOT’s storm water system discharges into streams, lakes, and wetlands. More than 6,800 outfalls have been identified for over 1,900 miles of roadways and more than 90 ODOT facilities (rest areas, garages, offices) in the MS4 regulated (urbanized) areas.
ODOT’s MS4 Stormwater Outfall Inventory Manual describes the process for conducting the inventory and contains relevant mapping. Specific attributes (receiving stream, pipe shape, etc.) were collected for each outfall. It was noted whether flow is present in dry weather, which may point to a pollution source upstream.