Nine Mile Run is a small stream that flows through Pittsburgh’s East End. If you’ve ever driven through Wilkinsburg, Edgewood, Swissvale, or the east side of Squirrel Hill, you’ve driven over it. Of course, you don’t need to cross a bridge to drive over Nine Mile Run because it is almost entirely underground.
Currently, Nine Mile Run is unhealthy, typical for an urban stream, and a result of how little the stream has been valued historically. At the turn of the 20th century streams were often used to transport trash and sewage from homes, and most of Nine Mile Run was piped into underground culverts.
One-third of the stream was left above ground in Frick Park, emerging near Braddock Avenue and flowing 2.2 miles to the Monongahela River. This unique urban asset is located in a 6.5 square mile watershed that includes the boroughs of Edgewood, Swissvale, Wilkinsburg and part of the city of Pittsburgh.
The Nine Mile Run Aquatic Ecosystem Restoration was completed by the Army Corps of Engineers in July 2006. It was the largest urban stream restoration in the United States at the time of its completion, and the work involved included stream channel reconfiguration, wetland reconstruction, native wildlife habitat enhancement, and native tree, shrub, and wildflower plantings. This work was done on the open portion of the stream flowing freely through Frick Park. Please click here for more information.
Problems still affecting Nine Mile Run
The restoration made Nine Mile Run a much more beautiful place to visit, and has improved many aspects of the ecological health of the stream. However, Nine Mile Run still faces many challenges due to its urban location.
Nearly one-third of the Nine Mile Run watershed is covered by impervious surfaces, which allow stormwater runoff to flow directly into storm drains instead of being absorbed into the ground. Since the entire upper portion of Nine Mile Run flows through the storm sewer system, that means during wet weather, the stream is quickly overloaded with runoff, flooding it with pollutants (e.g., litter, road salt, oil, pesticides, etc.) and causing stream bank erosion.
Unfortunately, non-point source pollution from stormwater runoff is not the only pollutant affecting the stream. Sewage overflows occur regularly during wet weather because of aging and inadequate storm and sanitary sewer systems. Sewage contains pathogens that make the stream unsafe for human recreation most of the time, despite its improved appearance.
How does sewage get into Nine Mile Run?
Most of the City of Pittsburgh uses a combined system in which both sewage and stormwater flow through the same pipes, which means sewage can spill into Nine Mile Run when there is as little as a tenth of an inch of rain.
Wilkinsburg, Edgewood and Swissvale have a two-pipe system called a sanitary sewer system; one pipe to carry sewage and one to carry stormwater. However, many watershed citizens have (often unbeknownst to them) their downspouts connected to the sewer drains instead of the stormwater drains. Many of the sewer pipes are also aging, cracked, and in disrepair, meaning sewage leaks occur quite often.
For more information on these sewer overflow problems that affect Nine Mile Run & the entire Pittsburgh region, please visit the Clean Rivers Campaign website.