National model of restoration: Nine Mile Run

Pittsburgh's Frick Park is home to Nine Mile Run, a stream that had been known as "Stink Creek." From 2003 to 2006, the City of Pittsburgh and the U.S. Army Corps of Engineers poured $7.7 million into restoring 2.2 miles of the stream and tributaries into waterways approximating what they were prior to urban development.

The project remains one of the largest urban-stream restorations undertaken in the United States.

What can this restoration teach us as we continue to deal with streams affected by urbanization?

The University of Pittsburgh's Dan Bain, assistant professor of hydrology and metal biogeochemistry in the Department of Geology and Planetary Science within the Kenneth P. Dietrich School of Arts and Sciences, says the project has made a difference and sets an example for other cities to follow. The evidence is tallied in Bain's paper, "Characterizing a Major Urban Stream Restoration Project: Nine Mile Run," published this month in the Journal of the American Water Resources Association.

Nine Mile Run, which is part of a watershed that drains 6.5 square miles of Wilkinsburg, Edgewood, Swissvale, Forest Hills, Squirrel Hill, and Point Breeze, had been truly abused by urbanization and industrialization. Toxins leached into the creek from a slag heap left over from the steelmaking process, sewer lines discharged into the water, and so much of the waterway had been buried in culverts or diverted from its natural path that Nine Mile Run had become toxic.

The three-year restoration project involved rerouting the creek to a natural pathway, reestablishing flora, creating areas to catch floodwater, and building natural "slash piles" and "snags" from cut-down trees to create bird and animal habitats. It also involved infrastructure interventions: adding rain barrels to individual's homes, preventing some storm water from overwhelming the stream, and fixing parts of the underlying sewers.

Some of the impediments remain, but neighbors and Frick Park users have been motivated to continue the work. Those inspired by the improving health of the stream have enlisted as volunteer Urban EcoStewards with the Nine Mile Run Watershed Association, a nonprofit that advocates for and monitors the area. These EcoStewards visit an assigned plot on a regular basis to remove invasive species, plant native flora, clean up trash, and install rain barrels on their property to reduce runoff and slow erosion.

In his paper, Bain reports that fish populations are improving as are populations of macroinvertebrates--insects, crustaceans, etc.--that fish feed on, though their recovery is coming along more slowly. However, the human response to this restoration has been vigorous--the rise in the number of volunteer hours as well as the number of rain barrels installed at private residences appears to be associated with the restoration of the stream. If replicated elsewhere, community involvement should be considered an important part of sustaining improvements in stream health.

"What we found is that, properly done, urban-stream restoration can create a citizen involvement in the process of appropriately managing urban streams and give us a greater opportunity to understand how restorations work in an urban system, particularly when compared with our ability to understand restoration success in less populated areas," Bain says.