URBAN STREAM RESTORATION AND WATER QUALITY: THE CASE OF NINE MILE RUN (PITTSBURGH, PA)

Advocates of urban stream restoration often emphasize the multiple bottom line benefits of restoration projects. For example, projects restoring physical habitat might improve green space and water quality in addition to habitat outcomes. Yet, due to the economics of environmental restoration, complete accounting of these benefits are not common. Nine Mile Run, a stream draining Pittsburgh's East End, underwent a multi-million dollar restoration in 2006, including efforts to “reconnect” the floodplain, a concept that is garnering increasing attention for potential nutrient management benefits. By combining characterization of the system from periods of project planning and more recent water sampling, we are able to evaluate the impacts of the restoration on some aspects of water quality. For example, nitrate concentrations in the stream following restoration do not necessarily drop, despite observed changes in nitrate concentrations reported in other projects employing floodplain restoration. This likely results from the complicated infrastructure common to urban systems. Ultimately, improvements in urban water quality via in-channel projects will require extended adaptive management, particularly careful evaluation of results, to succeed.