Mill Creek in southwest Ohio is one of the most severely polluted and physically degraded streams in the United States. In 1997, because of its multiple stressors and sources of pollution, the national river conservation group American Rivers designated Mill Creek as "the most endangered urban river in North America."
The stream flows 28 miles south from its headwaters in Butler County through the geographic heart of Hamilton County and the City of Cincinnati to its confluence with the Ohio River, just west of the downtown riverfront. Its watershed covers southeast Butler County and approximately the central third of Hamilton County and encompasses all or parts of 37 political jurisdictions. Within the City of Cincinnati, over forty neighborhoods are located in the Mill Creek drainage basin.
Half a million people live in this industrial and urban watershed, and another half million or more work in and travel through the watershed on a daily basis. Historically, the creek served as an extremely valuable and significant resource, supporting the economic growth and development of the Greater Cincinnati region. Internationally recognized companies like Procter & Gamble, General Electric Aircraft Engines and the Ford Motor Company still operate facilities along the banks of Mill Creek.
Unfortunately, over the past 100 years, as the quality of the watershed’s environment progressively deteriorated from the cumulative impacts of intense urbanization, channelization and industrial use, the economic health of the area also dramatically declined. Today, thousands of people of color and Appalachian descent live in economically-depressed neighborhoods and communities along and near the creek. These watershed residents bear a disproportionate share of the problems resulting from a degraded environment and associated health risks and diminished quality of life. According to the 2000 census, in some floodplain neighborhoods the unemployment rate is as high as 37.5 percent and the poverty rate and percent of minority population has significantly increased over the previous ten years.
In 1992, Ohio EPA conducted its first comprehensive chemical and biological survey of Mill Creek and some of its tributaries. On the Mill Creek mainstem, levels of bacteria and viruses from raw sewage exceeded acceptable federal and state water pollution standards at virtually every sampling site. There were elevated levels of lead and other heavy metals, organic compounds, pesticides and ammonia. Sediment samples taken at a number of sites indicated elevated levels of a variety of metals including lead, zinc, copper, cadmium, and chromium. Fish and benthic macroinvertebrates were adversely impacted by multiple stressors, including contaminated sediments, channelization of the stream, loss of stream and riparian habitat, combined sewer overflows and other pollutants, and a widely-ranging flow regime.
Ohio EPA found only pollution-tolerant fish and other aquatic species like sludge worms, blood worms, and leeches in inner-city segments of the creek. Polychlorinated biphenyls (PCBs) were found in fish tissue, resulting in a fish consumption advisory by the Ohio Department of Health. For almost all of the Mill Creek main channel in Hamilton County, and for a number of tributaries, the Ohio EPA recommended that there be no public contact with the stream. Despite the regulatory warnings and the public perception of the creek’s mainstem as an open sewer, many people, especially children from affected communities, continue to fish and wade in the creek, because kids love water and Mill Creek is their "backyard" stream.
If you are interested in more Mill Creek history you may want to read The Mill Creek: An Unnatural History of and Urban Stream by Dr. Stanley Hedeen.