AT ONE TIME, THE MILL CREEK WAS THE MOST POLLUTED AND PHYSICALLY DEGRADED STREAM IN THE UNITED STATES.

In 1997, because of its multiple stressors and sources of pollution, the national river conservation group American Rivers designated Mill the “most endangered urban river in North America.”

Unfortunately, over the past 100 years, as the quality of the watershed's environment 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 quality of life problems resulting from a degraded environment and associated health risks. 

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, 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 main stem 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.