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.

Mill Creek Timeline

1800s: The Mill Creek Valley is settled. Settlers bring industry. Decline of the creek
begins.

Jan. 24, 1937: The Mill Creek turns into a raging river during the Flood of 1937. Gasoline
spills from toppled tanks and catches fire. The burning creek claims many homes and
businesses.

1959: Floods cause millions of damage to businesses along the Mill Creek.

1962: Mill Creek Conservancy District is formed to act as the local liaison for Army Corps
of Engineers' flood-control projects.

1981: After much planning, the Corps of Engineers begins work on Mill Creek flood
control project that calls for channelizing roughly 17 miles of the creek.

1991: Corps of Engineers abandons the project because of spiraling costs and lack of
money.

1992: Ohio EPA study finds pollution and recommends no public contact with the stream.

1993: Hamilton County Environmental Commission declares Mill Creek the worst
environmental problem in Greater Cincinnati

1994: Mill Creek Restoration Project, an advocacy group, forms.

1996: Mill Creek communities form a watershed council - a multi-jurisdictional approach
to watershed management. This group crafts a master watershed plan for Upper Mill
Creek in Butler County.

1997: The creek is designated the "most endangered urban river in North America" by
the conservation group American Rivers.

1998: Mill Creek floods again. People rescued from the tops of their cars.

Aug. 1998: The Army Corps launches a $2.5 million study to figure out how to complete
its abandoned flood-control project.

April 2000: Workers on the Upper Mill Creek Wastewater Treatment facility in Butler
County uncover a woolly mammoth leg bone and tooth.

July 17, 2001: Floods again rip through region, killing three and causing millions in
damage. GE plant has $40 million in damage to equipment and inventory.

January-July 2001: Homes are torn down along the West Fork of the Mill Creek flood
plain in Colerain Township. The Federal Emergency Management Agency provides
money to buy the houses.

August 2001: Corps of Engineers considers a "deep tunnel," a 16-mile long, 30-feet
diameter tunnel underneath the river to contain floodwater. The project is too expensive
and is rejected.

2005: Corps of Engineers recommends a $606 million creek-widening project stretching
from Sharonville to Arlington Heights to protect 1,900 homes and businesses from
floodwaters of the Lower Mill Creek. The project calls for more channelizing. The project
would be completed by 2014 but never gets off the ground because the local
communities can't come up with their share.

July 14, 2005: West Chester Township gets Clean Ohio grant for $618,000 to buy and
preserve 300 acres along the Upper Mill Creek Conservation Corridor. The corridor runs
from Gilmore Ponds in Hamilton to behind the Rave Motion Pictures at the Streets of
West Chester.

April 19, 2006: Cincinnati City Council passes a resolution to acquire permanent
conservation easements on property owned by the Mill Creek Valley Conservancy
district. This act is taken on Earth Day and reaffirms the city's commitment to its Mill
Creek Greenway Program.
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