Mill Creek Watershed (Ohio River Basin)

Mill Creek watershed (Ohio River basin)The Mill Creek watershed is located in southwestern Ohio. Mill Creek flows into the Ohio River in Cincinnati. It drains a total of 169 square miles and flows through all or part of three counties. Major municipalities partially or fully in the watershed include Cincinnati and some of its suburbs, Fairfield, Hamilton and Beckett Ridge.

The watershed is predominantly comprised of urban development with pockets of forest and a small amount of agricultural lands in the northern portion of the watershed. Industry dominates the mid- to lower reaches of the watershed, and commercial and suburban uses are predominant in the upper watershed. The watershed also contains several CSOs and SSOs. Old industrial landfills line the banks of Mill Creek in some areas and several old hazardous waste sites have the potential to influence the stream.

Most of the mainstem and major tributaries have been assigned the Warmwater Habitat aquatic life use designation. Permanent channel modification by U.S. Army Corps of Engineers resulted in assigning Modified Warmwater Habitat to the lower eight miles of Mill Creek. U.S. ACOE, local jurisdictions, and property owners have also done additional stream alterations in much of the watershed. U.S. ACOE is presently reevaluating the flood reduction strategy for Mill Creek.

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This watershed was studied in 2014.

TMDL Report

The Mill Creek Watershed Total Maximum Daily Load report (TMDL) was approved by U.S. EPA on April 26, 2005. TMDLs identify and evaluate water quality problems in impaired water bodies and propose solutions to bring those waters into attainment.

Although many causes of impairment have been identified (nutrient and organic enrichment, heavy metals, pesticides, priority organic chemicals, contaminated sediments, siltation, low dissolved oxygen, habitat and flow alterations, and pathogens), the TMDL addresses only nutrients (phosphorus and nitrogen). Additional TMDL work (or some other path to attainment of water quality standards) will be needed to remove Mill Creek from the 303(d) list.

Final Report without appendices (September 2004)

Supplemental Information