Erie Conservation District

Mills Creek

Mills Creek is a 42.4-square-mile watershed made up of many small tributary and drainage ditches. Mills Creek begins in Sandusky and Huron Counties encompassing the City of Bellevue and empties into Sandusky Bay on the west side of Sandusky. The watershed consists of approximately 26% developed land, 67% agricultural land, and 7% natural areas. There is one EPA permitted sewer outflow in the City of Bellevue that discharges into the headwaters of Mills Creek. This watershed is also home to several industrial areas with permitted discharges to the Creek.

Mills Creek is located on the easternmost portion of the Great Black Swamp, a once large wetland system created after Ancient Lake Erie’s shoreline receded to its present day location. The soil consists mainly of lake basin clay with a high seasonal water table. As a result, this area is commonly saturated in the spring months and drains slowly where drainage improvements have not been implemented. Mills Creek is also part of a Karst geological region, which is characterized by a series of sinkholes and underground rivers flowing through cracks and cavities in the limestone bedrock. Surface water and groundwater are more connected in Karst regions increasing the potential for flooding and groundwater pollution. Nearly the entire watershed is highly sensitive to groundwater contamination.

Key drivers

Mills Creek’s water quality is affected by many types of land uses, such as urban development, agricultural row-crop and livestock farms, commercial and industrial areas, and limestone quarries. The drainage of this watershed has been heavily modified including the use of tile, open ditch and sinkholes to carry excess stormwater from development and farm fields. This combined with Karst geology increases the transportability of pollutants through the watershed. Only 30% of the stream maintains a buffer of natural vegetation; reducing the stream’s ability to effectively handle the excessive flush of pollutants from rain events. This watershed also has the lowest adoption of conservation tillage in the county.

Municipal waste water from the City of Bellevue and several home sewage treatment systems also contribute to sediment, nutrient, and bacterial pollutants in the watershed.

2020 Mills Creek Watershed Report

Find out about the Ohio EPA Assessment of this watershed here.

Monitoring Sites at Mills Creek

Goodrich Road

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Miller Road East

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Miller Road West

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Mills Creek Golf Course

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Strecker Road East

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Strecker Road West

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Strub Road

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