Date Approved


Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School


Committee Member

Kristin Judd, Biology

Committee Member

Steven Francoeur, Biology

Committee Member

Daniel Clemans, Biology


Plastic pollution is a global issue affecting the health and stability of freshwater and marine environments. Microplastics can be introduced into waterways from a variety of sources, such as agricultural runoff, anthropogenic litter, and wastewater treatment plants (WWTPs). To determine whether WWTPs are a source of microplastics to the Lower Rouge and Huron Rivers, we measured microplastic load upstream and downstream of two Southeast Michigan wastewater treatment plants: the Ann Arbor Wastewater Treatment Plant and Ypsilanti Community Utilities Authority (YCUA). Results from this study indicated that YCUA, which discharges into a small stream with limited watershed inputs, is a significant source of microplastic pollution. The Ann Arbor WWTP, which discharges into the much larger Huron River, was not a detectable source. Instead, the positive relationship between river discharge and microplastic load suggests that watershed sources may be more important to total microplastic load, especially in larger rivers.