Northfield STP Wastewater Treatment Plant, Green Oak Charter Township, Michigan

Northfield STP is a municipal wastewater treatment plant located in Green Oak Charter Township, Livingston County, Michigan. It serves a population of approximately 9,099 residents in this suburban community northwest of Ann Arbor. As a US facility serving fewer than 10,000 people, the plant is subject to EPA's NPDES permitting program under the Clean Water Act. For small to medium agglomerations, secondary treatment is typically required to meet effluent limits for BOD and TSS. The plant's discharge is regulated by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). The plant's treated effluent is discharged into local waterways that drain into the Huron River system, which flows into Lake Erie via the Detroit River. This watershed supports diverse aquatic life and provides drinking water for downstream communities. Proper treatment helps protect the Huron River's ecological health and recreational uses.

The plant discharges into tributaries of the Huron River, which flows southeast through Michigan to Lake Erie. The Huron River watershed supports a variety of fish species and is a popular area for fishing and paddling. Downstream, the river enters the Detroit River and ultimately Lake Erie, a Great Lake that provides drinking water to millions and sustains a major fishery. Protecting water quality in this basin is critical for both ecological integrity and human use.