Janesville WWTP - Municipal Wastewater Treatment in Town of Rock, Wisconsin

Janesville WWTP is a municipal wastewater treatment facility located in the Town of Rock, Rock County, Wisconsin. It serves a population of approximately 63,479, making it a medium-to-large agglomeration under US regulatory standards. The plant is situated in the Rock River basin, which ultimately drains into the Mississippi River system. Under the US Clean Water Act, plants of this scale are typically required to meet secondary treatment standards through National Pollutant Discharge Elimination System (NPDES) permits issued by the Wisconsin Department of Natural Resources. These permits set effluent limits for biochemical oxygen demand, total suspended solids, and other pollutants to protect water quality. The plant's treatment process and capacity are designed to handle the wastewater load from the community and comply with state and federal regulations. The treated effluent is discharged into the Rock River, a tributary of the Mississippi River. The Rock River supports diverse aquatic life and is used for recreation and drinking water downstream. The plant plays a key role in maintaining water quality in the watershed, preventing nutrient pollution and protecting downstream ecosystems in the Mississippi River basin.

The plant discharges into the Rock River, which flows southward through Wisconsin and Illinois before joining the Mississippi River near Rock Island, Illinois. The Rock River watershed supports a variety of fish species, including walleye and smallmouth bass, and provides habitat for migratory waterfowl. The plant's operations help control nutrient loading, particularly phosphorus and nitrogen, which can cause algal blooms in downstream waters including the Mississippi River and the Gulf of Mexico hypoxic zone.