Shell Rock WWTP - Secondary Treatment Plant in Butler County, Iowa

Shell Rock WWTP is a municipal wastewater treatment facility located in Butler County, Iowa, United States. The plant serves a population of approximately 1,298 residents, classifying it as a small-scale treatment facility within the state's wastewater infrastructure. The plant provides secondary treatment, which is the standard level required by the US Clean Water Act for municipal wastewater facilities. With a designed capacity of 1,059.91 thousand cubic meters per year and an actual discharge volume of 567.81 thousand cubic meters per year, the plant operates well within its capacity. As a US facility, it operates under the National Pollutant Discharge Elimination System (NPDES) permit program, administered by the Iowa Department of Natural Resources, ensuring compliance with effluent limits. The treated effluent is discharged into local streams that are part of the Cedar River watershed, which ultimately flows into the Mississippi River. This watershed supports diverse aquatic life and provides water for agricultural and recreational uses downstream. The plant's secondary treatment helps protect water quality in this important river system.

The plant discharges into tributaries of the Cedar River, which flows into the Mississippi River, a major waterway draining much of the central United States. The Cedar River watershed supports diverse fish populations and provides habitat for migratory birds. Secondary treatment reduces organic pollutants and suspended solids, helping maintain water quality for downstream communities and ecosystems.