CASTALIA STL Wastewater Treatment Plant, Winneshiek County, Iowa

CASTALIA STL is a municipal wastewater treatment facility located in Bloomfield Township, Winneshiek County, Iowa. Serving a small population of 175, the plant provides secondary treatment to meet state and federal water quality standards under the U.S. Clean Water Act. The plant has a designed capacity of 71.92 and discharges an average volume of 174.13, indicating it operates within its capacity. As a secondary treatment facility, it uses biological processes to reduce organic matter and suspended solids before discharge. Treated effluent from the plant flows into local streams that drain into the Upper Mississippi River Basin. This region supports diverse aquatic life and is an important corridor for migratory birds. The plant's operations help protect downstream water quality in the Mississippi River system.

The plant discharges into small tributaries of the Upper Mississippi River, which ultimately flows into the Gulf of Mexico. The local watershed is primarily agricultural, and the plant helps reduce nutrient loading that could contribute to hypoxia in the Gulf. The receiving waters support fish, macroinvertebrates, and provide habitat for waterfowl.