Castorland V WWTP - Secondary Treatment Plant in Town of Denmark, New York

Castorland V WWTP is a municipal wastewater treatment facility located in the Town of Denmark, Lewis County, New York. The plant serves a small population of 306 residents, reflecting its role in a rural community within the Black River Valley region. The facility provides secondary treatment, which is the standard level required under the U.S. Clean Water Act for municipal plants. With a designed capacity of 143.85 megaliters per year and an actual discharge volume of 94.64 megaliters per year, the plant operates below its capacity, indicating room for future growth or seasonal variability. The treated effluent is discharged into a local waterway that ultimately drains into the Black River, a tributary of Lake Ontario. This places the plant within the Great Lakes Basin, where nutrient management is critical to prevent algal blooms and protect aquatic ecosystems. The plant's secondary treatment helps reduce organic pollutants and suspended solids before discharge.

The plant's discharge enters a tributary of the Black River, which flows into Lake Ontario, part of the Great Lakes system. The Black River watershed supports diverse aquatic life, including coldwater fisheries, and is an important migratory corridor for fish. Nutrient loading from wastewater can contribute to eutrophication in Lake Ontario, making effective treatment essential for downstream water quality.