Las Marias WWTP - Secondary Treatment Plant in Las Marias, Puerto Rico

Las Marias WWTP is a municipal wastewater treatment facility located in Las Marias, Puerto Rico, serving a population of approximately 1,400 residents. The plant provides secondary treatment, which is the standard level required under the US Clean Water Act for most municipal facilities to reduce organic matter and suspended solids before discharge. The plant has a designed capacity of 946.35 thousand cubic meters per year and currently treats an annual discharge volume of 567.81 thousand cubic meters. As a facility in a US territory, it operates under the regulatory framework of the US Environmental Protection Agency (EPA) and the Puerto Rico Environmental Quality Board, which enforce National Pollutant Discharge Elimination System (NPDES) permits to ensure compliance with water quality standards. The treated effluent from Las Marias WWTP is discharged into local waterways that ultimately drain to the Caribbean Sea. The surrounding watershed supports diverse aquatic life and contributes to the ecological health of coastal ecosystems in western Puerto Rico. Proper treatment helps protect downstream water quality and marine habitats.

The plant discharges into local streams that flow toward the Caribbean Sea, a major marine ecosystem supporting coral reefs, seagrass beds, and diverse fish populations. The watershed in western Puerto Rico is characterized by tropical climate and mountainous terrain, making water quality management critical for both human use and ecological integrity. Secondary treatment reduces pollutants that could otherwise contribute to eutrophication or harm sensitive coastal habitats.