Santa Rosa Wastewater Treatment Plant, Oaxaca, Mexico

Santa Rosa is a wastewater treatment plant located in the town of Santa Rosa, within the municipality of San Blas Atempa, Oaxaca, Mexico. The plant serves a population of 2,738 and operates with secondary treatment, discharging 259.20 m³/day of treated effluent. Its designed capacity is 362.88 m³/day. As a secondary treatment facility, Santa Rosa meets the standard requirements for municipal wastewater treatment in Mexico under NOM-001-SEMARNAT-1996, which sets maximum permissible limits for pollutants in wastewater discharged into national waters. The plant's scale corresponds to a small agglomeration, and its coastal location implies additional regulatory considerations for nutrient removal to protect marine ecosystems. The plant's treated effluent likely discharges into a local watercourse that flows into the Pacific Ocean, given its proximity to the coast. The region's coastal lagoons and estuaries support diverse aquatic life and are important for local fisheries. Proper treatment helps reduce nutrient loading and protects downstream marine habitats.

Santa Rosa is situated within 10 km of the Pacific coast in the Isthmus of Tehuantepec region. The treated effluent likely drains into a local stream or arroyo that flows into the Pacific Ocean, potentially affecting coastal lagoons and estuaries. These ecosystems support mangrove forests, fish nurseries, and migratory birds, making them sensitive to nutrient pollution and pathogen inputs. Secondary treatment reduces organic load and suspended solids, but additional nutrient removal may be needed to prevent eutrophication in the receiving coastal waters.