SAN MIGUEL STP - Secondary Wastewater Treatment Plant in San Miguel, California

SAN MIGUEL STP is a municipal wastewater treatment facility located in San Miguel, California, United States. The plant serves a population of approximately 1,400 residents in this small inland community within San Luis Obispo County. 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 757.08 m³/day and an actual discharge volume of 378.54 m³/day, the plant operates at roughly half its capacity, indicating room for future growth. As a US facility, it operates under a National Pollutant Discharge Elimination System (NPDES) permit issued by the California State Water Resources Control Board, ensuring compliance with federal and state water quality standards. The treated effluent is discharged into a local watercourse that ultimately drains into the Salinas River basin and then to Monterey Bay National Marine Sanctuary in the Pacific Ocean. The plant plays a critical role in protecting downstream aquatic ecosystems and groundwater quality in California's Central Coast region.

The plant discharges into a tributary of the Salinas River, which flows through the Salinas Valley and empties into Monterey Bay, part of the California Current Large Marine Ecosystem. This watershed supports diverse aquatic life, including steelhead trout and other sensitive species. The plant's secondary treatment helps reduce nutrient loading and protect downstream water quality in this agriculturally important region.