S MARIN SUBREG OUTFALL, Mill Valley

Overview

S MARIN SUBREG OUTFALL is a wastewater treatment plant in Mill Valley, California, serving approximately 28,000 people. It is located within 50 km of the coast and discharges into the San Francisco Bay watershed.

S MARIN SUBREG OUTFALL is a wastewater treatment plant serving the Mill Valley area in Marin County, California. The facility handles wastewater for a population of about 28,000, operating as part of the regional wastewater infrastructure in the San Francisco Bay Area. As a subregional outfall, it plays a key role in managing effluent from multiple communities. The plant's designed capacity is 1.00 million gallons per day, reflecting its scale as a medium-sized facility. Under the U.S. Clean Water Act, such plants are required to meet National Pollutant Discharge Elimination System (NPDES) permit standards, which typically mandate secondary treatment and may include additional nutrient removal to protect sensitive waters. The California State Water Resources Control Board oversees compliance with these regulations. The treated effluent from this plant is discharged into the San Francisco Bay, a major estuary that supports diverse aquatic life and serves as a critical habitat for migratory birds and fish species. The bay ultimately connects to the Pacific Ocean through the Golden Gate. Protecting water quality in this watershed is essential for maintaining the ecological health of the bay and its downstream marine environment.

Environmental context

The plant discharges into the San Francisco Bay watershed, which drains into the Pacific Ocean. The bay is a highly productive estuary that supports endangered species such as the Delta smelt and Chinook salmon. Nutrient loading from wastewater can contribute to algal blooms and hypoxia, making advanced treatment important for preserving water quality in this ecologically sensitive region.

Frequently asked questions

S MARIN SUBREG OUTFALL is located in Mill Valley, Marin County, California, United States. The plant serves the Mill Valley area and surrounding communities.

The plant discharges treated wastewater into the San Francisco Bay, which is a major estuary that flows into the Pacific Ocean. The discharge is regulated under the Clean Water Act to protect water quality.

The plant helps protect the San Francisco Bay watershed, which includes tributaries such as the Sacramento and San Joaquin rivers. By treating wastewater, it reduces pollutant loads that could affect these waterways and the bay ecosystem.

The plant operates under the Clean Water Act, which requires NPDES permits for all wastewater discharges. These permits set limits on pollutants to ensure the receiving water body meets water quality standards. California's State Water Resources Control Board enforces these permits.

For a population of 28,000, typical treatment includes secondary treatment (biological process) to remove organic matter and solids. Many plants also incorporate disinfection and, in sensitive areas like San Francisco Bay, may include nutrient removal to reduce nitrogen and phosphorus.