Yosemite West WWTF - Secondary Wastewater Treatment in Mormon Bar, California

Yosemite West WWTF is a wastewater treatment facility located in Mormon Bar, California, within Mariposa County. The plant serves a small population of 350 residents and operates under secondary treatment standards, which is typical for facilities of this scale in the United States. The plant has a designed capacity of 378.54 megaliters and reports an annual discharge volume of 113.56 megaliters. As a US facility, it operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the California State Water Resources Control Board, ensuring compliance with federal water quality standards. The treated effluent is discharged into the local watershed, which ultimately drains into the Merced River and then the San Joaquin River system, flowing into the Sacramento-San Joaquin Delta and San Francisco Bay. This region supports diverse aquatic habitats and is important for migratory fish species.

The plant's discharge enters the Merced River watershed, a tributary of the San Joaquin River that flows through the Sierra Nevada foothills. The downstream environment includes the San Joaquin River and the Sacramento-San Joaquin Delta, which is a critical estuarine ecosystem supporting fish, birds, and other wildlife. The area is ecologically sensitive due to its role in providing habitat for threatened species and maintaining water quality for agricultural and urban uses.