Oso Creek Water Reclamation and Recycling Facility (WWRF) - Mission Viejo, California

Oso Creek Water Reclamation and Recycling Facility (WWRF) is a municipal wastewater treatment plant located in Mission Viejo, Orange County, California. The plant serves a population of approximately 31,398 residents in this suburban community within the Los Angeles metropolitan area. As a US facility, Oso Creek WWRF 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. For a plant serving over 30,000 people, secondary treatment is the minimum standard, though many California plants employ advanced treatment for water reuse given the state's water scarcity. The plant's treated effluent is discharged into Oso Creek, a tributary of San Juan Creek, which flows into the Pacific Ocean at Dana Point. The receiving waters support aquatic life and are part of the larger San Juan Creek watershed, which drains the Santa Ana Mountains. The plant's proximity to the coast (within 50 km) means its discharge can affect coastal water quality and marine ecosystems.

Oso Creek WWRF discharges into Oso Creek, which flows into San Juan Creek and ultimately reaches the Pacific Ocean at Dana Point Harbor. The watershed drains the western slopes of the Santa Ana Mountains and supports riparian habitats. The coastal discharge zone is part of the Southern California Bight, a region with sensitive marine ecosystems including kelp forests and rocky reefs. Effluent quality is critical to protect recreational beaches and marine life in this densely populated coastal area.