Colusa WWTP - Municipal Wastewater Treatment in Colusa County, California

Colusa WWTP is a municipal wastewater treatment facility located on Harbison Road in Colusa County, California. It serves a population of about 5,670 residents, classifying it as a small to medium-sized plant within the state's wastewater infrastructure. The facility is situated inland, more than 50 kilometers from the Pacific coast, and operates under the regulatory oversight of the US Environmental Protection Agency and the California State Water Resources Control Board. As a plant serving fewer than 10,000 people, Colusa WWTP is subject to the US Clean Water Act's National Pollutant Discharge Elimination System (NPDES) permitting program. Facilities of this scale typically employ secondary treatment or advanced technologies to meet state and federal effluent standards. The plant's design capacity and operational status are consistent with standard practices for small agglomerations in California. The treated effluent from Colusa WWTP is discharged into local waterways that drain into the Sacramento River system, ultimately reaching the Sacramento-San Joaquin Delta and San Francisco Bay. This watershed supports diverse aquatic habitats and is critical for regional water supply and ecosystem health. The plant's operations contribute to protecting water quality in this sensitive downstream environment.

Colusa WWTP discharges into tributaries of the Sacramento River, which flows into the Sacramento-San Joaquin Delta and then San Francisco Bay. This watershed supports important fish species, including salmon and steelhead, and provides habitat for migratory birds. The plant's effluent management is crucial for maintaining water quality in this ecologically significant river system.