Richvale WWTF - Colusa County, California Wastewater Treatment Plant

Richvale Wastewater Treatment Facility (WWTF) is located in Colusa County, California, within the Sacramento Valley. The plant serves a small community of approximately 300 residents, reflecting its role in rural wastewater management. The facility provides secondary treatment, a standard level for small communities under the U.S. Clean Water Act. With a design capacity of 151.42 megaliters per year and an annual discharge volume of 113.56 megaliters, the plant operates well within its capacity. As a publicly owned treatment works, it is subject to National Pollutant Discharge Elimination System (NPDES) permitting, which regulates effluent quality to protect receiving waters. The plant discharges to Willow Creek, a tributary of the Sacramento River system. The Sacramento River flows through the Central Valley to the Sacramento-San Joaquin Delta and ultimately into San Francisco Bay. This watershed supports diverse aquatic life and is critical for regional water supply and agriculture.

Richvale WWTF discharges into Willow Creek, which flows into the Sacramento River system. The Sacramento River drains the Central Valley and empties into the Sacramento-San Joaquin Delta, a vital estuarine habitat that supports fish species such as salmon and delta smelt. The plant's secondary treatment helps protect downstream water quality in this ecologically sensitive watershed.