Phoenix 91st Ave WWTP - Major Wastewater Treatment Plant in Phoenix, Arizona

The Phoenix 91st Ave WWTP is a major wastewater treatment facility located in Phoenix, Arizona, serving a population of approximately 1.76 million residents. As one of the largest treatment plants in the southwestern United States, it plays a critical role in managing the region's water resources within the arid Sonoran Desert climate. As a large agglomeration serving over 150,000 people, the plant operates under the U. S. Clean Water Act, which requires secondary treatment as a minimum standard. The facility is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Arizona Department of Environmental Quality, ensuring compliance with federal and state water quality standards. The treated effluent is discharged into the Salt River, a tributary of the Gila River, which flows into the Colorado River. This water is essential for downstream ecosystems, including the Colorado River Delta and the Gulf of California. The plant's operations support water reuse and aquifer recharge initiatives in the water-scarce region.

The plant discharges into the Salt River, which flows into the Gila River and then the Colorado River, ultimately reaching the Gulf of California. This watershed supports diverse aquatic life and is a critical water source for agriculture and urban areas in the arid Southwest. The Colorado River Basin is ecologically sensitive, providing habitat for endangered species such as the southwestern willow flycatcher and the bonytail chub.