Arizona City Sanitary District Wastewater Treatment Plant, Eloy, Arizona

Arizona City Sanitary District is a municipal wastewater treatment plant serving the community of Eloy in Pinal County, Arizona. The plant handles wastewater from approximately 13,500 residents, placing it in the medium-agglomeration category for US facilities. As a US plant serving this population, it operates under the Clean Water Act and is subject to National Pollutant Discharge Elimination System (NPDES) permits issued by the Arizona Department of Environmental Quality. These permits set effluent limits to protect water quality in the receiving environment. The plant discharges treated wastewater into the local watershed, which drains into the Gila River basin and ultimately contributes to the Colorado River system. The arid climate of southern Arizona makes water reuse and effluent quality particularly important for downstream ecosystems and agricultural users.

The plant's discharge enters the Gila River watershed, a major tributary of the Colorado River. This region supports diverse desert riparian habitats and is critical for migratory birds. Downstream, the Colorado River flows to the Gulf of California, where water quality affects estuarine ecosystems. The arid environment makes treated effluent a valuable water resource for local wildlife and agriculture.