Willcox, Arizona, USA

Wastewater Treatment Plant Improvements in Willcox, Arizona

Status: Completed


The City of Willcox provides natural gas, drinking water and wastewater service to its residents. The City’s Public Works Department operates and maintains the sanitary sewer collection system and the Municipal Wastewater Treatment Plant (WWTP).

The WWTP has a treatment capacity of 0.6 million gallons per day
(mgd) with a maximum monthly average flow rate of 0.474 mgd.
Currently, the WWTP is not in compliance with the effluent discharge
requirements of the Arizona Pollutant Discharge Elimination System
(AZPDES) permit and the Aquifer Protection Permit (APP) of the
Arizona Department of Environmental Quality (ADEQ) for fecal
coliforms, total suspended solids, nutrient removal and other pollutants. As a result of this noncompliance, ADEQ and the City have agreed to a consent order that requires the City to improve the performance of the WWTP.


The project consists of improvements to the WWTP by rehabilitating and
upgrading the plant from a lagoon system to an oxidation ditch process in
order to meet the City’s current and future needs. The project includes
the following components:

  • Headworks and influent pump station
  • Oxidation ditches
  • Secondary clarifiers
  • Blower/electrical building
  • Tertiary filtration
  • Disinfection
  • Effluent / non-potable water pump station
  • Sludge holding tank


The project will improve the quality of the effluent discharged to Cochise Lake, an impaired water body, as well as wastewater treatment service for 100% of the system's 1,032 existing residential wastewater connections, reducing any the health risks associated with
environmental deterioration and ground and surface water contamination. The upgraded facility will be in full compliance with all applicable laws, rules and regulations. Additionally, the project will allow the City to continue reusing the treated wastewater at the golf course, rather than potable water resources for that purpose.

Project Financing

Total Project Cost US 16.51M
NADBank Funding US 4.70M - NADBank Grant: BEIF
Other Funding Partners Border Environment Infrastructure