Oxidation ditches: wastewater treatment plants in Arizona
14 plants · 25% of the state · 92 MGD reported by 6 plants
Klarifi identifies 14 publicly owned wastewater treatment plants with oxidation ditches in Arizona, 25% of the 56 plants in the state (92 MGD reported by 6 plants). The largest is 91st Avenue WWTP in Tolleson at 83.69 MGD.
Oxidation ditches are ring-shaped activated sludge reactors with long retention times, common at plants between 0.5 and 10 MGD. They are recognisable from the air by their looped channels and rely on surface aerators or brush rotors, which are frequent replacement and energy-efficiency projects.
The largest oxidation ditch plants in Arizona
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | 91st Avenue WWTP | Tolleson | 83.69 | AZ0020524 | Apr 2028 | 2 |
| 2 | Goodyear, City Of - 157th Ave WWTP | Goodyear | 2.9 | AZ0022357 | Mar 2027 | 1 |
| 3 | Town Of Prescott Valley - WWTP | Prescott Valley | 2.69 | AZ0025381 | Feb 2027 | 0 |
| 4 | Buckeye WWTP | Buckeye | 1.91 | AZ0025313 | Oct 2030 | 1 |
| 5 | City Of Safford - Gila Resources Wrp | Safford | 0.72 | AZ0024911 | Jun 2029 | 0 |
| 6 | City Of Tombstone - WWTP | Tombstone | 0.05 | AZ0025577 | Mar 2031 | 11 |
| 7 | Benson, City Of - WWTF | Benson | — | AZ0026026 | Oct 2031 | 0 |
| 8 | Bullhead City, City Of - Section 10 WWTP | Bullhead City | — | AZ0026808 | Oct 2026 | 0 |
| 9 | Casa Grande WRF | Casa Grande | — | AZ0025178 | Sep 2029 | 28 |
| 10 | City Of Williams - WWTP | Williams | — | AZ0025755 | Oct 2029 | 0 |
Contacts and project signals for every plant on this list
Klarifi adds verified decision-maker contacts, permit limits, discharge monitoring data and the capital projects planned in each city, filterable by technology, size and compliance record.
Other technologies in Arizona
Oxidation ditches in other states
Oxidation ditches in Arizona: questions
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed October 26, 2026.
Wastewater terms: Oxidation ditch · Activated sludge · Biological nutrient removal · Tertiary treatment · Significant industrial user · all terms