Mackay WWTP
Mackay, ID · Custer County · Publicly Owned Treatment Works
- Average flow
- 0.07 MGD
- Design flow
- 0.18 MGD
- NPDES permit
- ID0023027
- Administratively continued
- Permit expires
- May 2023
- Population served
- 608
- CWNS 2022
Mackay WWTP is a publicly owned wastewater treatment works in Mackay, Custer County, Idaho treating an average of 0.07 million gallons per day against a permitted design capacity of 0.18 MGD, serving about 608 residents. Treatment on site includes uncovered lagoons. It discharges under NPDES permit ID0023027 (administratively continued), which expires in May 2023, with 5 recorded violations in the last three years.
Treatment technology
Treatment structures identified at this facility. Exact unit counts are available in Klarifi.
Uncovered lagoons
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Compliance snapshot (last 3 years)
- Total violations
- 5
- Effluent violations
- 5
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
Key contacts
1 verified contact for Mackay WWTP, with validated emails and direct phone numbers.
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Names, validated emails and direct phone numbers for decision-makers at Mackay WWTP, plus the full compliance history and discharge data.
Nearby wastewater treatment plants in Idaho
Ketchum · 41 mi away
1.02 MGD
Carey · 46 mi away
—
Richfield · 65 mi away
—
Fairfield · 71 mi away
—
Roberts · 75 mi away
0.04 MGD
Aberdeen · 77 mi away
0.2 MGD
Shoshone · 77 mi away
0.13 MGD
Shelley · 81 mi away
1.93 MGD
Mackay WWTP: frequently asked 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 September 11, 2026; facility record last updated August 5, 2026.