What is the NPDES permit for Mason WWTP?

The facility discharges under NPDES permit IA0077305, currently effective, expiring May 2029.

Is Mason WWTP in compliance?

Discharge monitoring reports show 6 violations at Mason WWTP in the last three years, 6 of them effluent limit exceedances. The full history is available in Klarifi.

Who operates Mason WWTP and how do I contact them?

Mason WWTP is a publicly owned treatment works in Mason City, Iowa. Klarifi lists 5 verified decision-maker contacts for this facility, available with a free trial.

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Mason WWTP

Q: What treatment technology does Mason WWTP use?

Klarifi has identified clarifiers, uncovered lagoons, biogas silos, biogas balloons at the Mason City facility.

Mason City, IA · Cerro Gordo County · Publicly Owned Treatment Works

Average flow: —

Design flow: —

NPDES permit: IA0077305; Effective

Permit expires: May 2029

Population served: 30,353; CWNS 2022

Mason WWTP is a publicly owned wastewater treatment works in Mason City, Cerro Gordo County, Iowa, serving about 30,353 residents. Treatment on site includes clarifiers, uncovered lagoons, biogas silos, biogas balloons. It discharges under NPDES permit IA0077305 (effective), which expires in May 2029, with 6 recorded violations in the last three years.

Treatment technology

Treatment structures identified at this facility. Exact unit counts are available in Klarifi.

Clarifiers

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Uncovered lagoons

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Biogas silos

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Biogas balloons

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Compliance snapshot (last 3 years)

Total violations: 6

Effluent violations: 6

Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.

Key contacts

5 verified contacts for Mason WWTP, with validated emails and direct phone numbers.

Unlock 5 verified contacts (2 more than shown)

Names, validated emails and direct phone numbers for decision-makers at Mason WWTP, plus the full compliance history and discharge data.

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Mason 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 March 20, 2025.

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