What is the address of Mackinac Island WWTP?

The address on the plant’s EPA facility record is Stonecliff Rd, Mackinac Island, MI 49757, in Mackinac County. Its coordinates are 45.8601, -84.6385. For some plants the record holds the utility’s mailing address rather than the plant gate.

How much wastewater does Mackinac Island WWTP treat?

Mackinac Island WWTP treats an average of 0.41 MGD.

What treatment technology does Mackinac Island WWTP use?

Klarifi has identified one treatment structure or unit process at the Mackinac Island facility. The full treatment train, with exact unit counts, is shown in Klarifi with a free account.

What is the NPDES permit for Mackinac Island WWTP?

The facility discharges under NPDES permit MI0026751, currently effective, expiring October 2028.

Is Mackinac Island WWTP in compliance?

Discharge monitoring reports show 131 violations at Mackinac Island WWTP in the last three years, 102 of them effluent limit exceedances. The full history is available in Klarifi.

Who operates Mackinac Island WWTP and how do I contact them?

Mackinac Island WWTP is a publicly owned treatment works in Mackinac Island, Michigan. Klarifi lists 1 verified decision-maker contact for this facility, available with a free trial.

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Mackinac Island WWTP

Stonecliff Rd, Mackinac Island, MI 49757 · Mackinac County · Publicly Owned Treatment Works

Average flow: 0.41 MGD

Design flow: —

NPDES permit: MI0026751; Effective

Permit expires: October 2028

Population served: 482; CWNS 2022

Mackinac Island WWTP is a publicly owned wastewater treatment works in Mackinac Island, Mackinac County, Michigan treating an average of 0.41 million gallons per day, serving about 482 residents. It discharges under NPDES permit MI0026751 (effective), which expires in October 2028, with 131 recorded violations in the last three years.

Treatment technology

One treatment structure or unit process identified at Mackinac Island WWTP.

Available with a free Klarifi account

See the full treatment train at Mackinac Island WWTP: structures, unit processes and planned upgrades, with exact unit counts.

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Compliance snapshot (last 3 years)

Total violations: 131

Effluent violations: 102

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

Key contacts

1 verified contact for Mackinac Island WWTP, with validated emails and direct phone numbers.

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

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Nearby wastewater treatment plants in Michigan

St Ignace WWTP

Saint Ignace · 6 mi away

0.71 MGD

Mackinaw City WWTP

Mackinaw City · 8 mi away

0.27 MGD

Brevort Township Wwsl

Moran · 13 mi away

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Cheboygan WWTP

Cheboygan · 16 mi away

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Rudyard Twp Wwsl

Rudyard · 25 mi away

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Kinross Twp WWTP

Kincheloe · 29 mi away

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Petoskey WWTP

Petoskey · 37 mi away

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Superior Twp Wwsl

Brimley · 37 mi away

0.91 MGD

Mackinac Island 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 October 26, 2026; facility record last updated May 19, 2025.

Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Equalization tank · Centrate · all terms

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