Oak Harbor WWTP
355 E Water St, Oak Harbor, OH 43449 · Ottawa County · Publicly Owned Treatment Works
- Average flow
- 0.86 MGD
- Design flow
- 0.93 MGD
- NPDES permit
- OH0026841
- Effective
- Permit expires
- December 2028
- Population served
- 4,129
- CWNS 2022
Oak Harbor WWTP is a publicly owned wastewater treatment works in Oak Harbor, Ottawa County, Ohio treating an average of 0.86 million gallons per day against a permitted design capacity of 0.93 MGD, serving about 4,129 residents. It discharges under NPDES permit OH0026841 (effective), which expires in December 2028, with 120 recorded violations in the last three years. EPA has recorded 1 formal enforcement action naming the plant, the latest in March 2026.
Treatment technology
3 treatment structures and unit processes identified at Oak Harbor WWTP.
Available with a free Klarifi account
See the full treatment train at Oak Harbor WWTP: structures, unit processes and planned upgrades, with exact unit counts.
Compliance snapshot (last 3 years)
- Total violations
- 120
- Effluent violations
- 82
Based on NPDES Discharge Monitoring Reports. Full violation history, parameters and discharge data available in the Klarifi platform.
EPA enforcement history
Federal civil enforcement cases, compliance inspections and informal actions recorded for Oak Harbor WWTP in EPA's ICIS system.
- Formal actions
- 1
- 1 since FY2020
- Compliance actions
- $34M
- required by EPA orders
- EPA inspections
- 0
- none on record
Latest case · Mar 2026
Oak Harbor WWTP AOC
Administrative order · CWA, NPDES Permit Violations · Final Order Issued · Compliance actions $34M
Source: EPA ECHO, civil enforcement case 05-2026-0313.
Full case history with a free Klarifi account
Every action against Oak Harbor WWTP with dates, milestones, violation types and EPA's complete case summaries, plus inspections and informal actions.
Key contacts
Decision-makers at Oak Harbor WWTP.
No verified contacts on file yet
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Nearby wastewater treatment plants in Ohio
Oak Harbor · 1 mi away
0.0048 MGD
Oak Harbor · 6 mi away
0.0059 MGD
Lindsey · 7 mi away
0.06 MGD
Elmore · 8 mi away
0.2 MGD
Port Clinton · 10 mi away
1.93 MGD
Fremont · 10 mi away
7.22 MGD
Genoa · 11 mi away
0.32 MGD
Woodville · 11 mi away
0.24 MGD
Oak Harbor 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 November 15, 2025.
Wastewater terms: POTW · MGD · NPDES permit · Inflow and infiltration · Activated sludge · Oxidation ditch · all terms