Clear Fork Reservoir is a 1,024-acre productive, nutrient-rich eutrophic lake in Morrow County, Ohio. Water quality is graded F based on 1 sampling years through 2021. Limited fish-species data available. Public access is available with 1 public boat landing.
Source: EPA Water Quality Portal sampling records, Ohio DNR, last sampled 2021-10-14. Grade methodology: LakeGrade methodology.
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Clear Fork Reservoir Water Quality Report Card (2026)
A printable one-page report card for Clear Fork Reservoir: grade, clarity, phosphorus, algae, multi-year trend, depth, and fish — with sources.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 3.1 ft of visibility. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.1 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 1,024 acres |
| Public Access | Yes |
Where to stay near Clear Fork Reservoir
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Fishing Clear Fork Reservoir
Recreation & Access
Current Conditions
Latest reading Oct 1, 2020, 4:45 AM from USGS gauge 03131898. See live data ↗ — readings update every 15–60 minutes; this page refreshes on each build.
Location & Depth Map
Free interactive depth-contour map of Clear Fork Reservoir, reaching a maximum surveyed depth of 24 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Ohio DNR.
County Ranking
Ranked #1 of 1 lakes in Morrow County
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Explore Clear Fork Reservoir across LakeGrade
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Other Grade F Lakes in Ohio
Eutrophic Lakes in Ohio
More records, surveys & data sources
Reservoir Info (USACE NID)
Clear Fork Reservoir is a man-made reservoir impounded by the Clear Fork Reservoir Dam (completed 1949), built primarily for water supply on the CLEAR FORK MOHICAN RIVER; earth-type dam, 44 ft tall and 3,420 ft long.
- Surface area
- 1,024 ac
- Normal storage
- 10,922 ac-ft
- Max storage
- 26,532 ac-ft
- Drainage area
- 34.67 sq mi
- Hazard class
- High
- Owner
- City of Mansfield
All listed purposes: Water Supply;Recreation.
Source: USACE National Inventory of Dams, NID ID OH00778 · Operator website
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
10 EPA-permitted facilities operate within about 5 miles of Clear Fork Reservoir under Clean Water Act (NPDES) discharge permits, including 1 classified by the EPA as major discharger. 6 facilities have a reported Clean Water Act violation in the past three years.
- Village Of Lexington WwtpLexington · 3.5 mi away · NPDES OH0020257MajorRecent violation
- Mid-Ohio Sports Car CourseLexington · 1.1 mi away · NPDES OH0136565Recent violation
- Mansfield WtpMansfield · 2.4 mi away · NPDES OH0003867Recent violation
- Hamilton Standard Controls United TechnologiesLexington · 2.8 mi away · NPDES OH0095281Recent violation
- Cole Tooling & StampingOntario · 4.3 mi away · NPDES OH0138797Recent violation
- Cedar Creek Mhp LlcLexington · 4.8 mi away · NPDES OH0138509Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2021-10-14
Monitoring stations: 4