Seneca Lake
Noble County, OhioView mapDirections
Not Rated: three monitoring stations are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- 60 ft max depth
- Public access
- Limited data
Seneca Lake in Noble County, Ohio is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.7 ft visibility.
- Clarity
- 1.7 ft
- Typical in September
- 76°F
- Max depth
- ~60 ft est.
- Public access
- Yes
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Watch Seneca Lake’s letter
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Why Seneca Lake has no grade
Seneca Lake has monitoring on record from three stations, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Seneca Lake is Not Rated — not an F. Its 1.7-foot median from 28 readings collected 2020–2021 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by Ohio EPA and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Seneca Lake is a lake in Noble County, Ohio with an estimated average depth of about 60 feet. Limited fish-species data available. Public access is available with 9 public boat landings.
Source: EPA Water Quality Portal sampling records, Ohio EPA, last sampled 2021-09-14. Grade methodology: LakeQuality methodology.
What Seneca Lake is good for
From access and monitoring records, not editorial picks.
- Boat launch9 documented ramps
- Camping4 public campgrounds nearby
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for Seneca Lake
These readings exist but are not enough for an A–F grade — see why.
Very murky, less than 1.7 ft of visibility. TSI 70.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.7 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 70 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Current Conditions
USGS snapshot Jul 6, 2026, 4:15 AM from gauge 03141000 (Senecaville Lake Near Senecaville OH). Station page ↗ — a live reading replaces this snapshot when the gauge responds. Missing live data is not an all-clear.
Water Temperature
Seneca Lake typically sits around 76°F at the surface in September. Summer average is about 79°F. Usually warmest in Jul (about 82°F) and coldest in May (about 71°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 182 field readings (2012–2021) via the EPA Water Quality Portal. See the full Seneca Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~60 ft est. |
| Average Depth | ~26 ft est. |
| Public Access | Yes |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Ohio has not published bathymetry for Seneca Lake.
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
Recreation & Access
- Guernsey County Sportsmen ClubPublic
- Lakeview Boat ClubPublic
- Noble County Fish and GamePublic
- Seneca Lake Park - Campground RampPublic
- Seneca Lake Park - Seneca Marina Pt. CampgroundPublic
- Seneca Launch RampPublic
Showing 6 of 9 documented landings from the USGS National Boat Ramps inventory.
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Public campgrounds near Seneca Lake
- Seneca Park Lake Woodlands Campground0.5 km
- Seneca Lake Park Parkside Central Campgroun0.8 km
- Seneca Lake Park Parkside Campground1.2 km
- Seneca Lake Park Marina Point Campground2.9 km
Nearest public campgrounds in the USGS National Map inventory, within about 3 miles. An empty list means USGS records no campground that close, which is not the same as camping being unavailable. Where the source gives an official reservation link, it is used; the cabin and hotel search does not cover campsites. More camping lakes
Fishing Seneca Lake
Regulated Pollution Sources Nearby
6 EPA-permitted facilities operate within about 5 miles of Seneca Lake under Clean Water Act (NPDES) discharge permits. 5 facilities have a reported Clean Water Act violation in the past three years.
- Lashley Addition WwtpCaldwell · 0.8 mi away · NPDES OH0144860Recent violation
- Buffalo Hills Campground StpSenecaville · 1.8 mi away · NPDES OH0135186Recent violation
- Senecaville WwtpSenecaville · 2.8 mi away · NPDES OH0041548Recent violation
- Lake Seneca Resorts AssocSenecaville · 2.9 mi away · NPDES OH0076414Recent violation
- Antrim Mennonite Activity CenterGuernsey · 3.7 mi away · NPDES OH0091375Recent violation
- Seneca Lake Camp AreaSenecaville · 3.7 mi away · NPDES OH0059102
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.
Graded lakes near Seneca Lake
Seneca Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Noble County
Frequently asked questions about Seneca Lake
Where is Seneca Lake?
- Seneca Lake is a lake in Noble County, Ohio. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Seneca Lake?
- Seneca Lake in Noble County, Ohio is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 1.7 ft visibility.
Is Seneca Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
What is the water temperature of Seneca Lake?
- Seneca Lake typically sits around 76°F at the surface in September, from 182 EPA Water Quality Portal field readings (2012–2021). That is a typical value for the month, not a live reading.
How deep is Seneca Lake?
- No published bathymetric survey covers Seneca Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 60 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
What is the water level at Seneca Lake?
- The USGS snapshot on this page for Seneca Lake is 833.28 ft of water-surface elevation, recorded Jul 6, 2026, 4:15 AM at gauge 03141000. Current Conditions hydrates a live NWIS reading from that same station when the gauge responds. A missed live fetch is not an all-clear.
Are there boat ramps on Seneca Lake?
- Seneca Lake has 9 documented boat landings in the USGS National Boat Ramps inventory. Named access points include Guernsey County Sportsmen Club, Lakeview Boat Club, Noble County Fish and Game, Seneca Lake Park - Campground Ramp, among others. Public access is listed as yes.
Are there campgrounds on Seneca Lake?
- Seneca Lake has 4 public campgrounds from USGS The National Map within 5 km, including Seneca Park Lake Woodlands Campground, Seneca Lake Park Parkside Central Campgroun, Seneca Lake Park Parkside Campground, Seneca Lake Park Marina Point Campground. This is a location join, not a booking. Cabins and hotels are listed separately; campsite reservations use the official link when the source provides one.
Explore Seneca Lake across LakeQuality
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Where this data comes from
28 measurements from 3 monitoring stations, 2020–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Ohio Lake Management Society (Volunteer)
OLMS28 samples · 2020–2021
Monitoring station identifiers (3)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Named boat-access points from the USGS National Boat Ramps inventory
Public campgrounds from USGS The National Map Structures, within about 3 miles