Plymouth Reservoir
Chenango County, New York77 acresView mapDirections
Not Rated: one monitoring station 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.
- Impaired · Nutrients (phosphorus, nitrogen)
- 23 ft max depth
- Limited data
Plymouth Reservoir in Chenango County, New York is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6.2 ft visibility. Surface area: 77 acres.
- Clarity
- 6.2 ft
- Max depth
- ~23 ft est.
- Area
- 77 acres
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Watch Plymouth Reservoir’s letter
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Why Plymouth Reservoir has no grade
Plymouth Reservoir has monitoring on record from one station, 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, Plymouth Reservoir is Not Rated — not an F. Its 6.2-foot median from 8 readings collected 2020 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 NYSDEC and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
Plymouth Reservoir is a 77-acre lake in Chenango County, New York with an estimated average depth of about 23 feet.
Source: EPA Water Quality Portal sampling records, NYSDEC, last sampled 2020-09-12. Grade methodology: LakeQuality methodology.
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Plymouth Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
Water quality measurements for Plymouth Reservoir
These readings exist but are not enough for an A–F grade — see why.
Murky, only visible to about 6.2 ft. TSI 51.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.2 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 51 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | ~23 ft est. |
| Average Depth | ~14 ft est. |
| Surface Area | 77 acres |
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. New York has not published bathymetry for Plymouth Reservoir.
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.
Fishing Plymouth Reservoir
Reservoir Info (USACE NID)
Plymouth Reservoir is a man-made reservoir impounded by the Plymouth Reservoir Dam (completed 1827), built primarily for recreation on the RESERVOIR CREEK; rockfill-type dam, 12 ft tall and 150 ft long.
- Surface area
- 77 ac
- Normal storage
- 320 ac-ft
- Max storage
- 400 ac-ft
- Drainage area
- 1.05 sq mi
- Hazard class
- Significant
- Owner
- PLYMOUTH RESERVOIR ASSOCIATION
Source: USACE National Inventory of Dams, NID ID NY01481 · Operator website
EPA Impairment Status
Plymouth Reservoir is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit NY0602-0014 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Plymouth Reservoir under Clean Water Act (NPDES) discharge permits.
- Camp PharsaliaPharsalia · 5 mi away · NPDES NY0103781
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.
Nearby Lakes in Chenango County
Frequently asked questions about Plymouth Reservoir
Where is Plymouth Reservoir?
- Plymouth Reservoir is a lake in Chenango County, New York. 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 Plymouth Reservoir?
- Plymouth Reservoir in Chenango County, New York is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 6.2 ft visibility. Surface area: 77 acres.
Is Plymouth Reservoir safe to swim in?
- The letter is not a swimming clearance. Plymouth Reservoir is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen). Check local advisories before you swim.
How deep is Plymouth Reservoir?
- No published bathymetric survey covers Plymouth Reservoir, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 23 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 77 acres.
Explore Plymouth Reservoir across LakeQuality
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Where this data comes from
8 measurements from 1 monitoring station, 2020. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- North American Lake Management Society
NALMS8 samples · 2020
Monitoring station identifiers (1)
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
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)