Lake Plymouth
Litchfield County, Connecticut46 acresView mapDirections
CT DEEP publishes the water-quality measurements for Lake Plymouth. Here is what has been measured.
- Limited data
Lake Plymouth in Litchfield County, Connecticut has water-quality measurements published by CT DEEP, shown here as reported. Water clarity: 3.5 ft visibility. Surface area: 45.5 acres.
Lake Plymouth is a 46-acre lake in Litchfield County, Connecticut.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2025-09-27. Methodology: how these readings are compared.
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Whether Lake Plymouth is safe to swim in today is a call for the Connecticut Department of Energy and Environmental Protection and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Lake Plymouth
These are the measurements CT DEEP publishes for Lake Plymouth, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Murky, only visible to about 3.5 ft. TSI 59.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 3.5ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 59 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
Ask about Lake Plymouth
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
46 acres
No bathymetric survey has been published for Lake Plymouth, so its depth is not documented here.
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Fishing Lake Plymouth
Reservoir Info (USACE NID)
Lake Plymouth is a man-made reservoir impounded by the Lake Plymouth Dam (completed 1900), built primarily for recreation on the Todd Hollow Bk Trib; earth-type dam, 11 ft tall and 331 ft long.
- Surface area
- 45.5 ac
- Normal storage
- 128 ac-ft
- Max storage
- 128 ac-ft
- Drainage area
- 0.35 sq mi
- Hazard class
- Significant
- Owner
- Lake Plymouth Community Assoc Inc.
Source: USACE National Inventory of Dams, NID ID CT00290 · Operator website
Nearby Lakes in Litchfield County
Frequently asked questions about Lake Plymouth
Where is Lake Plymouth?
- Lake Plymouth is a lake in Litchfield County, Connecticut. Its water-quality measurements are published by CT DEEP and shown on this page as reported.
What is the water quality of Lake Plymouth?
- Lake Plymouth in Litchfield County, Connecticut has water-quality measurements published by CT DEEP, shown here as reported. Water clarity: 3.5 ft visibility. Surface area: 45.5 acres.
Is Lake Plymouth safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
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Where this data comes from
8 measurements from 1 monitoring station, 2025. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- CT DEEP Volunteer Water Monitoring Program (Volunteer)
CTVOLMON8 samples · 2025
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.