Lake Zoar
Fairfield County, ConnecticutView mapDirections
CT DEEP publishes the water-quality measurements for Lake Zoar. Here is what has been measured.
- Eutrophic
- Impaired · Algal growth
- Limited data
Lake Zoar in Fairfield County, Connecticut has water-quality measurements published by CT DEEP, shown here as reported. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 14.9 µg/L.
Lake Zoar is a productive, nutrient-rich eutrophic lake in Fairfield County, Connecticut. Compared to the 3 other monitored lakes in Fairfield County, Lake Zoar ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2022-08-16. Methodology: how these readings are compared.
Swimming conditions
Readings onlyBacteria advisory
Based on clarity and algae readings from past sampling — there is no live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Nutrient and algae readings are not a swimming clearance. Lake Zoar is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal), pCBs. Check local advisories before you swim.
Whether Lake Zoar 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 Zoar
These are the measurements CT DEEP publishes for Lake Zoar, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
No clarity data. Phosphorus 26 µg/L. Chlorophyll-a 14.9 µg/L. TSI 54.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | No reading How deep a black-and-white disk stays visible from the surface. Higher is clearer. | |
| Total phosphorus | 26µg/L | Fair GoodFairPoor |
| Chlorophyll-a (algae) | 14.9µg/L | Measured, not scored 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. | 54 | Eutrophic OligotrophicMesotrophicEutrophicHypereutrophic |
High nutrients, frequent algae, reduced clarity
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Answers come straight from the public measurements and survey records on this page.
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Fishing Lake Zoar
EPA Impairment Status
Lake Zoar is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Designated uses not supporting: Fish consumption, Recreation.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit CT6000-00-5+L2_01 · Official waterbody report
Nearby Lakes in Fairfield County
Frequently asked questions about Lake Zoar
Where is Lake Zoar?
- Lake Zoar is a lake in Fairfield 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 Zoar?
- Lake Zoar in Fairfield County, Connecticut has water-quality measurements published by CT DEEP, shown here as reported. Phosphorus: 26 µg/L. Chlorophyll-a (algae): 14.9 µg/L.
Is Lake Zoar safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Lake Zoar is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth, nutrients (phosphorus, nitrogen), pathogens (E. coli, fecal), pCBs. Check local advisories before you swim.
Explore Lake Zoar across LakeQuality
More lakes in Connecticut
Other Lakes in Connecticut
Eutrophic Lakes in Connecticut
Where this data comes from
20 measurements from 1 monitoring station, 2022. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Connecticut Department Of Energy And Environmental Protection
CT_DEP01_WQX20 samples · 2022
Analytical methods
- Total Phosphorus After Block Digestion
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- Nitrate-Nitrite Nitrogen by Colorimetry
- Turbidity by Nephelometry
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.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database