Pattaconk Reservoir
Middlesex County, Connecticut56 acresView mapDirections
CT DEEP publishes the water-quality measurements for Pattaconk Reservoir. Here is what has been measured.
- Mesotrophic
- Limited data
Pattaconk Reservoir in Middlesex County, Connecticut has water-quality measurements published by CT DEEP, shown here as reported. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 2.8 µg/L. Surface area: 55.5 acres.
Pattaconk Reservoir is a 56-acre mesotrophic lake in Middlesex County, Connecticut. Compared to the 4 other monitored lakes in Middlesex County, Pattaconk Reservoir ranks #3 for water quality.
Source: EPA Water Quality Portal sampling records, your state environmental agency, last sampled 2023-07-13. Methodology: how these readings are compared.
Swimming conditions
Readings onlyLimited data
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. Check local advisories before you swim.
Whether Pattaconk Reservoir 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 Pattaconk Reservoir
These are the measurements CT DEEP publishes for Pattaconk Reservoir, 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 16 µg/L. Chlorophyll-a 2.8 µg/L. TSI 42.
| 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 | 16µg/L | Good GoodFairPoor |
| Chlorophyll-a (algae) | 2.8µg/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. | 42 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Pattaconk Reservoir
Answers come straight from the public measurements and survey records on this page.
Lake Details
Surface area
56 acres
No bathymetric survey has been published for Pattaconk Reservoir, so its depth is not documented here.
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Reservoir Info (USACE NID)
Pattaconk Reservoir is a man-made reservoir impounded by the Pattaconk Reservoir Dam (completed 1932), built primarily for recreation on the Pattaconk Brook; earth-type dam, 23 ft tall and 416 ft long.
- Surface area
- 55.5 ac
- Normal storage
- 772 ac-ft
- Max storage
- 824 ac-ft
- Drainage area
- 1.9 sq mi
- Hazard class
- High
- Owner
- Connecticut DEEP
Source: USACE National Inventory of Dams, NID ID CT00398 · Operator website
Nearby Lakes in Middlesex County
Frequently asked questions about Pattaconk Reservoir
Where is Pattaconk Reservoir?
- Pattaconk Reservoir is a lake in Middlesex County, Connecticut. Its water-quality measurements are published by CT DEEP and shown on this page as reported.
What is the water quality of Pattaconk Reservoir?
- Pattaconk Reservoir in Middlesex County, Connecticut has water-quality measurements published by CT DEEP, shown here as reported. Phosphorus: 16 µg/L. Chlorophyll-a (algae): 2.8 µg/L. Surface area: 55.5 acres.
Is Pattaconk Reservoir safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Check local advisories before you swim.
Explore Pattaconk Reservoir across LakeQuality
More lakes in Connecticut
Other Lakes in Connecticut
Mesotrophic Lakes in Connecticut
Where this data comes from
10 measurements from 1 monitoring station, 2023. Retrieved from the EPA Water Quality Portal on 2026-08-21.
Collected and reported by
- Connecticut Department Of Energy And Environmental Protection
CT_DEP01_WQX10 samples · 2023
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.