New Haven County Lake Quality
Connecticut, 6 lakes, average grade B (Good)
Only 6 lakes in New Haven County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. With an average grade of B, New Haven County sits comfortably above the Connecticut median.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Lake Quassapaug (B); the most-stressed is Quonnipaug Lake (C).
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Quick Answers for New Haven County
Planning a trip? Check special fishing regulations for Lake Quassapaug — or check the official Connecticut fishing regulations.
All Lakes in New Haven County
6 lakes · 2 graded, 4 not rated2 graded lakes · 4 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | BLake QuassapaugNew Haven | B | No recent samples | 15.5 µg/L | 2.9 µg/L | No recent samples | Not recorded |
| 2 | CQuonnipaug LakeNew Haven | C | No recent samples | 22 µg/L | 2.7 µg/L | No recent samples | Not recorded |
| NRHitchcock LakeNew Haven | NR | 4.8 ft | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRNorth Farms ReservoirNew Haven | NR | 6.6 ft | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRTracys PondNew Haven | NR | 2 ft | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRWest LakeNew Haven | NR | 5.2 ft | No recent samples | No recent samples | No recent samples | Not recorded |
NR = not rated: the monitoring record does not meet the evidence bar for a grade. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.
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Other Counties in Connecticut
See how New Haven County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 49 states and 2 Canadian provinces.
Source: EPA National Aquatic Resource Surveys, 2026.