Hunterdon County Lake Quality
New Jersey, 3 lakes, average grade B (Good)
Hunterdon County has 3 graded lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. With an average grade of B, Hunterdon County sits comfortably above the New Jersey 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 Round Valley Reservoir (A); the most-stressed is Cushetunk Lake (D).
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Quick Answers for Hunterdon County
Planning a trip? Check special fishing regulations for Round Valley Reservoir — or check the official New Jersey fishing regulations.
All Lakes in Hunterdon County
3 lakes · 2 graded, 1 not rated2 graded lakes · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | ARound Valley ReservoirHunterdon | A | 26.9 ft | 7 µg/L | 1.3 µg/L | No recent samples | Not recorded |
| 2 | DCushetunk LakeHunterdon | D | 0.8 ft | 81.8 µg/L | 27.3 µg/L | No recent samples | Not recorded |
| NRRound Valley Intake PondHunterdon | NR | No recent samples | 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.
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Other Counties in New Jersey
See how Hunterdon 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.