Warren County Lake Quality
New Jersey, 3 lakes, average grade D (Nutrient-rich)
Warren 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. On average, Warren County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
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 Deer Park Pond (D); the most-stressed is Delaware Lake (F).
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Quick Answers for Warren County
Planning a trip? Check special fishing regulations for Deer Park Pond — or check the official New Jersey fishing regulations.
All Lakes in Warren County
3 lakes · 2 graded, 1 not rated2 graded lakes · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | DDeer Park PondWarren | D | 5.6 ft | 11.8 µg/L | 11.4 µg/L | No recent samples | Not recorded |
| 2 | FDelaware LakeWarren | F | 1.6 ft | 156.5 µg/L | 106.1 µg/L | No recent samples | Not recorded |
| NRCedar LakeWarren | 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 Warren 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.