Coos County Lake Quality
New Hampshire, 15 lakes, average grade B (Good)
There are 15 graded lakes in Coos County. The mix is varied enough that the county-level average tells you the broad strokes, not the choose-this-cabin specifics. With an average grade of B, Coos County sits comfortably above the New Hampshire 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 Akers Pond-Deep Spot (B); the most-stressed is Martin Meadow Pond-Deep Spot (C).
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Quick Answers for Coos County
Planning a trip? Check special fishing regulations for Akers Pond-Deep Spot — or check the official New Hampshire fishing regulations.
All Lakes in Coos County
15 lakes · 13 graded, 2 not rated13 graded lakes · 2 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | BAkers Pond-Deep SpotCoos | B | No recent samples | 9 µg/L | No recent samples | No recent samples | Not recorded |
| 2 | BBig Dummer Pond-Deep SpotCoos | B | No recent samples | 10.5 µg/L | No recent samples | No recent samples | Not recorded |
| 3 | BForest Lake-Deep SpotCoos | B | No recent samples | 10 µg/L | 4.6 µg/L | No recent samples | Not recorded |
| 4 | BForest Lake-FinkelCoos | B | No recent samples | 10.6 µg/L | No recent samples | No recent samples | Not recorded |
| 5 | BForest Lake-Newt CottageCoos | B | No recent samples | 7.7 µg/L | No recent samples | No recent samples | Not recorded |
| 6 | BForest Lake-Sundman CottageCoos | B | No recent samples | 8.9 µg/L | No recent samples | No recent samples | Not recorded |
| 7 | BJericho Lake-Deep SpotCoos | B | No recent samples | 13 µg/L | No recent samples | No recent samples | Not recorded |
| 8 | BLittle Dummer Pond-Deep SpotCoos | B | No recent samples | 9.6 µg/L | No recent samples | No recent samples | Not recorded |
| 9 | BMartin Meadow Pond-MccartenCoos | B | No recent samples | 6.5 µg/L | No recent samples | No recent samples | Not recorded |
| 10 | BMartin Meadow Pond-WeeksCoos | B | No recent samples | 6.6 µg/L | No recent samples | No recent samples | Not recorded |
| 11 | BMartin Meadow Pond-WhithedCoos | B | No recent samples | 5.6 µg/L | No recent samples | No recent samples | Not recorded |
| 12 | BStratford Bog Pond-Deep SpotCoos | B | No recent samples | 8.8 µg/L | No recent samples | No recent samples | Not recorded |
| 13 | CMartin Meadow Pond-Deep SpotCoos | C | No recent samples | 17.1 µg/L | 3.1 µg/L | No recent samples | Not recorded |
| NRBurns Pond-Deep SpotCoos | NR | No recent samples | 13.6 µg/L | 5.5 µg/L | No recent samples | Not recorded | |
| NRFirst Connecticut Lake-Deep SpotCoos | NR | No recent samples | 7.4 µg/L | 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 New Hampshire
See how Coos 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.