Grafton County Lake Quality
New Hampshire, 35 lakes, average grade B (Good)
Grafton County's 35 graded lakes fall in the moderate-density bracket for New Hampshire. The county-level average smooths over real differences — a single agricultural watershed near the southwest corner can pull the average down even if the rest of the county runs clean. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.
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 Armington Lake-Deep Spot (A); the most-stressed is Gardner Lake-Deep Spot (C).
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Quick Answers for Grafton County
Planning a trip? Check special fishing regulations for Armington Lake-Deep Spot — or check the official New Hampshire fishing regulations.
All Lakes in Grafton County
35 lakes · 23 graded, 12 not rated23 graded lakes · 12 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | AArmington Lake-Deep SpotGrafton | A | No recent samples | 6.3 µg/L | 1.1 µg/L | No recent samples | Not recorded |
| 2 | ACanaan Street Lake-Deep SpotGrafton | A | No recent samples | 6.4 µg/L | 2 µg/L | No recent samples | Not recorded |
| 3 | AGoose Pond-Deep SpotGrafton | A | No recent samples | 10.8 µg/L | 3 µg/L | No recent samples | Not recorded |
| 4 | AKilton Pond-Deep SpotGrafton | A | No recent samples | 11.3 µg/L | 4.2 µg/L | No recent samples | Not recorded |
| 5 | ALake Tarleton-Deep SpotGrafton | A | No recent samples | 6.3 µg/L | 1.9 µg/L | No recent samples | Not recorded |
| 6 | ASpectacle Pond-Deep SpotGrafton | A | No recent samples | 13.9 µg/L | 4.1 µg/L | No recent samples | Not recorded |
| 7 | AStinson Lake-Deep SpotGrafton | A | No recent samples | 5.2 µg/L | 1.6 µg/L | No recent samples | Not recorded |
| 8 | BDodge Pond-Deep SpotGrafton | B | No recent samples | 14.1 µg/L | 8.5 µg/L | No recent samples | Not recorded |
| 9 | BDodge Pond-InletGrafton | B | No recent samples | 12.1 µg/L | No recent samples | No recent samples | Not recorded |
| 10 | BLake Katherine-Deep SpotGrafton | B | No recent samples | 7.6 µg/L | 10.7 µg/L | No recent samples | Not recorded |
| 11 | BLoon Lake-Deep SpotGrafton | B | No recent samples | 10.8 µg/L | 4.8 µg/L | No recent samples | Not recorded |
| 12 | BNewfound Lake-Deep SpotGrafton | B | No recent samples | 5.1 µg/L | No recent samples | No recent samples | Not recorded |
| 13 | BPost Pond-Deep SpotGrafton | B | No recent samples | 13.1 µg/L | 6.8 µg/L | No recent samples | Not recorded |
| 14 | BReservoir Pond-Deep SpotGrafton | B | No recent samples | 10.4 µg/L | 5 µg/L | No recent samples | Not recorded |
| 15 | BSouth Mountain Lake-CoveGrafton | B | No recent samples | 9.7 µg/L | No recent samples | No recent samples | Not recorded |
| 16 | BSouth Mountain Lake-Deep SpotGrafton | B | No recent samples | 12 µg/L | 5.1 µg/L | No recent samples | Not recorded |
| 17 | BSouth Mountain Lake-OutletGrafton | B | No recent samples | 9.7 µg/L | No recent samples | No recent samples | Not recorded |
| 18 | BSpectacle Pond-VlapGrafton | B | No recent samples | 7.8 µg/L | 2.7 µg/L | No recent samples | Not recorded |
| 19 | BWhite Oak PondGrafton | B | No recent samples | 14.5 µg/L | No recent samples | No recent samples | Not recorded |
| 20 | CGardner Lake-Deep SpotGrafton | C | No recent samples | 16.2 µg/L | 5.8 µg/L | No recent samples | Not recorded |
| 21 | CMooney-Clark Public Landing LakeGrafton | C | No recent samples | 16.2 µg/L | No recent samples | No recent samples | Not recorded |
| 22 | CPartridge Lake-Deep SpotGrafton | C | No recent samples | 16.9 µg/L | 6.4 µg/L | No recent samples | Not recorded |
| 23 | CRound Pond-Deep SpotGrafton | C | No recent samples | 18.9 µg/L | 8.3 µg/L | No recent samples | Not recorded |
| NRBath Covered Bridge LakeGrafton | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRBeaver Pond-Deep SpotGrafton | NR | No recent samples | 14.2 µg/L | No recent samples | No recent samples | Not recorded | |
| NRBranch PondGrafton | NR | No recent samples | 14.3 µg/L | No recent samples | No recent samples | Not recorded | |
| NRDodge Pond-BeachGrafton | NR | No recent samples | 33.3 µg/L | No recent samples | No recent samples | Not recorded | |
| NREcho Lake-Deep SpotGrafton | NR | No recent samples | 5 µg/L | 2.9 µg/L | No recent samples | Not recorded | |
| NRFrench Pond-Deep SpotGrafton | NR | No recent samples | 23.7 µg/L | No recent samples | No recent samples | Not recorded | |
| NRHarveys LakeGrafton | NR | No recent samples | 89.5 µg/L | No recent samples | No recent samples | Not recorded | |
| NRNorth Mountain Lake-BeachGrafton | NR | No recent samples | 9.2 µg/L | No recent samples | No recent samples | Not recorded | |
| NRPost Pond-Town BeachGrafton | NR | No recent samples | 10.3 µg/L | No recent samples | No recent samples | Not recorded | |
| NRSawyer Pond-Deep SpotGrafton | NR | No recent samples | 5 µg/L | No recent samples | No recent samples | Not recorded | |
| NRSouth Mountain Lake-BeachGrafton | NR | No recent samples | 9.7 µg/L | No recent samples | No recent samples | Not recorded | |
| NRStinson Lake-Near OutletGrafton | NR | No recent samples | 5.2 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
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Source: EPA National Aquatic Resource Surveys, 2026.