
Grant County Lake Quality
Kentucky, 4 lakes, average grade C (Fair)
Grant County holds 4 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. 3 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. Grant County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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 Corinth Lake (C); the most-stressed is Boltz Lake (D).
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Quick Answers for Grant County
Planning a trip? Check special fishing regulations for Corinth Lake — or check the official Kentucky fishing regulations.
All Lakes in Grant County
4 lakes · 3 graded, 1 not rated3 graded lakes · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | CCorinth LakeGrant | C | No recent samples | 30 µg/L | No recent samples | No recent samples | ✓ Public |
| 2 | CWilliamstown LakeGrant | C | No recent samples | 30 µg/L | No recent samples | No recent samples | ✓ Public |
| 3 | DBoltz LakeGrant | D | No recent samples | 37.3 µg/L | No recent samples | No recent samples | ✓ Public |
| NRWilliamstown LakeGrant | NR | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public |
NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.
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Other Counties in Kentucky
See how Grant County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..
Source: EPA National Aquatic Resource Surveys, 2026.