Mason County Lake Quality
Michigan, 6 lakes, average grade B (Good)
Mason County has 6 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. The county-wide average lands at B — solid water quality with most lakes carrying clear summer transparency and low-to-moderate phosphorus.
A meaningful share of Mason's lakes break 50 feet of depth, which matters because deep lakes hold cooler water all summer and resist the resuspended-sediment problems that plague shallow basins. The county's best-graded lake is Gun Lake (A).
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Quick Answers for Mason County
Planning a trip? Check special fishing regulations for Gun Lake, whether the fish are safe to eat, and the best times to fish — or check the official Michigan fishing regulations.
Fishing in Mason County
All Lakes in Mason County
6 lakes · 3 graded, 3 not rated3 graded lakes · 3 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | AGun LakeMason | A | 14 ft | 9 µg/L | 2.2 µg/L | No recent samples | 22 ft | ✓ Public |
| 2 | CUpper Hamlin LakeMason | C | 6 ft | 29 µg/L | 6.2 µg/L | No recent samples | No recent samples | Not recorded |
| 3 | CLower Hamlin LakeMason | C | 11.5 ft | 26 µg/L | 3.3 µg/L | No recent samples | No recent samples | ✓ Public |
| NRHamlin LakeMason | NR | 9 ft | No recent samples | No recent samples | No recent samples | 65 ft | ✓ Public | |
| NRChancellor LakeMason | NR | 26 ft | No recent samples | No recent samples | No recent samples | 50 ft | Not recorded | |
| NRHoags LakeMason | NR | 11.5 ft | No recent samples | No recent samples | No recent samples | 18 ft | ✓ 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.
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 Michigan
See how Mason 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.