Clay County Lake Quality
Minnesota, 2 lakes, average grade A (Excellent)
Clay County has 2 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's average grade is A — among the cleanest in Minnesota. 1 lakes pull an A on their own, and almost none fall into the D or F brackets.
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 Barnesville Lake (A); the most-stressed is Barnesville Lake (A).
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Quick Answers for Clay County
Planning a trip? Check special fishing regulations for Barnesville Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Minnesota regulations index.
DNR Reports (2)
Minnesota DNR LakeFinder resources for lakes in Clay County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — BarnesvilleFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — BarnesvilleFish Stocking History · MN DNR LakeFinder
All Lakes in Clay County
2 lakes · 1 graded, 1 not rated1 graded lake · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | ABarnesville LakeClay | A | No recent samples | 16.5 µg/L | 2.9 µg/L | No recent samples | 17 ft | Carry-in |
| NRBjorndahl LakeClay | NR | 2.3 ft | No recent samples | No recent samples | No recent samples | No recent samples | ✓ Public |
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 Minnesota
See how Clay County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 39 states and 2 Canadian provinces.
Source: EPA National Aquatic Resource Surveys, 2026.