Benton County Lake Quality
Minnesota, 2 lakes, average grade F (Algae-prone)
Only 2 lakes in Benton County carry an active grade. The county-level summary is therefore representative of those specific lakes, not necessarily of every water body in the county. The county average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.
Most of the county's monitored lakes are shallow — under 50 feet — which means wind keeps the water column mixed all summer and sediment-bound phosphorus releases back into the surface layer whenever the bottom is disturbed. Little Rock Lake (F) is the cleanest in the county.
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Quick Answers for Benton County
Planning a trip? Check special fishing regulations for Little Rock Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Minnesota regulations index.
DNR Reports (3)
Minnesota DNR LakeFinder resources for lakes in Benton County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — Little RockFisheries Lake Survey · MN DNR LakeFinder
- —Aquatic Plant Report — Little Rock (1980)Aquatic Plant Report · MN DNR LakeFinder
- —Public Water Access Sites — Little RockPublic Water Access Sites · MN DNR LakeFinder
All Lakes in Benton County
2 lakes · 1 graded, 1 not rated1 graded lake · 1 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | FLittle Rock LakeBenton | F | 1.8 ft | 156.5 µg/L | 115 µg/L | No recent samples | 17 ft | ✓ Public |
| NRUnnamed LakeBenton | NR | 1.5 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
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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 Benton 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.