Benton County Lake Quality
Minnesota, 2 lakes, average grade F (Very Poor)
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. Unnamed Lake (F) is the cleanest in the county.
Quick Answers for Benton County
Planning a trip? Check special fishing regulations for Unnamed 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 →
- —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
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Unnamed Lake | F | 1.5 ft | - | - |
| 2 | Little Rock Lake | F | 2 ft | 17 ft | 156.5 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.