Marshall County Lake Quality
Minnesota, 2 lakes, average grade (Not rated)
Marshall 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.
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. Wb-A Agassiz Nwr Lake (—) is the cleanest in the county.
Quick Answers for Marshall County
Planning a trip? Check special fishing regulations for Wb-A Agassiz Nwr Lake — or browse the full Minnesota regulations index.
All Lakes in Marshall County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Wb-A Agassiz Nwr Lake | - | - | |
| 2 | Wb-B Agassiz Nwr Lake | - | - |
Other Counties in Minnesota
See how Marshall County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 36 states and 2 Canadian provinces.
Where to stay near Marshall County
Top-rated places to stay near Marshall County
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Source: EPA National Aquatic Resource Surveys, 2026.