Monroe County Lake Quality
Missouri, 3 lakes, average grade D (Poor)
Only 3 lakes in Monroe 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. On average, Monroe County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
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. Monroe City Lake B Nr. Dam (C) is the cleanest in the county.
Quick Answers for Monroe County
Planning a trip? Check special fishing regulations for Monroe City Lake B Nr. Dam — or check the official Missouri fishing regulations.
All Lakes in Monroe County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Monroe City Lake B Nr. Dam | C | - | 44 µg/L |
| 2 | Mark Twain Lake | C | 3.8 ft | 36 µg/L |
| 3 | Mark Twain Lake | F | 2.5 ft | 80 µg/L |
Other Counties in Missouri
See how Monroe County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 15 states.
Where to stay near Monroe County
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Source: EPA National Aquatic Resource Surveys, 2026.