St. Francois County Lake Quality
Missouri, 10 lakes, average grade B (Good)
St. Francois County holds 10 monitored lakes. With a sample that small the county-level summary describes those specific waters, not necessarily every water body in the county. 4 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. With an average grade of B, St. Francois County sits comfortably above the Missouri median.
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. Lake Capri (A) is the cleanest in the county.
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Quick Answers for St. Francois County
Planning a trip? Check special fishing regulations for Lake Capri — or check the official Missouri fishing regulations.
All Lakes in St. Francois County
10 lakes · 4 graded, 6 not rated4 graded lakes · 6 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | ALake CapriSt. Francois | A | 16.3 ft | 5.7 µg/L | 0.9 µg/L | No recent samples | Not recorded |
| 2 | ALake Marseilles-Terre du Lac LakesSt. Francois | A | 14.1 ft | 7.4 µg/L | 2.4 µg/L | No recent samples | Not recorded |
| 3 | ATimberline LakesSt. Francois | A | 14.3 ft | 5.5 µg/L | 1.6 µg/L | No recent samples | Not recorded |
| 4 | FHemitite LakeSt. Francois | F | 1.1 ft | 186.9 µg/L | 91.9 µg/L | No recent samples | ✓ Public |
| NREugene D Nims LakeSt. Francois | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRDeer Run LakeSt. Francois | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLake PrimroseSt. Francois | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRIron Mountain LakeSt. Francois | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRPilot Knob LakeSt. Francois | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded | |
| NRLac CarmelSt. Francois | NR | No recent samples | No recent samples | No recent samples | No recent samples | Not recorded |
NR = not rated: there is not enough recent sampling to support a letter. That is EPA Integrated Reporting Category 3 (insufficient information), not a failing grade. How grading works.
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Other Counties in Missouri
See how St. Francois County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all United States (49 states), Canada (Ontario, Québec, Nova Scotia, British Columbia and Newfoundland and Labrador), and 38 other country hubs..
Source: EPA National Aquatic Resource Surveys, 2026.