Linn County Lake Quality
Missouri, 4 lakes, average grade C (Fair)
Only 4 lakes in Linn 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. Linn County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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. Brookfield Lake (B) is the cleanest in the county.
Quick Answers for Linn County
Planning a trip? Check special fishing regulations for Brookfield Lake — or check the official Missouri fishing regulations.
All Lakes in Linn County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Brookfield Lake | B | 4.4 ft | 19.7 µg/L |
| 2 | Jo Shelby Lake | C | - | 48 µg/L |
| 3 | Pershing State Park Lake | D | - | 75 µg/L |
| 4 | Marceline Lake | F | 1.9 ft | 110.9 µg/L |
Other Counties in Missouri
See how Linn 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 Linn County
Top-rated places to stay near Linn County
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Linn County?
Get lake water-quality report cards plus the best cabin & lodging deals near Linn County — straight to your inbox. No spam, unsubscribe anytime.
Source: EPA National Aquatic Resource Surveys, 2026.