Sioux County Lake Quality
Nebraska, 1 lakes, average grade B (Good)
Only 1 lakes in Sioux 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. With an average grade of B, Sioux County sits comfortably above the {{stateName}} median.
The county's lakes lean shallow, which makes the grades sensitive to wind, sediment-resuspension, and any nutrient inputs from the watershed. The cleanest lake on the books is Lake Carter P Johnson (B); the most-stressed is Lake Carter P Johnson (B).
Quick Answers for Sioux County
Planning a trip? Check special fishing regulations for Lake Carter P Johnson — or check the official Nebraska fishing regulations.
All Lakes in Sioux County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Lake Carter P Johnson | B | 8.3 ft | - |
Other Counties in Nebraska
See how Sioux County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 34 states.
Where to stay near Sioux County
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Source: EPA National Aquatic Resource Surveys, 2026.