Sumner County Lake Quality
Kansas, 2 lakes, average grade D (Poor)
Only 2 lakes in Sumner 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. The county-wide average grade is D — water quality issues are persistent across most of the monitored basins. 0 lakes fall into the F bracket outright.
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. Wellington New City Lake (D) is the cleanest in the county.
Quick Answers for Sumner County
Planning a trip? Check special fishing regulations for Wellington New City Lake — or check the official Kansas fishing regulations.
All Lakes in Sumner County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Wellington New City Lake | D | 1.9 ft | 70.5 µg/L |
| 2 | Slate Creek Wildlife Area Wetland Lake | D | 0.7 ft | 315 µg/L |
Other Counties in Kansas
See how Sumner 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 Sumner County
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Source: EPA National Aquatic Resource Surveys, 2026.