Brown County Lake Quality
Kansas, 5 lakes, average grade D (Nutrient-rich)
Brown County has 5 monitored lakes — a thin enough sample that one or two stressed lakes can move the county average noticeably. Use the per-lake pages below for what actually matters. 2 of those lakes carry an A–F grade. The county-level summary describes that subset, not every water body listed. On average, Brown 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. Mission Lake (C) is the cleanest in the county.
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Quick Answers for Brown County
Planning a trip? Check special fishing regulations for Mission Lake — or check the official Kansas fishing regulations.
All Lakes in Brown County
5 lakes · 2 graded, 3 not rated2 graded lakes · 3 not rated, hidden
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Access |
|---|---|---|---|---|---|---|---|
| 1 | CMission LakeBrown | C | 1 ft | 170 µg/L | 9.3 µg/L | No recent samples | Not recorded |
| 2 | FHiawatha City LakeBrown | F | 2.1 ft | 135 µg/L | 93 µg/L | No recent samples | Not recorded |
| NRBrown Co State Fishing LakeBrown | NR | 1.3 ft | 88 µg/L | 64.5 µg/L | No recent samples | Not recorded | |
| NRPony Creek LakeBrown | NR | 2.2 ft | 83 µg/L | 62 µg/L | No recent samples | Not recorded | |
| NRLittle LakeBrown | NR | No recent samples | 250 µg/L | 155 µg/L | 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 Kansas
See how Brown 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.