Pennington County Lake Quality
South Dakota, 1 lakes, average grade A (Excellent)
Pennington County has 1 graded 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. The county's average grade is A — among the cleanest in South Dakota. 1 lakes pull an A on their own, and almost none fall into the D or F brackets.
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 Canyon Lake (A); the most-stressed is Canyon Lake (A).
Quick Answers for Pennington County
Planning a trip? Check special fishing regulations for Canyon Lake — or check the official South Dakota fishing regulations.
All Lakes in Pennington County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Canyon Lake | A | - | - |
Other Counties in South Dakota
See how Pennington 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 Pennington County
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Source: EPA National Aquatic Resource Surveys, 2026.