Hardin County Lake Quality
Iowa, 7 lakes, average grade F (Very Poor)
Hardin County has 7 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 average is F — the most-stressed bracket in our rubric. Most monitored lakes here show persistent nutrient loading and algal pressure.
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 Upper Pine Lake (F); the most-stressed is Upper Pine Lake (F).
Quick Answers for Hardin County
Planning a trip? Check special fishing regulations for Upper Pine Lake — or check the official Iowa fishing regulations.
All Lakes in Hardin County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Upper Pine Lake | F | 1.3 ft | - |
| 2 | Lower Pine Lake | F | 1.3 ft | - |
| 3 | Pine Lake South Beach | F | 1.4 ft | - |
| 4 | Lpinelk T Lake | F | 1.3 ft | - |
Other Counties in Iowa
See how Hardin 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 Hardin County
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Source: EPA National Aquatic Resource Surveys, 2026.