Johnson County Lake Quality
Iowa, 3 lakes, average grade D (Poor)
Only 3 lakes in Johnson 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. On average, Johnson County lakes grade D, with phosphorus loading and reduced clarity showing up across most of the dataset.
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 Kent Park Lake (C); the most-stressed is Terry Trueblood Lake (F).
Quick Answers for Johnson County
Planning a trip? Check special fishing regulations for Kent Park Lake — or check the official Iowa fishing regulations.
All Lakes in Johnson County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Kent Park Lake | C | 4.8 ft | - |
| 2 | Lake Macbride | D | 2.9 ft | - |
| 3 | Terry Trueblood Lake | F | 1.1 ft | - |
Other Counties in Iowa
See how Johnson 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 Johnson County
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Source: EPA National Aquatic Resource Surveys, 2026.