DeKalb County Lake Quality
Illinois, 1 lakes, average grade C (Fair)
Only 1 lakes in DeKalb 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 average is C — the middle of the rubric, with one or two lakes pulling the average up or down depending on year.
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 Shabbona Lake (C); the most-stressed is Shabbona Lake (C).
Quick Answers for DeKalb County
Planning a trip? Check special fishing regulations for Shabbona Lake — or check the official Illinois fishing regulations.
All Lakes in DeKalb County
| Rank | Lake | Grade | Clarity | Phosphorus |
|---|---|---|---|---|
| 1 | Shabbona Lake | C | 4.9 ft | 27.5 µg/L |
Other Counties in Illinois
See how DeKalb County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 15 states.
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Source: EPA National Aquatic Resource Surveys, 2026.