Iowa County Lake Quality
Wisconsin, 6 lakes, average grade D (Poor)
Iowa County has 6 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. On average, Iowa 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 Black Hawk Lake (B); the most-stressed is Ludden Lake (F).
Quick Answers for Iowa County
Planning a trip? Check special fishing regulations for Black Hawk Lake, whether the fish are safe to eat, and the best times to fish — or browse the full Wisconsin regulations index.
DNR Reports (7)
Wisconsin DNR Fisheries Survey resources for lakes in Iowa County. browse all reports →
- 2023Ludden Lake comprehensive survey 2023Comprehensive Survey · WI DNR · 2023 (PDF)
- 2022Cox Hollow Lake comprehensive survey 2022Comprehensive Survey · WI DNR · 2022 (PDF)
- 2021Blackhawk Lake comprehensive survey 2021Comprehensive Survey · WI DNR · 2021 (PDF)
- 2018Twin Valley Lake comprehensive survey 2018Comprehensive Survey · WI DNR · 2018 (PDF)
- 2017Blackhawk Lake comprehensive survey 2017Comprehensive Survey · WI DNR · 2017 (PDF)
- 2013Ludden Lake comprehensive survey 2013Comprehensive Survey · WI DNR · 2013 (PDF)
- 2011Lower Wisconsin River channel catfish 2011Fisheries Survey · WI DNR · 2011 (PDF)
All Lakes in Iowa County
| Rank | Lake | Grade | Clarity | Max Depth | Phosphorus |
|---|---|---|---|---|---|
| 1 | Black Hawk Lake | B | 5 ft | 42 ft | 19.9 µg/L |
| 2 | Goodwiler Lake | C | 4.7 ft | 5 ft | 29.7 µg/L |
| 3 | Kendal Lake | C | 6.9 ft | 17 ft | 32.7 µg/L |
| 4 | Helen Lake | C | 3.4 ft | 28 ft | 54.7 µg/L |
| 5 | Avoca Lake | D | 2 ft | 10 ft | 80.5 µg/L |
| 6 | Ludden Lake | F | 1.5 ft | 14 ft | 172 µg/L |
Source: EPA National Aquatic Resource Surveys, 2026.