Iowa County Lake Quality
Wisconsin, 6 lakes, average grade C (Fair)
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. Iowa County averages to a C. The distribution behind that average matters more than the letter: a few stressed lakes versus many decent ones can produce the same average as the inverse.
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 (D).
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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.
Fishing in Iowa County
DNR Reports (7)
Wisconsin DNR Fisheries Survey resources for lakes in Iowa County. browse all reports →
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- 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
6 lakes6 graded lakes
| # | Lake | Grade | Clarity | Phosphorus | Algae | Trophic | Max Depth | Access |
|---|---|---|---|---|---|---|---|---|
| 1 | BBlack Hawk LakeIowa | B | 5 ft | 19.9 µg/L | No recent samples | No recent samples | 42 ft | ✓ Public |
| 2 | CGoodwiler LakeIowa | C | 4.7 ft | 29.7 µg/L | No recent samples | No recent samples | 5 ft | ✓ Public |
| 3 | CKendal LakeIowa | C | 6.9 ft | 32.7 µg/L | No recent samples | No recent samples | 17 ft | ✓ Public |
| 4 | DLudden LakeIowa | D | 1.5 ft | 172 µg/L | No recent samples | No recent samples | 14 ft | ✓ Public |
| 5 | DHelen LakeIowa | D | 3.4 ft | 54.7 µg/L | No recent samples | No recent samples | 28 ft | ✓ Public |
| 6 | DAvoca LakeIowa | D | 2 ft | 80.5 µg/L | No recent samples | No recent samples | 10 ft | ✓ Public |
Lake Match
Which lake suits how you actually use one?
Six questions — swimming, fishing, quiet, cabins, drive time — and a shortlist of graded lakes that fit, with the water quality behind each one.
Other Counties in Wisconsin
See how Iowa County stacks up in the national county water-quality rankings, or browse the full directory of graded lakes across all 39 states and 2 Canadian provinces.
Source: EPA National Aquatic Resource Surveys, 2026.