Lake Iowa
Iowa County, WisconsinEutrophic
Lake Iowa is a 92-acre productive, nutrient-rich eutrophic lake in Iowa County, IA. Water quality is graded F based on 2 sampling years through 2024. Compared to the 6 other monitored lakes in Iowa County, Lake Iowa ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2024-10-01. Grade methodology: LakeGrade methodology.
Swimming Safety
Avoid swimming, very poor water quality, potential algae toxins
Water Quality Grade: F, Very Poor
Very murky, less than 1.9 ft of visibility. Chlorophyll-a: 53.8 µg/L. Trophic State Index: 69.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 1.9 ft | F |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 53.8 µg/L | F |
| Trophic State Index (TSI) | 69 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 92 acres |
Location
County Ranking
Ranked #5 of 7 lakes in Iowa County
Cleaner Lakes Within 30 Miles
Lake Iowa holds Grade F. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Iowa County
More Wisconsin Lake Rankings
Other Grade F Lakes in Wisconsin
Eutrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Lake Iowa is a man-made reservoir impounded by the Lake Iowa Dam (completed 1962), built primarily for recreation on the PIG CREEK; earth-type dam, 40 ft tall and 893 ft long.
- Surface area
- 92 ac
- Normal storage
- 1,110 ac-ft
- Max storage
- 1,950 ac-ft
- Drainage area
- 2.17 sq mi
- Hazard class
- Significant
- Owner
- Iowa County Conservation Board
Source: USACE National Inventory of Dams, NID ID IA00520 · Operator website
EPA Impairment Status
Lake Iowa is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit IA 02-IOW-677 · Official waterbody report
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2024-10-01
Monitoring stations: 1