Michigan vs Wisconsin, Lake Water Quality Comparison
A data-driven comparison of lake water quality between Michigan and Wisconsin, built from EPA Water Quality Portal monitoring data.
| Michigan | Wisconsin | |
|---|---|---|
| Total Lakes | 646 | 1,428 |
| Average Grade | B | B |
| Average Score | 3.31 | 2.58 |
| Grade A Lakes | 119 | 36 |
| Grade B Lakes | 58 | 553 |
| Grade C Lakes | 26 | 134 |
| Grade D Lakes | 13 | 130 |
| Grade F Lakes | 0 | 0 |
| Oligotrophic (Cleanest) | 51 | 132 |
| Eutrophic (High Nutrient) | 36 | 275 |
| Fish Species Documented | 97 | 9 |
| Lakes with Fish Data | 340 | 1,177 |
| Lakes with Invasives | 9 | 914 |
| Average Depth (ft) | - | 34 ft |
| Lakes with Depth Data | 0 | 1,199 |
| Improving Trend | 337 | 532 |
| Declining Trend | 125 | 374 |
Analysis
Michigan has 646 graded lakes averaging a B (score 3.31), while Wisconsin has 1,428 graded lakes averaging a B (score 2.58). On average water quality, Michigan comes out ahead.Michigan counts 119 Grade A lakes and 51 oligotrophic (clearest-class) lakes, against 36 and 132 for Wisconsin.
Long-term monitoring shows 337 improving and 125 declining lakes in Michigan, versus 532 improving and 374 declining in Wisconsin. Dataset coverage varies by state: Michigan has maximum-depth data for 0 lakes and documented fish species on 340, compared with 1,199 and 1,177 for Wisconsin. Where a figure is zero, that state dataset has not yet been ingested — grades there rest on EPA clarity and nutrient measurements alone.
Frequently Asked Questions
Does Michigan or Wisconsin have cleaner lakes?
Michigan has an average lake grade of B (score 3.31) while Wisconsin averages B (score 2.58). Michigan has the better average water quality. Grades are computed from EPA Water Quality Portal clarity and nutrient measurements.
Which state has more graded lakes?
Michigan has 646 graded lakes while Wisconsin has 1,428. Counts reflect lakes with enough EPA Water Quality Portal monitoring data to grade, not the total number of lakes in each state.