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 | 628 | 1,422 |
| Average Grade | B | C |
| Average Score | 2.77 | 2.46 |
| Grade A Lakes | 202 | 455 |
| Grade B Lakes | 220 | 370 |
| Grade C Lakes | 132 | 300 |
| Grade D Lakes | 52 | 183 |
| Grade F Lakes | 22 | 114 |
| Oligotrophic (Cleanest) | 183 | 260 |
| Eutrophic (High Nutrient) | 101 | 481 |
| Fish Species Documented | 99 | 9 |
| Lakes with Fish Data | 348 | 1,171 |
| Lakes with Invasives | 9 | 911 |
| Average Depth (ft) | - | 34 ft |
| Lakes with Depth Data | 0 | 1,193 |
| Improving Trend | 286 | 578 |
| Declining Trend | 80 | 341 |
Analysis
Michigan has 628 graded lakes averaging a B (score 2.77), while Wisconsin has 1,422 graded lakes averaging a C (score 2.46). On average water quality, Michigan comes out ahead.Michigan counts 202 Grade A lakes and 183 oligotrophic (clearest-class) lakes, against 455 and 260 for Wisconsin.
Long-term monitoring shows 286 improving and 80 declining lakes in Michigan, versus 578 improving and 341 declining in Wisconsin. Dataset coverage varies by state: Michigan has maximum-depth data for 0 lakes and documented fish species on 348, compared with 1,193 and 1,171 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 2.77) while Wisconsin averages C (score 2.46). 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 628 graded lakes while Wisconsin has 1,422. Counts reflect lakes with enough EPA Water Quality Portal monitoring data to grade, not the total number of lakes in each state.