Iowa vs Minnesota, Lake Water Quality Comparison
A data-driven comparison of lake water quality between Iowa and Minnesota, built from EPA Water Quality Portal monitoring data.
| Iowa | Minnesota | |
|---|---|---|
| Total Lakes | 170 | 2,403 |
| Average Grade | D | C |
| Average Score | 0.58 | 2.22 |
| Grade A Lakes | 4 | 639 |
| Grade B Lakes | 8 | 582 |
| Grade C Lakes | 18 | 482 |
| Grade D Lakes | 41 | 391 |
| Grade F Lakes | 99 | 309 |
| Oligotrophic (Cleanest) | 1 | 446 |
| Eutrophic (High Nutrient) | 110 | 849 |
| Fish Species Documented | 0 | 72 |
| Lakes with Fish Data | 0 | 1,643 |
| Lakes with Invasives | 3 | 809 |
| Average Depth (ft) | - | 44 ft |
| Lakes with Depth Data | 0 | 1,862 |
| Improving Trend | 67 | 668 |
| Declining Trend | 51 | 725 |
| Ice Data Available | 0 | 1,071 |
Analysis
Iowa has 170 graded lakes averaging a D (score 0.58), while Minnesota has 2,403 graded lakes averaging a C (score 2.22). On average water quality, Minnesota comes out ahead.Iowa counts 4 Grade A lakes and 1 oligotrophic (clearest-class) lakes, against 639 and 446 for Minnesota.
Long-term monitoring shows 67 improving and 51 declining lakes in Iowa, versus 668 improving and 725 declining in Minnesota. Dataset coverage varies by state: Iowa has maximum-depth data for 0 lakes and documented fish species on 0, compared with 1,862 and 1,643 for Minnesota. 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 Iowa or Minnesota have cleaner lakes?
Iowa has an average lake grade of D (score 0.58) while Minnesota averages C (score 2.22). Minnesota has the better average water quality. Grades are computed from EPA Water Quality Portal clarity and nutrient measurements.
Which state has more graded lakes?
Iowa has 170 graded lakes while Minnesota has 2,403. Counts reflect lakes with enough EPA Water Quality Portal monitoring data to grade, not the total number of lakes in each state.