Missouri vs Illinois, Lake Water Quality Comparison
A data-driven comparison of lake water quality between Missouri and Illinois, built from EPA Water Quality Portal monitoring data.
| Missouri | Illinois | |
|---|---|---|
| Total Lakes | 278 | 148 |
| Average Score | 1.81 | 0.99 |
| Oligotrophic (Cleanest) | 17 | 0 |
| Eutrophic (High Nutrient) | 99 | 35 |
| Lakes with Invasives | 13 | 7 |
| Improving Trend | 89 | 10 |
| Declining Trend | 92 | 7 |
Analysis
Missouri has 278 lakes with nutrient and algae readings, against 148 in Illinois. On average water quality, Missouri comes out ahead.Missouri counts 17 oligotrophic lakes, the clearest trophic class, against 0 in Illinois.
Long-term monitoring shows 89 improving and 92 declining lakes in Missouri, versus 10 improving and 7 declining in Illinois. Dataset coverage varies by state: Missouri has maximum-depth data for 0 lakes and documented fish species on 0, compared with 0 and 0 for Illinois. 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 Missouri or Illinois have cleaner lakes?
Missouri lakes average a composite water-quality score of 1.81; Illinois lakes average 0.99. Missouri has the better average water quality. Grades are computed from EPA Water Quality Portal clarity and nutrient measurements.
Which state has more measured lakes?
Missouri has 278 measured lakes while Illinois has 148. Counts reflect lakes with enough EPA Water Quality Portal monitoring data to reae, not the total number of lakes in each state.