Illinois vs Indiana, Lake Water Quality Comparison
A data-driven comparison of lake water quality between Illinois and Indiana, built from EPA Water Quality Portal monitoring data.
| Illinois | Indiana | |
|---|---|---|
| Total Lakes | 148 | 22 |
| Average Score | 0.99 | 2.5 |
| Oligotrophic (Cleanest) | 0 | 1 |
| Eutrophic (High Nutrient) | 35 | 0 |
| Lakes with Invasives | 7 | 4 |
| Improving Trend | 10 | 4 |
| Declining Trend | 7 | 8 |
Analysis
Illinois has 148 lakes with nutrient and algae readings, against 22 in Indiana. On average water quality, Indiana comes out ahead.Illinois counts 0 oligotrophic lakes, the clearest trophic class, against 1 in Indiana.
Long-term monitoring shows 10 improving and 7 declining lakes in Illinois, versus 4 improving and 8 declining in Indiana. Dataset coverage varies by state: Illinois has maximum-depth data for 0 lakes and documented fish species on 0, compared with 0 and 0 for Indiana. 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 Illinois or Indiana have cleaner lakes?
Illinois lakes average a composite water-quality score of 0.99; Indiana lakes average 2.5. Indiana has the better average water quality. Grades are computed from EPA Water Quality Portal clarity and nutrient measurements.
Which state has more measured lakes?
Illinois has 148 measured lakes while Indiana has 22. Counts reflect lakes with enough EPA Water Quality Portal monitoring data to reae, not the total number of lakes in each state.