Cleaner Lakes Than Corydon Reservoir
2 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Corydon Reservoir carries a Grade F (Very Poor) water quality score. Within 30 miles, 2 lakes hold a higher grade. Bob White Lake (Wayne County, Grade D, 4.2 mi away) is the closest meaningful upgrade.
2
DRathbun Lake
Appanoose County, Wisconsin · 23.5 mi from Corydon Reservoir
- +Higher grade (F → D)
- ++1.1 ft water clarity
How this list is built
Every lake on LakeQuality has a calculated grade from EPA Water Quality Portal samples — secchi depth, total phosphorus, and chlorophyll-a measured against Metropolitan Council thresholds. To suggest cleaner alternatives, we filter lakes within 30 miles to those with a strictly higher numeric score, then rank by grade improvement with a small proximity tiebreak. Cross-state and limited-data lakes are excluded so the list stays locally relevant.