1
BSand Lake
Marshall County, Wisconsin · 9.1 mi from Union Grove Lake
- +Two grade letters higher (F → B)
- ++4.8 ft water clarity
Cleaner Lakes Than Union Grove Lake
3 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Union Grove Lake carries a Grade F (Very Poor) water quality score. Within 30 miles, 3 lakes hold a higher grade. Sand Lake (Marshall County, Grade B, 9.1 mi away) is the closest meaningful upgrade.
2
CGreen Castle Lake
Marshall County, Wisconsin · 15.3 mi from Union Grove Lake
- +Two grade letters higher (F → C)
- ++3 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.