1
CMormon Trail Lake
Adair County, Wisconsin · 16.5 mi from Green Valley Lake
- +Two grade letters higher (F → C)
- ++4.7 ft water clarity
Cleaner Lakes Than Green Valley Lake
3 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Green Valley Lake carries a Grade F (Very Poor) water quality score. Within 30 miles, 3 lakes hold a higher grade. Mormon Trail Lake (Adair County, Grade C, 16.5 mi away) is the closest meaningful upgrade.
2
DThree Mile Lake
Union County, Wisconsin · 9.1 mi from Green Valley Lake
- +Higher grade (F → D)
- ++1.2 ft water clarity
3
DNodaway Lake
Adair County, Wisconsin · 14.5 mi from Green Valley Lake
- +Higher grade (F → D)
- ++1.3 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.