1
ADutch Hollow Lake
Sauk County, Wisconsin · 15 mi from Decorah Lake
- +Two grade letters higher (D → A)
- ++41.8 ft water clarity
- +Lower phosphorus (13.1 vs 116 µg/L)
Cleaner Lakes Than Decorah Lake
5 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Decorah Lake carries a Grade D (Poor) water quality score. Within 30 miles, 5 lakes hold a higher grade. Dutch Hollow Lake (Sauk County, Grade A, 15 mi away) is the closest meaningful upgrade.
2
AFawn Lake
Adams County, Wisconsin · 14.5 mi from Decorah Lake
- +Two grade letters higher (D → A)
- ++23.8 ft water clarity
- +Lower phosphorus (20.4 vs 116 µg/L)
3
BEaston Lake
Adams County, Wisconsin · 14 mi from Decorah Lake
- +Two grade letters higher (D → B)
- ++18.8 ft water clarity
- +Lower phosphorus (45.5 vs 116 µg/L)
4
BArkdale Lake
Adams County, Wisconsin · 18.5 mi from Decorah Lake
- +Two grade letters higher (D → B)
- ++7.4 ft water clarity
- +Lower phosphorus (21.8 vs 116 µg/L)
5
BFriendship Lake
Adams County, Wisconsin · 18.3 mi from Decorah Lake
- +Two grade letters higher (D → B)
- ++5.7 ft water clarity
- +Lower phosphorus (31 vs 116 µg/L)
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.