1
ACattails 2 Lake
Jefferson County, Wisconsin · 13.8 mi from Fon-du-Lac Reservoir
- +Two grade letters higher (F → A)
- +Lower phosphorus (24 vs 81 µg/L)
Cleaner Lakes Than Fon-du-Lac Reservoir
5 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Fon-du-Lac Reservoir carries a Grade F (Very Poor) water quality score. Within 30 miles, 5 lakes hold a higher grade. Cattails 2 Lake (Jefferson County, Grade A, 13.8 mi away) is the closest meaningful upgrade.
2
BCattails 1 Lake
Jefferson County, Wisconsin · 14 mi from Fon-du-Lac Reservoir
- +Two grade letters higher (F → B)
- ++5 ft water clarity
- +Lower phosphorus (16 vs 81 µg/L)
3
CLake Tishomingo Nr. Dam
Jefferson County, Wisconsin · 13.9 mi from Fon-du-Lac Reservoir
- +Two grade letters higher (F → C)
- ++4.1 ft water clarity
- +Lower phosphorus (23.5 vs 81 µg/L)
4
DBoathouse Lake
St. Louis city County, Wisconsin · 12.1 mi from Fon-du-Lac Reservoir
- +Higher grade (F → D)
- +Lower phosphorus (59.8 vs 81 µg/L)
5
DSimpson Park Lake
St. Louis County, Wisconsin · 4.6 mi from Fon-du-Lac Reservoir
- +Higher grade (F → D)
- ++1.2 ft water clarity
- +Lower phosphorus (36 vs 81 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.