1
DMadison Lake
Blue Earth County, Minnesota · 1.8 mi from Duck Lake
- +Higher grade (F → D)
- +Lower phosphorus (75 vs 105 µg/L)
Cleaner Lakes Than Duck Lake
2 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Duck Lake carries a Grade F (Very Poor) water quality score. Within 30 miles, 2 lakes hold a higher grade. Madison Lake (Blue Earth County, Grade D, 1.8 mi away) is the closest meaningful upgrade.
2
FWashington Lake
Le Sueur County, Minnesota · 3.6 mi from Duck Lake
- +Higher overall water quality score
- ++1.7 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.