1
ALong Lake
Kandiyohi County, Minnesota · 7.6 mi from Koronis Lake
- +Two grade letters higher (C → A)
- ++4.5 ft water clarity
- +Lower phosphorus (13 vs 26 µg/L)
Cleaner Lakes Than Koronis Lake
4 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Koronis Lake carries a Grade C (Fair) water quality score. Within 30 miles, 4 lakes hold a higher grade. Long Lake (Kandiyohi County, Grade A, 7.6 mi away) is the closest meaningful upgrade.
2
BPirz Lake
Stearns County, Minnesota · 6.3 mi from Koronis Lake
- +Higher grade (C → B)
- ++5.2 ft water clarity
3
BCalhoun Lake
Kandiyohi County, Minnesota · 7.7 mi from Koronis Lake
- +Higher grade (C → B)
- ++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.