1
ADeep Portage Lake
Cass County, Minnesota · 1.9 mi from Big Portage (W Bay Lake
- +Higher grade (B → A)
- ++7.9 ft water clarity
- +Lower phosphorus (10 vs 20 µg/L)
Cleaner Lakes Than Big Portage (W Bay Lake
3 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Big Portage (W Bay Lake carries a Grade B (Good) water quality score. Within 30 miles, 3 lakes hold a higher grade. Deep Portage Lake (Cass County, Grade A, 1.9 mi away) is the closest meaningful upgrade.
2
ARainy Lake
Cass County, Minnesota · 1.1 mi from Big Portage (W Bay Lake
- +Higher grade (B → A)
- ++6.4 ft water clarity
- +Lower phosphorus (11.5 vs 20 µg/L)
3
AFive Point Lake
Cass County, Minnesota · 2 mi from Big Portage (W Bay Lake
- +Higher grade (B → A)
- ++5.3 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.