1
ASouth Twin Lake
Polk County, Wisconsin · 2.9 mi from Black Brook Flowage Lake
- +Higher grade (B → A)
- ++12.3 ft water clarity
- +Lower phosphorus (11.7 vs 46.6 µg/L)
Cleaner Lakes Than Black Brook Flowage Lake
4 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Black Brook Flowage Lake carries a Grade B (Good) water quality score. Within 30 miles, 4 lakes hold a higher grade. South Twin Lake (Polk County, Grade A, 2.9 mi away) is the closest meaningful upgrade.
2
AClear Lake
Polk County, Wisconsin · 5.2 mi from Black Brook Flowage Lake
- +Higher grade (B → A)
- ++30.4 ft water clarity
- +Lower phosphorus (13.9 vs 46.6 µg/L)
3
AKing Lake
Polk County, Wisconsin · 1.8 mi from Black Brook Flowage Lake
- +Higher grade (B → A)
- ++17.2 ft water clarity
- +Lower phosphorus (20.6 vs 46.6 µg/L)
4
ABear Trap Lake
Polk County, Wisconsin · 3.7 mi from Black Brook Flowage Lake
- +Higher grade (B → A)
- ++9 ft water clarity
- +Lower phosphorus (24.9 vs 46.6 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.