1
BNorth Lemmon Lake
Adams County, Wisconsin · 25.3 mi from Castle Rock Dam Lake
- +Two grade letters higher (D → B)
- ++1.9 ft water clarity
Cleaner Lakes Than Castle Rock Dam Lake
3 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Castle Rock Dam Lake carries a Grade D (Poor) water quality score. Within 30 miles, 3 lakes hold a higher grade. North Lemmon Lake (Adams County, Grade B, 25.3 mi away) is the closest meaningful upgrade.
3
CIndian Creek Dam Lake
Hettinger County, Wisconsin · 10.9 mi from Castle Rock Dam Lake
- +Higher grade (D → C)
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.