1
BLake Nehai Tonkayea
Chariton County, Wisconsin · 13.3 mi from Thomas Hill Res. Nr. Dam Lake
- +Two grade letters higher (D → B)
- ++5.7 ft water clarity
- +Lower phosphorus (10 vs 61 µg/L)
Cleaner Lakes Than Thomas Hill Res. Nr. Dam Lake
5 higher-graded lakes within 30 miles, ranked by grade improvement and proximity.
Thomas Hill Res. Nr. Dam Lake carries a Grade D (Poor) water quality score. Within 30 miles, 5 lakes hold a higher grade. Lake Nehai Tonkayea (Chariton County, Grade B, 13.3 mi away) is the closest meaningful upgrade.
2
COld Reservoir
Randolph County, Wisconsin · 13.6 mi from Thomas Hill Res. Nr. Dam Lake
- +Higher grade (D → C)
- ++1.3 ft water clarity
- +Lower phosphorus (33 vs 61 µg/L)
3
CRothwell Lake
Randolph County, Wisconsin · 13.6 mi from Thomas Hill Res. Nr. Dam Lake
- +Higher grade (D → C)
- ++1.3 ft water clarity
- +Lower phosphorus (32 vs 61 µg/L)
4
CThomas Hill Lake @ Hwy T
Macon County, Wisconsin · 4.9 mi from Thomas Hill Res. Nr. Dam Lake
- +Higher grade (D → C)
- +Lower phosphorus (51 vs 61 µg/L)
5
DSugar Creek Lake
Randolph County, Wisconsin · 11.2 mi from Thomas Hill Res. Nr. Dam Lake
- +Higher overall water quality score
- +Lower phosphorus (50.5 vs 61 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.