Thomas Hill Lake @ Hwy T
Macon County, WisconsinEutrophic
Thomas Hill Lake @ Hwy T is a productive, nutrient-rich eutrophic lake in Macon County, MO. Water quality is graded C based on 2 sampling years through 2025. Compared to the 3 other monitored lakes in Macon County, Thomas Hill Lake @ Hwy T ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2025-08-14. Grade methodology: LakeGrade methodology.
Swimming Safety
Swim with caution, moderate algae may be present
Water Quality Grade: C, Fair
No clarity data. Phosphorus level: 51 µg/L. Chlorophyll-a: 21.4 µg/L. Trophic State Index: 61.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 51 µg/L | C |
| Chlorophyll-a (Algae) | 21.4 µg/L | D |
| Trophic State Index (TSI) | 61 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Location
County Ranking
Ranked #2 of 4 lakes in Macon County
Cleaner Lakes Within 30 Miles
Thomas Hill Lake @ Hwy T holds Grade C. One nearby lake has a higher grade.
See full comparison →Nearby Lakes in Macon County
More Wisconsin Lake Rankings
Other Grade C Lakes in Wisconsin
Warren County · Clarity: 3.8 ft
Ralls County · Clarity: 3.7 ft
Warren County · Clarity: 3.3 ft
Platte County · Clarity: 4.7 ft
Barry County · Clarity: 5 ft
Phelps County · Clarity: 4.9 ft
Eutrophic Lakes in Wisconsin
EPA Impairment Status
Thomas Hill Lake @ Hwy T is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MO_7173.00 · Official waterbody report · Matched by proximity (1.42 km)
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-08-14
Monitoring stations: 1