Mary Lake
Dickinson County, WisconsinLimited DataOligotrophic
Mary Lake is a 230-acre cold, clear oligotrophic lake in Dickinson County, MI. Water quality is graded B based on 1 sampling years through 2022. The lake supports 1 documented fish species including Lake herring. Compared to the 5 other monitored lakes in Dickinson County, Mary Lake ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2022-09-05. Grade methodology: LakeGrade methodology.
Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 13.8 ft. Trophic State Index: 39.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 13.8 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 39 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Lake Details
| Characteristic | Value |
|---|---|
| Surface Area | 230 acres |
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Mary Lake (14-day solunar calendar)
→ Is it safe to eat fish from Mary Lake? (mercury & PFAS guide)
→ Mary Lake fishing regulations (limits, seasons, special rules)
Location
County Ranking
Ranked #5 of 6 lakes in Dickinson County
Nearby Lakes in Dickinson County
More Wisconsin Lake Rankings
Other Grade B Lakes in Wisconsin
Lapeer County · Clarity: 9.5 ft
Livingston County · Clarity: 13 ft
Manistee County · Clarity: 11 ft
Lake County · Clarity: 14 ft
Cass County · Clarity: 10.5 ft
Genesee County · Clarity: 10 ft
Oligotrophic Lakes in Wisconsin
Reservoir Info (USACE NID)
Mary Lake is a man-made reservoir impounded by the Mary Lake Dam, built primarily for other on the Hamilton Creek; concrete-type dam, 7 ft tall and 237 ft long.
- Surface area
- 230 ac
- Normal storage
- 350 ac-ft
- Max storage
- 764 ac-ft
- Drainage area
- 15.1 sq mi
- Hazard class
- Low
- Owner
- Waucedah Township
Source: USACE National Inventory of Dams, NID ID MI01247 · Operator website
EPA Impairment Status
Mary Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040301080407-01 · Official waterbody report · Matched by proximity (2.58 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: 2022-09-05
Monitoring stations: 1