Sugarloaf Lake
Washtenaw County, Michigan280 acresView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
↑ up from B at the last regrade
- Oligotrophic
- #6 of 8 in the county
- 10 ft max depth
- Public access
- Limited data
Sugarloaf Lake in Washtenaw County, Michigan has a water quality grade of A (Excellent). Water clarity: 9.5 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 1.9 µg/L. Maximum depth: 10 ft. Surface area: 280 acres.
- Clarity
- 9.5 ft
- Max depth
- 10 ft
- Area
- 280 acres
- Type
- Oligotrophic
- Phosphorus
- 10 µg/L
- Chlorophyll-a
- 1.9 µg/L
- Trend
- ↑ Improving
- Public access
- Yes
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Free interactive depth-contour map of Sugarloaf Lake, reaching a maximum surveyed depth of 10 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
Sugarloaf Lake is a 280-acre cold, clear oligotrophic lake in Washtenaw County, Michigan with a maximum depth of 10 feet. Water quality is graded A based on 1 sampling years through 2023. Overall water quality is improving over recent sampling years. The lake supports 2 documented fish species including Northern pike and Spotted gar. Public access is available. Compared to the 7 other monitored lakes in Washtenaw County, Sugarloaf Lake ranks #6 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2023-09-24. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLimited data
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Moderate clarity, visible to about 9.5 ft. Phosphorus 10 µg/L. Chlorophyll-a 1.9 µg/L. TSI 40. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9.5 ft | Not graded |
| Phosphorus | 10 µg/L | Not graded |
| Chlorophyll-a (Algae) | 1.9 µg/L | Good |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 10 ft |
| Surface Area | 280 acres |
| Public Access | Yes |
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Sugarloaf Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +3.98 m/yr | 2 |
| Phosphorus | ↑ Improving | -6 µg/L/yr | 2 |
Reservoir Info (USACE NID)
Sugarloaf Lake is a man-made reservoir impounded by the Winnewana Dam (completed 1956), built primarily for recreation on the Tributary to Portage River; earth-type dam, 12 ft tall and 270 ft long.
- Surface area
- 280 ac
- Normal storage
- 1,000 ac-ft
- Max storage
- 1,560 ac-ft
- Drainage area
- 1.8 sq mi
- Hazard class
- Significant
- Owner
- MDNR Parks & Recreation
Source: USACE National Inventory of Dams, NID ID MI00327 · Operator website · Matched by proximity (0.8 km)
County Ranking
Ranked #6 of 8 lakes in Washtenaw County
Nearby Lakes in Washtenaw County
Frequently asked questions about Sugarloaf Lake
Where is Sugarloaf Lake?
- Sugarloaf Lake is a lake in Washtenaw County, Michigan. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Sugarloaf Lake?
- Sugarloaf Lake in Washtenaw County, Michigan has a water quality grade of A (Excellent). Water clarity: 9.5 ft visibility. Phosphorus: 10 µg/L. Chlorophyll-a (algae): 1.9 µg/L. Maximum depth: 10 ft. Surface area: 280 acres.
Is Sugarloaf Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
How deep is Sugarloaf Lake?
- Sugarloaf Lake has a maximum depth of 10 feet. The lake covers 280 acres.
What fish are in Sugarloaf Lake?
- Fish species found in Sugarloaf Lake include Northern pike, Spotted gar. Sugarloaf Lake is located in Washtenaw County, Michigan.
Explore Sugarloaf Lake across LakeQuality
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Washtenaw County
Species activity outlook by water temperature and season
Where to stay at Michigan's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
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Where this data comes from
26 measurements from 1 monitoring station, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS26 samples · 2022–2023
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.