Cass Lake is a mesotrophic lake in Oakland County, Michigan. Water quality is graded B based on 1 sampling years through 2022. Water clarity is improving over recent sampling years. The lake supports 1 documented fish species including Lake herring. Public access is available with 1 public boat landing. Compared to the 44 other monitored lakes in Oakland County, Cass Lake ranks #22 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2022-09-08. Grade methodology: LakeGrade methodology.
Watch Cass Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 12 ft. Trophic State Index: 41.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 41 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Cass Lake
Compare lakeside cabins, hotels, and vacation rentals near Cass Lake in Oakland County, Michigan — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water.
Top-rated places to stay near Cass Lake
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a trip to Cass Lake?
Get lake water-quality report cards plus the best cabin & lodging deals near Cass Lake — straight to your inbox. No spam, unsubscribe anytime.
Planning a whole trip? See where to stay at Michigan’s top lakes →
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Cass Lake
Water Quality Trend: → Stable
Based on 3 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +2 m/yr | 3 |
| Chlorophyll-a | ↓ Declining | +3.25 µg/L/yr | 3 |
Recreation & Access
Location & Depth Map
Free interactive depth-contour map of Cass Lake, reaching a maximum surveyed depth of 123 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
County Ranking
Ranked #22 of 45 lakes in Oakland County
Nearby Lakes in Oakland County
Explore Cass Lake across LakeGrade
Fish species and top-graded lakes across Michigan
Fish species and best lakes in Oakland County
Species activity outlook by water temperature and season
Where to stay at Michigan's top lakes, each with its grade
Moderate nutrients, good water quality
Michigan's cleanest and most-polluted lakes, ranked
More Michigan Lake Rankings
Other Grade B Lakes in Michigan
Livingston County · Clarity: 12 ft
Genesee County · Clarity: 12 ft
Livingston County · Clarity: 12 ft
Genesee County · Clarity: 12 ft
Genesee County · Clarity: 10 ft
Genesee County · Clarity: 10 ft
Mesotrophic Lakes in Michigan
More records, surveys & data sources
EPA Impairment Status
Cass Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040900030108-03 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Cass Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Oakland Ps MS4-OaklandWaterford · 1.1 mi away · NPDES MI0060288Recent violation
Facilities permitted to discharge under the Clean Water Act within ~5 miles; proximity does not by itself mean a facility affects this lake. Source: EPA ECHO (ICIS-NPDES), as of 2026-07.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2022-09-08
Monitoring stations: 1