Cass Lake
Oakland County, Michigan1,118 acresView mapDirections
EGLE publishes the water-quality measurements for Cass Lake. Here is what has been measured.
- Impaired · Mercury
- 123 ft max depth
- Public access
- Limited data
Cass Lake in Oakland County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 11 ft visibility. Maximum depth: 123 ft. Surface area: 1118.3 acres.
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.
Cass Lake is a 1,118-acre lake in Oakland County, Michigan with a maximum depth of 123 feet. Overall water quality 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.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-08. Methodology: how these readings are compared.
Cass Lake covers about 1,100 acres in Oakland County. It has one public boat landing. For a place on the water, look through cabin and lake-house rentals near Cass Lake on Vrbo. For a hotel or motel room, Booking.com and Expedia both search around the lake.
What Cass Lake is good for
From access and monitoring records, not editorial picks.
- Clear water11 ft of visibility
- Boat launch1 documented ramp
- Deep water123 ft surveyed max depth
- Big water1,118 acres
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Cass Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pFAS, pCBs. Check local advisories before you swim.
Whether Cass Lake is safe to swim in today is a call for the Michigan Department of Environment, Great Lakes, and Energy (EGLE) and the county health department, who post current advisories. LakeQuality does not issue swimming clearances.
Water quality measurements for Cass Lake
These are the measurements EGLE publishes for Cass Lake, shown as reported. The condition class beside each reading is the EPA National Lakes Assessment class for this lake’s ecoregion.
Good clarity, visible to about 11 ft. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 11ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | No reading The nutrient that most limits algae growth in freshwater. More phosphorus, more algae potential. | |
| Chlorophyll-a (algae) | No reading The green pigment in algae — a direct measure of how much algae is in the water. | |
| Trophic state (TSI)Carlson's 0–100 index of how much algae a lake can support, from clarity, phosphorus and chlorophyll-a. | 43 | Mesotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Moderate nutrients, good water quality
Ask about Cass Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
123 ft
Surface area
1,118 acres
Public access
Yes
Listed by EGLE
Recreation & Access
- Gerundegut BayPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Stays via Stay22
Stays 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
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Fish Species
Click a species to see every lake where it is documented.
Fishing Cass Lake
Water Quality Trend: Improving
Based on 5 years of monitoring (2018–2023).
Water clarity
Improving5 years
Phosphorus
Improving-0.91 µg/L/yr5 years
Chlorophyll-a
Stable-0.07 µg/L/yr4 years
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
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040900030108-03 · Official waterbody report
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.
Nearby Lakes in Oakland County
Frequently asked questions about Cass Lake
Where is Cass Lake?
- Cass Lake is a lake in Oakland County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Cass Lake?
- Cass Lake in Oakland County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 11 ft visibility. Maximum depth: 123 ft. Surface area: 1118.3 acres.
Is Cass Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Cass Lake is listed impaired under Clean Water Act §303(d) (IR 5) for mercury, pFAS, pCBs. Check local advisories before you swim.
How deep is Cass Lake?
- Cass Lake has a maximum depth of 123 feet. The lake covers 1118.3 acres.
What fish are in Cass Lake?
- Fish species found in Cass Lake include Lake herring. Cass Lake is located in Oakland County, Michigan.
Are there boat ramps on Cass Lake?
- Cass Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Named access points include Gerundegut Bay. Public access is listed as yes.
Can I fish at Cass Lake?
- Cass Lake has 1 documented boat landing in the USGS National Boat Ramps inventory. Seasons, size and bag limits, and whether you need a license are set by Michigan's fish and wildlife agency, so check its current regulations before you go.
Explore Cass Lake across LakeQuality
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Where this data comes from
57 measurements from 1 monitoring station, 2018–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS57 samples · 2018–2022
Monitoring station identifiers (1)
EPA condition classes from the National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See where the data comes from and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Named boat-access points from the USGS National Boat Ramps inventory