Cass Lake
Oakland County, Michigan1,118 acresView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Impaired · Mercury
- 123 ft max depth
- Public access
- Limited data
Cass Lake in Oakland County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 11 ft visibility. Maximum depth: 123 ft. Surface area: 1118.3 acres.
- Clarity
- 11 ft
- Max depth
- 123 ft
- Area
- 1,118 acres
- Trend
- ↑ Improving
- Public access
- Yes
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
Prices for Sep 11–13, 4 adults. Change dates on the map below.
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? Cabins and lodging at Cass Lake → · more Michigan lake trips
Watch Cass Lake’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
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.
Why Cass Lake has no grade
Cass Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, Cass Lake is Not Rated — not an F. Its 11-foot median from 57 readings collected 2018–2022 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by EGLE and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
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. Grade methodology: LakeQuality methodology.
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 Safety
Not ratedLimited data
The letter is 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.
Water quality measurements for Cass Lake
These readings exist but are not enough for an A–F grade — see why.
Good clarity, visible to about 11 ft. TSI 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 11 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 123 ft |
| Surface Area | 1,118 acres |
| Public Access | Yes |
Recreation & Access
- Gerundegut BayPublic
Named access points in the USGS National Boat Ramps inventory, within about 3 miles. More lakes with boat ramps
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Cass Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.039 m/yr | 5 |
| Phosphorus | ↑ Improving | -0.91 µg/L/yr | 5 |
| Chlorophyll-a | → Stable | -0.07 µg/L/yr | 4 |
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
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.
Graded lakes near Cass Lake
Cass Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Oakland County
Frequently asked questions about Cass Lake
Where is Cass Lake?
- Cass Lake is a lake in Oakland County, Michigan. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for Cass Lake?
- Cass Lake in Oakland County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 11 ft visibility. Maximum depth: 123 ft. Surface area: 1118.3 acres.
Is Cass Lake safe to swim in?
- The letter is 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.
Explore Cass Lake across LakeQuality
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
Michigan's cleanest and most-polluted lakes, ranked
More Michigan Lake Rankings
Other Lakes in Michigan
Mesotrophic Lakes in Michigan
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)
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.
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