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.
- Clarity
- 11 ft
- Max depth
- 123 ft
- Area
- 1,118 acres
- Trend
- ↑ Improving
- Public access
- Yes
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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
We grade a lake only when the monitoring record supports a letter: at least three phosphorus or chlorophyll-a samples in the last ten years, scored against EPA National Lakes Assessment thresholds for this lake’s ecoregion. For Cass Lake, 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. Sampling here has recorded water clarity, but not phosphorus and algae (chlorophyll-a).
Not Rated is not an F. It is EPA Integrated Reporting Category 3 — insufficient information. The water here may be excellent or poor; nobody has measured enough of it to say. 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.
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Swimming Safety
Not ratedLimited data
Not rated for swimming — there is not enough monitoring data to judge this lake
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. Trophic State Index: 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
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
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Planning a trip? Cabins and lodging at Cass Lake → · more Michigan lake trips
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) — there is not enough recent sampling to assign a letter.
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?
- Not rated for swimming — there is not enough monitoring data to judge this lake. Cass Lake is not rated for water quality — its monitoring record does not meet the evidence bar. Always check local health department advisories before swimming.
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
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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)
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