Long Lake
Cass County, Michigan238 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 · Nutrients (phosphorus, nitrogen)
- 42 ft max depth
- Limited data
Long Lake in Cass County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Maximum depth: 42 ft. Surface area: 238.3 acres.
- Clarity
- 10.5 ft
- Max depth
- 42 ft
- Area
- 238 acres
- Trend
- ↑ Improving
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Watch Long Lake’s letter
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Free interactive depth-contour map of Long Lake, reaching a maximum surveyed depth of 42 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
Why Long Lake has no grade
Long 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, Long Lake is Not Rated — not an F. Its 10.5-foot median from 52 readings collected 2019–2022 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.
Long Lake is a 238-acre lake in Cass County, Michigan with a maximum depth of 42 feet. Overall water quality is improving over recent sampling years. The lake supports 25 documented fish species including Blacknose shiner, Blackside darter, and Blackstripe topminnow.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2022-09-16. Grade methodology: LakeQuality methodology.
What Long Lake is good for
From access and monitoring records, not editorial picks.
- Clear water10.5 ft of visibility
- Fishing25 species recorded
- Deep water42 ft surveyed max depth
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Long Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
Water quality measurements for Long Lake
These readings exist but are not enough for an A–F grade — see why.
Good clarity, visible to about 10.5 ft. TSI 43.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 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 | 42 ft |
| Surface Area | 238 acres |
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long Lake
Water Quality Trend: ↑ Improving
Based on 5 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.176 m/yr | 5 |
| Phosphorus | ↓ Declining | +1.4 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -0.35 µg/L/yr | 3 |
EPA Impairment Status
Long Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MI040500011303-06 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Long Lake under Clean Water Act (NPDES) discharge permits.
- Porter Twp WwtpWhite Pigeon · 3.6 mi away · NPDES MI0057602
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 Long Lake
Long Lake has no grade, but these lakes within a short drive do.
Nearby Lakes in Cass County
Frequently asked questions about Long Lake
Where is Long Lake?
- Long Lake is a lake in Cass 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 Long Lake?
- Long Lake in Cass County, Michigan is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 10.5 ft visibility. Maximum depth: 42 ft. Surface area: 238.3 acres.
Is Long Lake safe to swim in?
- The letter is not a swimming clearance. Long Lake is listed impaired under Clean Water Act §303(d) (IR 5) for nutrients (phosphorus, nitrogen), oxygen depletion (low DO). Check local advisories before you swim.
How deep is Long Lake?
- Long Lake has a maximum depth of 42 feet. The lake covers 238.3 acres.
What fish are in Long Lake?
- Fish species found in Long Lake include Blacknose shiner, Blackside darter, Blackstripe topminnow, Bluegill, Bluntnose minnow, Brook silverside, Central stoneroller, Creek chub, Golden redhorse, Grass pickerel, Green sunfish, Hornyhead chub, Iowa darter, Johnny darter, Lake herring, Largemouth bass, Longnose gar, Mimic shiner, Northern logperch, Northern longear sunfish, Sand shiner, Smallmouth bass, Striped shiner, Western banded killifish, Yellow perch. Long Lake is located in Cass County, Michigan.
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Where this data comes from
52 measurements from 1 monitoring station, 2019–2022. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- North American Lake Management Society
NALMS52 samples · 2019–2022
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)