Long Lake
Cass County, Michigan238 acresView mapDirections
EGLE publishes the water-quality measurements for Long Lake. Here is what has been measured.
- Impaired · Nutrients (phosphorus, nitrogen)
- 42 ft max depth
- Limited data
Long Lake in Cass County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 10.5 ft visibility. Maximum depth: 42 ft. Surface area: 238.3 acres.
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.
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. Methodology: how these readings are compared.
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 conditions
No readingLimited data
Nutrient and algae readings are 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.
Whether Long 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 Long Lake
These are the measurements EGLE publishes for Long 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 10.5 ft. TSI 43.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 10.5ft | 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 Long Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
42 ft
Surface area
238 acres
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Fish Species
Click a species to see every lake where it is documented.
Fishing Long Lake
Water Quality Trend: Improving
Based on 5 years of monitoring (2019–2023).
Water clarity
Improving5 years
Phosphorus
Worsening+1.4 µg/L/yr4 years
Chlorophyll-a
Improving-0.35 µg/L/yr3 years
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
Designated uses not supporting: Aquatic life.
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.
Nearby Lakes in Cass County
Frequently asked questions about Long Lake
Where is Long Lake?
- Long Lake is a lake in Cass County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Long Lake?
- Long Lake in Cass County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 10.5 ft visibility. Maximum depth: 42 ft. Surface area: 238.3 acres.
Is Long Lake safe to swim in?
- Nutrient and algae readings are 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)
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)