Shag Lake
Marquette County, MichiganView mapDirections
EGLE publishes the water-quality measurements for Shag Lake. Here is what has been measured.
- Impaired · Mercury
- 34 ft max depth
- Public access
- Limited data
Shag Lake in Marquette County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 14.3 ft visibility. Phosphorus: 10 µg/L.
Shag Lake is a lake in Marquette County, Michigan with an estimated average depth of about 34 feet. Overall water quality is improving over recent sampling years. The lake supports 7 documented fish species including Blacknose shiner, Golden shiner, and Iowa darter. Public access is available.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2023-09-23. Methodology: how these readings are compared.
What Shag Lake is good for
From access and monitoring records, not editorial picks.
- Clear water14.3 ft of visibility
- Fishing7 species recorded
Swimming conditions
No readingLimited data
Nutrient and algae readings are not a swimming clearance. Shag Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
Whether Shag 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 Shag Lake
These are the measurements EGLE publishes for Shag 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 14.3 ft. Phosphorus 10 µg/L. TSI 38.
| Measure | Reading | Where it sits |
|---|---|---|
| Water clarity (Secchi depth) | 14.3ft | Measured, not scored How deep a black-and-white disk stays visible from the surface. Higher is clearer. |
| Total phosphorus | 10µg/L | Measured, not scored 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. | 38 | Oligotrophic OligotrophicMesotrophicEutrophicHypereutrophic |
Low nutrients, clear water. No reading is a swimming clearance.
Ask about Shag Lake
Answers come straight from the public measurements and survey records on this page.
Lake Details
Max depth
~34 ft est.
Public access
Yes
Listed by EGLE
Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. Michigan has not published bathymetry for Shag Lake.
Lake Size & Watershed
Watershed (drainage) area
3 sq mi
HydroLAKES / HydroSHEDS
Surface area
121 acres
HydroLAKES / HydroSHEDS
Shoreline
2.7 mi
HydroLAKES / HydroSHEDS
Elevation
1,171 ft
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.
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Stays near Shag Lake
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Fish Species
Click a species to see every lake where it is documented.
Fishing Shag Lake
Water quality readings over time
2 seasons of samples on record (2022–2023). Calling a direction takes at least 4 years of the same measurement.
Water clarity
Improving2 years
EPA Impairment Status
Shag Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 4A).
Causes of impairment
Designated uses not supporting: Fish consumption.
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040301100206-02 · Official waterbody report
Regulated Pollution Sources Nearby
1 EPA-permitted facility operate within about 5 miles of Shag Lake under Clean Water Act (NPDES) discharge permits.
- Joe & SonsGwinn · 3 mi away · NPDES MIG080309
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 Marquette County
Frequently asked questions about Shag Lake
Where is Shag Lake?
- Shag Lake is a lake in Marquette County, Michigan. Its water-quality measurements are published by EGLE and shown on this page as reported.
What is the water quality of Shag Lake?
- Shag Lake in Marquette County, Michigan has water-quality measurements published by EGLE, shown here as reported. Water clarity: 14.3 ft visibility. Phosphorus: 10 µg/L.
Is Shag Lake safe to swim in?
- Nutrient and algae readings are not a swimming clearance. Shag Lake is listed impaired under Clean Water Act §303(d) (IR 4A) for mercury. Check local advisories before you swim.
How deep is Shag Lake?
- No published bathymetric survey covers Shag Lake, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 34 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate.
What fish are in Shag Lake?
- Fish species found in Shag Lake include Blacknose shiner, Golden shiner, Iowa darter, Mimic shiner, Northern redbelly dace, White sucker, Yellow perch. Shag Lake is located in Marquette County, Michigan.
Can I fish at Shag Lake?
- Public access to Shag Lake is listed as yes on the lake record. 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 Shag Lake across LakeQuality
22 mi away · 100 ft
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Where this data comes from
16 measurements from 1 monitoring station, 2022–2023. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS16 samples · 2022–2023
Analytical methods
- Phosphorus by Colorimetry
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)
Lake size & watershed from HydroLAKES (HydroSHEDS)