Shag Lake is a cold, clear oligotrophic lake in Marquette County, Michigan. Water quality is graded A based on 1 sampling years through 2023. 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 with 2 public boat landings. Compared to the 9 other monitored lakes in Marquette County, Shag Lake ranks #1 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2023-05-31. Grade methodology: LakeGrade methodology.
Watch Shag Lake water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 15.3 ft down. Trophic State Index: 38.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 15.3 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 38 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Shag Lake
Compare lakeside cabins, hotels, and vacation rentals near Shag Lake in Marquette 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 Shag Lake
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 to Shag Lake?
Get lake water-quality report cards plus the best cabin & lodging deals near Shag Lake — straight to your inbox. No spam, unsubscribe anytime.
Planning a whole trip? See where to stay at Michigan’s top lakes →
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Shag Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +3.59 m/yr | 2 |
Recreation & Access
Location & Depth Map
Free interactive depth-contour map of Shag Lake, reaching a maximum surveyed depth of 30 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
County Ranking
Ranked #1 of 10 lakes in Marquette County
Nearby Lakes in Marquette County
Explore Shag Lake across LakeGrade
Fish species and top-graded lakes across Michigan
Fish species and best lakes in Marquette County
Species activity outlook by water temperature and season
Top lakes and where to stay in the Upper Peninsula area
Where to stay at Michigan's top lakes, each with its grade
Low nutrients, clear water, excellent for swimming
Michigan's cleanest and most-polluted lakes, ranked
More Michigan Lake Rankings
Other Grade A Lakes in Michigan
Iron County · Clarity: 18 ft
Iron County · Clarity: 17 ft
Iron County · Clarity: 19.5 ft
Iron County · Clarity: 18 ft
Alger County · Clarity: 15 ft
Alger County · Clarity: 15 ft
Oligotrophic Lakes in Michigan
More records, surveys & data sources
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
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040301100206-02 · Official waterbody report
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2023-05-31
Monitoring stations: 1