Back Bay Deep Lake is a mesotrophic lake in Chippewa County, Michigan. Water quality is graded B based on 3 sampling years through 2025. Overall water quality is declining over recent sampling years. Compared to the 17 other monitored lakes in Chippewa County, Back Bay Deep Lake ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2025-10-15. Grade methodology: LakeGrade methodology.
Watch Back Bay Deep Lake water quality
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Swimming Safety
Based on E. coli testing, Back Bay Deep Lake never exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 0% of 8 samples across 6 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Michigan’s current beach and health-department advisories before swimming.
Water Quality Grade: B, Good
Moderate clarity, visible to about 8.2 ft. Phosphorus level: 15 µg/L. Chlorophyll-a: 1.9 µg/L. Trophic State Index: 42.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 8.2 ft | C |
| Phosphorus | 15 µg/L | A |
| Chlorophyll-a (Algae) | 1.9 µg/L | A |
| Trophic State Index (TSI) | 42 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Back Bay Deep Lake
Compare lakeside cabins, hotels, and vacation rentals near Back Bay Deep Lake in Chippewa 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 Back Bay Deep Lake
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Fishing Back Bay Deep Lake
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.011 m/yr | 5 |
| Phosphorus | ↓ Declining | +1.61 µg/L/yr | 5 |
| Chlorophyll-a | ↓ Declining | +15.75 µg/L/yr | 3 |
Water Temperature
Back Bay Deep Lake averages about 63°F at the surface in summer, usually warmest in Aug (about 68°F) and coldest in Jan (about 32°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 325 field readings (2010–2025) via the EPA Water Quality Portal. See the full Back Bay Deep Lake water temperature breakdown →
Location
County Ranking
Ranked #9 of 18 lakes in Chippewa County
Cleaner Lakes Within 30 Miles
Back Bay Deep Lake holds Grade B. 2 nearby lakes hold higher grades.
- ASaint Mary'S River Offshore LakeChippewa County · 2.1 mi · Higher grade (B → A)
- ASaint Mary'S River Shore LakeChippewa County · 2.1 mi · Higher grade (B → A)
Nearby Lakes in Chippewa County
Explore Back Bay Deep Lake across LakeGrade
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Moderate nutrients, good water quality
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Other Grade B Lakes in Michigan
Mesotrophic Lakes in Michigan
More records, surveys & data sources
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
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2025-10-15
Monitoring stations: 1