Lake Isabella North Basin; Sherman Township
Lake Isabella North Basin; Sherman Township in Isabella County, Michigan has a water quality grade of B (Good). Water clarity: 6.5 ft visibility. Phosphorus: 15.5 µg/L. Surface area: 730 acres.
- Clarity
- 6.5 ft
- Mean depth
- ~12 ft est.
- Area
- 730 acres
- Type
- Mesotrophic
- Trend
- ↓ Declining
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Lake Isabella North Basin; Sherman Township is a 730-acre mesotrophic lake in Isabella County, Michigan with an estimated average depth of about 12 feet. Water quality is graded B based on 1 sampling years through 2019. Overall water quality is declining over recent sampling years. Compared to the 1 other monitored lakes in Isabella County, Lake Isabella North Basin; Sherman Township ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2019-09-18. Grade methodology: LakeQuality methodology.
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Swimming Safety
Grade onlyBacteria advisory
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Good for swimming, clear water with low algae levels
Compare the safest swimming lakes near Grand Rapids →
Get alerts for Lake Isabella North Basin; Sherman Township →
Water Quality Grade: B (Good)
Murky, only visible to about 6.5 ft. Phosphorus level: 15.5 µg/L. Trophic State Index: 47.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.5 ft | Not graded |
| Phosphorus | 15.5 µg/L | Good |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Lake Isabella North Basin; Sherman Township
Compare lakeside cabins, hotels, and vacation rentals near Lake Isabella North Basin; Sherman Township in Isabella 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.
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Lake Details
| Characteristic | Value |
|---|---|
| Average Depth | ~12 ft est. |
| Surface Area | 730 acres |
Depth marked “est.” is a modeled estimate from HydroLAKES, not a measured survey. Michigan has not published bathymetry for Lake Isabella North Basin; Sherman Township.
Lake Size & Watershed
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.
Fishing Lake Isabella North Basin; Sherman Township
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -1.1 m/yr | 4 |
| Phosphorus | ↓ Declining | +1 µg/L/yr | 4 |
Reservoir Info (USACE NID)
Lake Isabella North Basin; Sherman Township is a man-made reservoir impounded by the Lake Isabella Dam (completed 1967), built primarily for recreation on the Chippewa River; earth-type dam, 41 ft tall and 3,010 ft long.
- Surface area
- 730 ac
- Normal storage
- 5,760 ac-ft
- Max storage
- 13,500 ac-ft
- Drainage area
- 416 sq mi
- Hazard class
- High
- Owner
- Lake Isabella Corporation
Source: USACE National Inventory of Dams, NID ID MI00434 · Operator website · Matched by proximity (0.42 km)
EPA Impairment Status
Lake Isabella North Basin; Sherman Township is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MI040802020202-05 · Official waterbody report · Matched by proximity (1.93 km)
County Ranking
Ranked #2 of 2 lakes in Isabella County
Nearby Lakes With Higher Grades
Lake Isabella North Basin; Sherman Township holds Grade B. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
Nearby Lakes in Isabella County
Frequently asked questions about Lake Isabella North Basin; Sherman Township
Where is Lake Isabella North Basin; Sherman Township?
- Lake Isabella North Basin; Sherman Township is a lake in Isabella County, Michigan. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Lake Isabella North Basin; Sherman Township?
- Lake Isabella North Basin; Sherman Township in Isabella County, Michigan has a water quality grade of B (Good). Water clarity: 6.5 ft visibility. Phosphorus: 15.5 µg/L. Surface area: 730 acres.
Is Lake Isabella North Basin; Sherman Township safe to swim in?
- Good for swimming, clear water with low algae levels. Lake Isabella North Basin; Sherman Township has a water quality grade of B (Good). Always check local health department advisories before swimming.
How deep is Lake Isabella North Basin; Sherman Township?
- No published bathymetric survey covers Lake Isabella North Basin; Sherman Township, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 12 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 730 acres.
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Other Grade B Lakes in Michigan
Lake County · 10.5 ft
Kalkaska County · 22 ft
Muskegon County · 10 ft
Otsego County · 18 ft
Leelanau County · 11.2 ft
Allegan County · 13 ft
Mesotrophic Lakes in Michigan
Where this data comes from
83 measurements from 1 monitoring station, 2016–2019. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS83 samples · 2016–2019
Analytical methods
- Phosphorus by Colorimetry
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
Lake size & watershed from HydroLAKES (HydroSHEDS)