Diamond Lake East Basin; Penn Township
Diamond Lake East Basin; Penn Township in Cass County, Michigan has a water quality grade of A (Excellent). Water clarity: 12.3 ft visibility. Phosphorus: 6 µg/L. Chlorophyll-a (algae): 2 µg/L. Maximum depth: 64 ft. Surface area: 1039.8 acres.
- Clarity
- 12.3 ft
- Max depth
- 64 ft
- Area
- 1,040 acres
- Type
- Oligotrophic
- Trend
- ↓ Declining
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Diamond Lake East Basin; Penn Township is a 1,040-acre cold, clear oligotrophic lake in Cass County, Michigan with a maximum depth of 64 feet. Water quality is graded A based on 2 sampling years through 2019. Overall water quality is declining over recent sampling years. Compared to the 9 other monitored lakes in Cass County, Diamond Lake East Basin; Penn Township ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2019-09-19. Grade methodology: LakeQuality methodology.
Watch Diamond Lake East Basin; Penn Township water quality
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Swimming Safety
Grade onlyLimited data
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.
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A (Excellent)
Good clarity, visible to about 12.3 ft. Phosphorus level: 6 µg/L. Chlorophyll-a: 2 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 12.3 ft | Not graded |
| Phosphorus | 6 µg/L | Good |
| Chlorophyll-a (Algae) | 2 µg/L | Good |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
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Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 64 ft |
| Surface Area | 1,040 acres |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fishing Diamond Lake East Basin; Penn Township
Water Quality Trend: ↓ Declining
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | +0.104 m/yr | 4 |
| Phosphorus | ↓ Declining | +1.2 µg/L/yr | 4 |
| Chlorophyll-a | ↓ Declining | +0.39 µg/L/yr | 4 |
County Ranking
Ranked #2 of 10 lakes in Cass County
Nearby Lakes in Cass County
Frequently asked questions about Diamond Lake East Basin; Penn Township
Where is Diamond Lake East Basin; Penn Township?
- Diamond Lake East Basin; Penn Township is a lake in Cass County, Michigan. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Diamond Lake East Basin; Penn Township?
- Diamond Lake East Basin; Penn Township in Cass County, Michigan has a water quality grade of A (Excellent). Water clarity: 12.3 ft visibility. Phosphorus: 6 µg/L. Chlorophyll-a (algae): 2 µg/L. Maximum depth: 64 ft. Surface area: 1039.8 acres.
Is Diamond Lake East Basin; Penn Township safe to swim in?
- Excellent for swimming, crystal clear water with minimal algae. Diamond Lake East Basin; Penn Township has a water quality grade of A (Excellent). Algae concentration (chlorophyll-a) is 2 µg/L. Always check local health department advisories before swimming.
How deep is Diamond Lake East Basin; Penn Township?
- Diamond Lake East Basin; Penn Township has a maximum depth of 64 feet. The lake covers 1039.8 acres.
Explore Diamond Lake East Basin; Penn Township across LakeQuality
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Other Grade A Lakes in Michigan
Van Buren County · 14 ft
St. Joseph County · Excellent
Kalamazoo County · 8 ft
St. Joseph County · 6 ft
Kalamazoo County · 9.5 ft
Allegan County · 9 ft
Oligotrophic Lakes in Michigan
Where this data comes from
99 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_MICORPS99 samples · 2016–2019
Analytical methods
- Phosphorus by Colorimetry
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
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
Lake size & watershed from HydroLAKES (HydroSHEDS)