Eagle Lake West Central Basin; Ontwa Township is a mesotrophic lake in Cass County, Michigan. Water quality is graded B based on 2 sampling years through 2023. Water clarity is improving over recent sampling years. Limited fish-species data available. Public access is available. Compared to the 22 other monitored lakes in Cass County, Eagle Lake West Central Basin; Ontwa Township ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2023-09-21. Grade methodology: LakeGrade methodology.
Watch Eagle Lake West Central Basin; Ontwa Township water quality
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Murky, only visible to about 6.3 ft. Chlorophyll-a: 4.7 µg/L. Trophic State Index: 48.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 6.3 ft | D |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 4.7 µg/L | A |
| Trophic State Index (TSI) | 48 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Eagle Lake West Central Basin; Ontwa Township
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Fishing Eagle Lake West Central Basin; Ontwa Township
Water Quality Trend: → Stable
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.185 m/yr | 4 |
| Chlorophyll-a | ↓ Declining | +0.6 µg/L/yr | 3 |
Water Temperature
Eagle Lake West Central Basin; Ontwa Township averages about 72°F at the surface in summer, usually warmest in Jul (about 74°F) and coldest in May (about 62°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 805 field readings (2010–2023) via the EPA Water Quality Portal. See the full Eagle Lake West Central Basin; Ontwa Township water temperature breakdown →
Location & Depth Map
Free interactive depth-contour map of Eagle Lake West Central Basin; Ontwa Township, reaching a maximum surveyed depth of 35 ft. Toggle Depth contours to overlay the bathymetric survey lines. Contour data from Michigan DNR.
County Ranking
Ranked #9 of 23 lakes in Cass County
Nearby Lakes in Cass County
Explore Eagle Lake West Central Basin; Ontwa Township across LakeGrade
Fish species and top-graded lakes across Michigan
Fish species and best lakes in Cass County
Species activity outlook by water temperature and season
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Moderate nutrients, good water quality
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More Michigan Lake Rankings
Other Grade B Lakes in Michigan
Van Buren County · Clarity: 11.5 ft
Kalamazoo County · Clarity: 9.5 ft
St. Joseph County · Clarity: 10.5 ft
Kalamazoo County · Clarity: 8 ft
Allegan County · Clarity: 14 ft
Kalamazoo County · Clarity: 9.5 ft
Mesotrophic Lakes in Michigan
More records, surveys & data sources
EPA Impairment Status
Eagle Lake West Central Basin; Ontwa Township 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 MI040500011403-04 · Official waterbody report · Matched by proximity (0.32 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
5 EPA-permitted facilities operate within about 5 miles of Eagle Lake West Central Basin; Ontwa Township under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Edwardsburg MS4-CassEdwardsburg · 2.3 mi away · NPDES MI0060074Recent violation
- Service Oil CompanyEdwardsburg · 2.5 mi away · NPDES MIG080855
- Mdeq-Rrd-EdwardsburgEdwardsburg · 2.8 mi away · NPDES MI0051764
- The HavenGranger · 4.8 mi away · NPDES INRA06620
- New Granger Trails Phase TwoGranger · 5 mi away · NPDES INRA00440
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.
Data Sources
Water quality data from the EPA Water Quality Portal
Impairment status from EPA ATTAINS 303(d) database
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-09-21
Monitoring stations: 1