Long Lake South Central Basin is a mesotrophic lake in Cass County, Michigan. Water quality is graded B based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. The lake supports 25 documented fish species including Blackchin shiner, Blacknose shiner, and Bluegill. Compared to the 22 other monitored lakes in Cass County, Long Lake South Central Basin ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2023-09-22. Grade methodology: LakeGrade methodology.
Watch Long Lake South Central Basin water quality
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Swimming Safety
Good for swimming, clear water with low algae levels
Water Quality Grade: B, Good
Good clarity, visible to about 10.5 ft. Chlorophyll-a: 5.6 µg/L. Trophic State Index: 45.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 5.6 µg/L | B |
| Trophic State Index (TSI) | 45 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Long Lake South Central Basin
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Long Lake South Central Basin
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +1.562 m/yr | 4 |
| Chlorophyll-a | ↑ Improving | -0.35 µg/L/yr | 3 |
Water Temperature
Long Lake South Central Basin averages about 63°F at the surface in summer, usually warmest in Sep (about 65°F) and coldest in May (about 55°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 221 field readings (2022–2023) via the EPA Water Quality Portal. See the full Long Lake South Central Basin water temperature breakdown →
Location
County Ranking
Ranked #5 of 23 lakes in Cass County
Nearby Lakes in Cass County
Explore Long Lake South Central Basin 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
Where to stay at Michigan's top lakes, each with its grade
Moderate nutrients, good water quality
Michigan's cleanest and most-polluted lakes, ranked
More Michigan Lake Rankings
Other Grade B Lakes in Michigan
Van Buren County · Clarity: 11.5 ft
St. Joseph County · Clarity: 10.5 ft
Kalamazoo County · Clarity: 9.5 ft
Kalamazoo County · Clarity: 8 ft
Kalamazoo County · Clarity: 9.5 ft
Allegan County · Clarity: 14 ft
Mesotrophic Lakes in Michigan
More records, surveys & data sources
EPA Impairment Status
Long Lake South Central Basin is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
Source: EPA ATTAINS assessment unit MI040500011303-06 · Official waterbody report · Matched by proximity (0.71 km)
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth is a modeled estimate.
Regulated Pollution Sources Nearby
11 EPA-permitted facilities operate within about 5 miles of Long Lake South Central Basin under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Brinco - The Bristol Indiana Corporation (Dba)Bristol · 4.7 mi away · NPDES IN0064920Recent violation
- Terra Subdivision Section 2Bristol · 3.3 mi away · NPDES INR10L742
- Pinnacle Transport Group York Township SiteBristol · 4.3 mi away · NPDES INRA08693
- Barletta Boats CompanyBristol · 4.7 mi away · NPDES INRA06572
- Bristol Indiana Corporation Dba BrincoBristol · 4.7 mi away · NPDES INRM02761
- Diversified Machine Bristol, Inc.Bristol · 4.8 mi away · NPDES IN0059820
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: 2023-09-22
Monitoring stations: 1