Pentwater Lake is a mesotrophic lake in Oceana County, Michigan. Water quality is graded C based on 1 sampling years through 2022. Overall water quality is improving over recent sampling years. The lake supports 1 documented fish species including Brown trout. Public access is available with 1 public boat landing. Compared to the 4 other monitored lakes in Oceana County, Pentwater Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2022-09-30. Grade methodology: LakeGrade methodology.
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Swimming Safety
Generally safe for swimming, moderate water quality
Water Quality Grade: C, Fair
Moderate clarity, visible to about 7 ft. Trophic State Index: 49.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7 ft | C |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 49 | Mesotrophic |
Moderate nutrients, good water quality
Where to stay near Pentwater Lake
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Fish Species
Click a species to see every graded lake where it is documented.
Fishing Pentwater Lake
Water Quality Trend: ↑ Improving
Based on 4 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.105 m/yr | 4 |
| Chlorophyll-a | ↑ Improving | -1.6 µg/L/yr | 3 |
Recreation & Access
Location
County Ranking
Ranked #4 of 5 lakes in Oceana County
Cleaner Lakes Within 30 Miles
Pentwater Lake holds Grade C. 3 nearby lakes hold higher grades.
Nearby Lakes in Oceana County
Explore Pentwater Lake across LakeGrade
Fish species and top-graded lakes across Michigan
Fish species and best lakes in Oceana 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 C Lakes in Michigan
Mason County · Clarity: 6.5 ft
Muskegon County · Clarity: 6.8 ft
Lake County · Clarity: 8 ft
Muskegon County · Clarity: 8.5 ft
Manistee County · Clarity: 8 ft
Newaygo County · Clarity: 4.5 ft
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.
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Pentwater Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Pentwater CwpPentwater · 0.7 mi away · NPDES MI0058875Recent violation
- Blarney Castle OilHart · 3.4 mi away · NPDES MIG080727
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)
Lake size & watershed from HydroLAKES (HydroSHEDS)
Grading methodology based on Metropolitan Council standards
Public boat-access points from the USGS National Boat Ramps inventory
Most recent sample: 2022-09-30
Monitoring stations: 1