Osterhout Lake
Allegan County, MichiganView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
↑ up from C at the last regrade
- Mesotrophic
- #2 of 5 in the county
- Limited data
Osterhout Lake in Allegan County, Michigan has a water quality grade of A (Excellent). Water clarity: 9 ft visibility. Phosphorus: 14 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
- Clarity
- 9 ft
- Type
- Mesotrophic
- Trend
- ↓ Declining
Stays via Stay22
Stays near Osterhout Lake
Compare lakeside cabins, hotels, and vacation rentals near Osterhout Lake in Allegan 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.
Top-rated places to stay near Osterhout Lake
Prices for Sep 11–13, 4 adults. Change dates on the map below.
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Planning a whole trip? See where to stay at Michigan’s top lakes →
Watch Osterhout Lake’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Osterhout Lake is a mesotrophic lake in Allegan County, Michigan. Water quality is graded A based on 2 sampling years through 2023. Overall water quality is declining over recent sampling years. Compared to the 4 other monitored lakes in Allegan County, Osterhout Lake ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, EGLE, last sampled 2023-09-21. Grade methodology: LakeQuality methodology.
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.
The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: A (Excellent)
Moderate clarity, visible to about 9 ft. Phosphorus 14 µg/L. Chlorophyll-a 2.8 µg/L. TSI 43. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 9 ft | Not graded |
| Phosphorus | 14 µg/L | Good |
| Chlorophyll-a (Algae) | 2.8 µg/L | Good |
| Trophic State Index (TSI) | 43 | Mesotrophic |
Moderate nutrients, good water quality
Fishing Osterhout Lake
Water Quality Trend: ↓ Declining
Based on 7 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.238 m/yr | 6 |
| Phosphorus | ↓ Declining | +1.25 µg/L/yr | 7 |
| Chlorophyll-a | ↓ Declining | +0.7 µg/L/yr | 2 |
Regulated Pollution Sources Nearby
2 EPA-permitted facilities operate within about 5 miles of Osterhout Lake under Clean Water Act (NPDES) discharge permits. 1 facility has a reported Clean Water Act violation in the past three years.
- Pullman Industries Inc.Pullman · 3.5 mi away · NPDES MIG250128Recent violation
- Antioch Packing HouseAntioch · 4.6 mi away · NPDES IL0067733
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.
County Ranking
Ranked #2 of 5 lakes in Allegan County
Nearby Lakes in Allegan County
Frequently asked questions about Osterhout Lake
Where is Osterhout Lake?
- Osterhout Lake is a lake in Allegan County, Michigan. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Osterhout Lake?
- Osterhout Lake in Allegan County, Michigan has a water quality grade of A (Excellent). Water clarity: 9 ft visibility. Phosphorus: 14 µg/L. Chlorophyll-a (algae): 2.8 µg/L.
Is Osterhout Lake safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Osterhout Lake across LakeQuality
Fish species and top-graded lakes across Michigan
Fish species and best lakes in Allegan 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 A Lakes in Michigan
Mesotrophic Lakes in Michigan
Where this data comes from
109 measurements from 1 monitoring station, 2016–2023. Retrieved from the EPA Water Quality Portal on 2026-08-26.
Collected and reported by
- Michigan EGLE - MiCorps
21MICH_MICORPS109 samples · 2016–2023
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
Regulated discharger data from EPA ECHO (ICIS-NPDES)