O'Rourke Lake; Bagley Twp is a cold, clear oligotrophic lake in Otsego County, Michigan. Water quality is graded A based on 2 sampling years through 2023. Overall water quality is improving over recent sampling years. Compared to the 12 other monitored lakes in Otsego County, O'Rourke Lake; Bagley Twp ranks #7 for water quality.
Source: EPA Water Quality Portal sampling records, Michigan DNR, last sampled 2023-09-17. Grade methodology: LakeGrade methodology.
Watch O'Rourke Lake; Bagley Twp water quality
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Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 15 ft down. Chlorophyll-a: 1.3 µg/L. Trophic State Index: 36.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 15 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 1.3 µg/L | A |
| Trophic State Index (TSI) | 36 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near O'Rourke Lake; Bagley Twp
Compare lakeside cabins, hotels, and vacation rentals near O'Rourke Lake; Bagley Twp in Otsego 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 O'Rourke Lake; Bagley Twp
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Fishing O'Rourke Lake; Bagley Twp
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +9.78 m/yr | 2 |
Water Temperature
O'Rourke Lake; Bagley Twp averages about 49°F at the surface in summer, usually warmest in Aug (about 51°F) and coldest in May (about 44°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 216 field readings (2023–2023) via the EPA Water Quality Portal. See the full O'Rourke Lake; Bagley Twp water temperature breakdown →
Location
County Ranking
Ranked #7 of 13 lakes in Otsego County
Nearby Lakes in Otsego County
Explore O'Rourke Lake; Bagley Twp across LakeGrade
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Species activity outlook by water temperature and season
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Low nutrients, clear water, excellent for swimming
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Other Grade A Lakes in Michigan
Charlevoix County · Clarity: 17 ft
Cheboygan County · Clarity: 32 ft
Montmorency County · Clarity: 13 ft
Kalkaska County · Clarity: 13.5 ft
Kalkaska County · Clarity: 18.5 ft
Kalkaska County · Excellent
Oligotrophic 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
1 EPA-permitted facility operate within about 5 miles of O'Rourke Lake; Bagley Twp under Clean Water Act (NPDES) discharge permits.
- Hayes Cc CpfGaylord · 2.5 mi away · NPDES MIG081051
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
Most recent sample: 2023-09-17
Monitoring stations: 1