Opal Lake
Otsego County, WisconsinLimited DataOligotrophic
Opal Lake is a cold, clear oligotrophic lake in Otsego County, MI. Water quality is graded A based on 1 sampling years through 2021. The lake supports 11 documented fish species including Bluntnose minnow, Common shiner, and Johnny darter. Compared to the 12 other monitored lakes in Otsego County, Opal Lake ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, local state DNR records, last sampled 2021-09-23. Grade methodology: LakeGrade methodology.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
Crystal clear, you can see 18.5 ft down. Trophic State Index: 35.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 18.5 ft | A |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | No data | |
| Trophic State Index (TSI) | 35 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Fish Species
Click a species to see all Wisconsin and Minnesota lakes where it is found.
→ Best fishing times for Opal Lake (14-day solunar calendar)
→ Is it safe to eat fish from Opal Lake? (mercury & PFAS guide)
→ Opal Lake fishing regulations (limits, seasons, special rules)
Location
County Ranking
Ranked #4 of 13 lakes in Otsego County
Nearby Lakes in Otsego County
More Wisconsin Lake Rankings
Other Grade A Lakes in Wisconsin
Mecosta County · Clarity: 12.8 ft
Benzie County · Clarity: 13.5 ft
Clare County · Clarity: 15 ft
Kalkaska County · Clarity: 16 ft
Gogebic County · Clarity: 18 ft
Iron County · Clarity: 16 ft
Oligotrophic Lakes in Wisconsin
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2021-09-23
Monitoring stations: 1