Placid Lake Midlake Hole
Missoula County, MontanaView mapDirections
Clarity, phosphorus, and algae sit in the clean band for this region.
↓ down from A at the last regrade
- Oligotrophic
- #9 of 40 in the county
- Limited data
Placid Lake Midlake Hole in Missoula County, Montana has a water quality grade of B (Good). Water clarity: 16.7 ft visibility.
- Clarity
- 16.7 ft
- Type
- Oligotrophic
- Trend
- → Stable
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Watch Placid Lake Midlake Hole’s letter
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Placid Lake Midlake Hole is a cold, clear oligotrophic lake in Missoula County, Montana. Water quality is graded B based on 1 sampling years through 2021. Phosphorus level is declining over recent sampling years. Compared to the 39 other monitored lakes in Missoula County, Placid Lake Midlake Hole ranks #9 for water quality.
Source: EPA Water Quality Portal sampling records, Montana DEQ, last sampled 2021-07-13. Grade methodology: LakeQuality methodology.
What Placid Lake Midlake Hole is good for
From access and monitoring records, not editorial picks.
- Clear water16.7 ft of visibility
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 B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: B (Good)
Crystal clear, you can see 16.7 ft down. TSI 37. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 16.7 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 37 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing Placid Lake Midlake Hole
Water Quality Trend: → Stable
Based on 12 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | → Stable | -0.005 m/yr | 8 |
| Phosphorus | ↓ Declining | +0.3 µg/L/yr | 4 |
| Chlorophyll-a | ↑ Improving | -1 µg/L/yr | 2 |
County Ranking
Ranked #9 of 40 lakes in Missoula County
Nearby Lakes in Missoula County
Frequently asked questions about Placid Lake Midlake Hole
Where is Placid Lake Midlake Hole?
- Placid Lake Midlake Hole is a lake in Missoula County, Montana. LakeQuality grades it B for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Placid Lake Midlake Hole?
- Placid Lake Midlake Hole in Missoula County, Montana has a water quality grade of B (Good). Water clarity: 16.7 ft visibility.
Is Placid Lake Midlake Hole safe to swim in?
- The B is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Placid Lake Midlake Hole across LakeQuality
Species activity outlook by water temperature and season
Where to stay at Montana's top lakes, each with its grade
Low nutrients, clear water. The letter is not a swimming clearance.
Montana's cleanest and most-polluted lakes, ranked
More Montana Lake Rankings
Other Grade B Lakes in Montana
Oligotrophic Lakes in Montana
Where this data comes from
49 measurements from 1 monitoring station, 2012–2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Montana Volunteer Water Quality Monitoring
MTVOLWQM_WQX49 samples · 2012–2021
Analytical methods
- 4500 N C ~ Persufate Method for Total Nitrogen
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.