Lake Koocanusa is a cold, clear oligotrophic lake in Lincoln County, Montana. Water quality is graded A based on 2 sampling years through 2023. Compared to the 25 other monitored lakes in Lincoln County, Lake Koocanusa ranks #4 for water quality.
Source: EPA Water Quality Portal sampling records, Montana DNR, last sampled 2023-12-12. Grade methodology: LakeGrade methodology.
Watch Lake Koocanusa water quality
Subscribe for LakeQuality updates by email. No spam, unsubscribe anytime.
Swimming Safety
Excellent for swimming, crystal clear water with minimal algae
Water Quality Grade: A, Excellent
No clarity data. Phosphorus level: 4.5 µg/L. Chlorophyll-a: 1.4 µg/L. Trophic State Index: 30.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No data | |
| Phosphorus | 4.5 µg/L | A |
| Chlorophyll-a (Algae) | 1.4 µg/L | A |
| Trophic State Index (TSI) | 30 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Lake Koocanusa
Compare lakeside cabins, hotels, and vacation rentals near Lake Koocanusa in Lincoln County, Montana — 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 Lake Koocanusa
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 trip to Lake Koocanusa?
Get lake water-quality report cards plus the best cabin & lodging deals near Lake Koocanusa — straight to your inbox. No spam, unsubscribe anytime.
Fishing Lake Koocanusa
Location
County Ranking
Ranked #4 of 26 lakes in Lincoln County
Nearby Lakes in Lincoln County
Explore Lake Koocanusa across LakeGrade
More Montana Lake Rankings
Other Grade A Lakes in Montana
Flathead County · Excellent
Flathead County · Clarity: 21.9 ft
Flathead County · Excellent
Flathead County · Clarity: 20.5 ft
Flathead County · Clarity: 21 ft
Flathead County · Excellent
Oligotrophic Lakes in Montana
More records, surveys & data sources
Data Sources
Water quality data from the EPA Water Quality Portal
Grading methodology based on Metropolitan Council standards
Most recent sample: 2023-12-12
Monitoring stations: 1