Swan Lake North End
Lake County, MontanaView mapDirections
Clarity, phosphorus, and algae all sit in the cleanest band for this region.
- Oligotrophic
- #2 of 18 in the county
Swan Lake North End in Lake County, Montana has a water quality grade of A (Excellent). Phosphorus: 3.1 µg/L. Chlorophyll-a (algae): 1.1 µg/L.
- Type
- Oligotrophic
- Phosphorus
- 3.1 µg/L
- Chlorophyll-a
- 1.1 µg/L
- Trend
- ↓ Declining
Stays via Stay22
Stays near Swan Lake North End
Compare lakeside cabins, hotels, and vacation rentals near Swan Lake North End in Lake 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 Swan Lake North End
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 Montana’s top lakes →
Watch Swan Lake North End’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Swan Lake North End is a cold, clear oligotrophic lake in Lake County, Montana. Water quality is graded A based on 3 sampling years through 2023. Overall water quality is declining over recent sampling years. Compared to the 17 other monitored lakes in Lake County, Swan Lake North End ranks #2 for water quality.
Source: EPA Water Quality Portal sampling records, Montana DEQ, last sampled 2023-08-02. Grade methodology: LakeQuality methodology.
Swimming Safety
Grade onlyLow algae
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)
No clarity data. Phosphorus 3.1 µg/L. Chlorophyll-a 1.1 µg/L. TSI 26. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | No recent samples | |
| Phosphorus | 3.1 µg/L | Good |
| Chlorophyll-a (Algae) | 1.1 µg/L | Good |
| Trophic State Index (TSI) | 26 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing Swan Lake North End
Water Quality Trend: ↓ Declining
Based on 11 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Phosphorus | → Stable | -0.03 µg/L/yr | 11 |
| Chlorophyll-a | ↓ Declining | +0.04 µg/L/yr | 11 |
County Ranking
Ranked #2 of 18 lakes in Lake County
Nearby Lakes in Lake County
Frequently asked questions about Swan Lake North End
Where is Swan Lake North End?
- Swan Lake North End is a lake in Lake County, Montana. LakeQuality grades it A for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Swan Lake North End?
- Swan Lake North End in Lake County, Montana has a water quality grade of A (Excellent). Phosphorus: 3.1 µg/L. Chlorophyll-a (algae): 1.1 µg/L.
Is Swan Lake North End safe to swim in?
- The A is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Swan Lake North End 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 A Lakes in Montana
Oligotrophic Lakes in Montana
Where this data comes from
53 measurements from 1 monitoring station, 2012–2023. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Montana Watershed
MTWTRSHD_WQX53 samples · 2012–2023
Analytical methods
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
- 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.