West Thumb Lake
Teton County, WyomingView mapDirections
Not Rated: one monitoring station are on record, but they measured water clarity only. LakeQuality’s A–F method grades total phosphorus, total nitrogen, chlorophyll-a, and turbidity; clarity is shown, not scored.
- Limited data
West Thumb Lake in Teton County, Wyoming is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 31.2 ft visibility.
- Clarity
- 31.2 ft
- Trend
- ↑ Improving
Stays via Stay22
Stays near West Thumb Lake
Compare lakeside cabins, hotels, and vacation rentals near West Thumb Lake in Teton County, Wyoming — 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 West Thumb Lake
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Watch West Thumb Lake’s letter
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Why West Thumb Lake has no grade
West Thumb Lake has monitoring on record from one station, but only water clarity was measured. LakeQuality’s A–F letter uses total phosphorus, total nitrogen, chlorophyll-a, and turbidity against EPA National Lakes Assessment condition classes. With none of those grading measurements on record, West Thumb Lake is Not Rated — not an F. Its 31.2-foot median from 8 readings collected 2012–2013 is still shown as clarity, but clarity alone cannot earn a letter.
Not Rated is EPA Integrated Reporting Category 3 — insufficient information. Everything below that has been measured is still reported on this page.
Sampling is run by Wyoming DEQ and volunteer programs, and published through the EPA Water Quality Portal. Read the full grading methodology.
West Thumb Lake is a lake in Teton County, Wyoming. Overall water quality is improving over recent sampling years.
Source: EPA Water Quality Portal sampling records, Wyoming DEQ, last sampled 2013-09-09. Grade methodology: LakeQuality methodology.
What West Thumb Lake is good for
From access and monitoring records, not editorial picks.
- Clear water31.2 ft of visibility
Swimming Safety
Not ratedLimited data
The letter is not a swimming clearance. Check local advisories before you swim.
Water quality measurements for West Thumb Lake
These readings exist but are not enough for an A–F grade — see why.
Crystal clear, you can see 31.2 ft down. TSI 28.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 31.2 ft | Not graded |
| Phosphorus | No recent samples | |
| Chlorophyll-a (Algae) | No recent samples | |
| Trophic State Index (TSI) | 28 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing West Thumb Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +25 m/yr | 2 |
Nearby Lakes in Teton County
Frequently asked questions about West Thumb Lake
Where is West Thumb Lake?
- West Thumb Lake is a lake in Teton County, Wyoming. LakeQuality has not rated this lake (UNRATED) — the only measurement available is water clarity, which is not a water-quality indicator on its own — EPA's National Lakes Assessment does not grade clarity.
What is the water quality grade for West Thumb Lake?
- West Thumb Lake in Teton County, Wyoming is not rated for water quality — its monitoring record does not meet the evidence bar. Water clarity: 31.2 ft visibility.
Is West Thumb Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
Explore West Thumb Lake across LakeQuality
4 documented falls within 19.5 mi, nearest Lewis Falls
4 thermal springs within 14.1 mi, nearest Steamboat Springs
Species activity outlook by water temperature and season
Where to stay at Wyoming's top lakes, each with its grade
Wyoming's cleanest and most-polluted lakes, ranked
Planning a trip around Yellowstone?
West Thumb Lake is about 11 miles from Yellowstone National Park. Crowds there swing hard by season, so the month you pick changes both how busy the park is and what lodging costs.
Best time to visit Yellowstone →More Wyoming Lake Rankings
Other Lakes in Wyoming
Oligotrophic Lakes in Wyoming
Where this data comes from
8 measurements from 1 monitoring station, 2012–2013. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- National Park Service Water Resources Division
11NPSWRD_WQX8 samples · 2012–2013
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.