St. Mary's Lake
St. Mary River, British ColumbiaView mapDirections
No A–F letter for this lake. The letter is scored against EPA reference conditions for a lake’s ecoregion, and those stop at the US border. Here is what has been measured.
- Limited data
St. Mary's Lake in St. Mary River, British Columbia has water-quality measurements published by ENV and no A–F letter. The letter's EPA reference conditions stop at the US border. Water clarity: 3.4 m visibility. Phosphorus: 7.4 µg/L. Chlorophyll-a (algae): 0.5 µg/L.
- Clarity
- 3.4 m
Stays via Stay22
Stays near St. Mary's Lake
Compare lakeside cabins, hotels, and vacation rentals near St. Mary's Lake in St. Mary River, British Columbia — 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 St. Mary's Lake
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.
Follow St. Mary's Lake’s readings
Email me when new measurements post for this lake. Updates stay free.
Or email
Why St. Mary's Lake has no A–F letter
The LakeQuality letter is scored against EPA National Lakes Assessment reference conditions for a lake’s ecoregion, and those stop at the US border. There is no reference condition for British Columbia, so the scale cannot be applied to St. Mary's Lake at any level of sampling. Sampling here has recorded water clarity, phosphorus and algae (chlorophyll-a).
This is not a gap in the monitoring record. ENV publishes these measurements directly, and everything below that has been measured is reported on this page as ENV reports it.
Monitoring: the British Columbia Ministry of Environment and Parks. Read the full grading methodology.
St. Mary's Lake is a lake in St. Mary River County, British Columbia.
Source: the British Columbia Ministry of Environment and Parks — not the EPA Water Quality Portal, last sampled 2017-08-24. Grade methodology: LakeQuality methodology.
What St. Mary's Lake is good for
From access and monitoring records, not editorial picks.
- Clear water11.1 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 St. Mary's Lake
These are the measurements ENV publishes for St. Mary's Lake. No A–F letter applies here: see why.
Good clarity, visible to about 11.1 ft. Phosphorus 7.4 µg/L. Chlorophyll-a 0.5 µg/L. TSI 33.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 3.38 m | Measured, not scored |
| Phosphorus | 7.4 µg/L | Measured, not scored |
| Chlorophyll-a (Algae) | 0.5 µg/L | Measured, not scored |
| Trophic State Index (TSI) | 33 | Oligotrophic |
Low nutrients, clear water. The letter is not a swimming clearance.
Fishing St. Mary's Lake
Nearby Lakes in St. Mary River
Frequently asked questions about St. Mary's Lake
Where is St. Mary's Lake?
- St. Mary's Lake is a lake in St. Mary River, British Columbia. Its water-quality measurements are published by ENV, and it carries no A–F letter, because no reference condition exists for lakes in this region, so the assessment thresholds behind the A–F scale cannot be applied here.
What is the water quality grade for St. Mary's Lake?
- St. Mary's Lake in St. Mary River, British Columbia has water-quality measurements published by ENV and no A–F letter. The letter's EPA reference conditions stop at the US border. Water clarity: 3.4 m visibility. Phosphorus: 7.4 µg/L. Chlorophyll-a (algae): 0.5 µg/L.
Is St. Mary's Lake safe to swim in?
- The letter is not a swimming clearance. Check local advisories before you swim.
Explore St. Mary's Lake across LakeQuality
More lakes in British Columbia
Other Lakes in British Columbia
Oligotrophic Lakes in British Columbia
Where this data comes from
6 measurements from 1 monitoring station, 2017. Retrieved from British Columbia EnMoDS (not the EPA Water Quality Portal) on 2026-09-06.
Collected and reported by
- British Columbia Ministry of Environment and Parks
enmods-bc6 samples · 2017
Monitoring station identifiers (1)
E308528
Canadian lakes are published with the measurements their provincial programme reports, and without a LakeQuality A–F letter. The letter is scored against EPA reference conditions for a lake’s ecoregion, and the EPA does not survey these lakes. See how grades are calculated and data sources.