Dark Canyon Lake
San Juan County, UtahView mapDirections
Nutrients and algae sit mid-range for this region.
↓ down from B at the last regrade
- Mesotrophic
- #8 of 10 in the county
- Limited data
Dark Canyon Lake in San Juan County, Utah has a water quality grade of C (Fair). Water clarity: 7.2 ft visibility. Phosphorus: 24.2 µg/L. Chlorophyll-a (algae): 3.2 µg/L.
- Clarity
- 7.2 ft
- Type
- Mesotrophic
- Phosphorus
- 24.2 µg/L
- Chlorophyll-a
- 3.2 µg/L
- Trend
- ↑ Improving
Stays via Stay22
Stays near Dark Canyon Lake
Compare lakeside cabins, hotels, and vacation rentals near Dark Canyon Lake in San Juan County, Utah — 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 Dark Canyon 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.
Planning a whole trip? See where to stay at Utah’s top lakes →
Watch Dark Canyon Lake’s letter
Email me if this lake’s grade moves. Grades stay free.
Or email
Dark Canyon Lake is a mesotrophic lake in San Juan County, Utah. Water quality is graded C based on 2 sampling years through 2025. Overall water quality is improving over recent sampling years. Compared to the 9 other monitored lakes in San Juan County, Dark Canyon Lake ranks #8 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DWQ, last sampled 2025-08-27. Grade methodology: LakeQuality methodology.
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 C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Water Quality Grade: C (Fair)
Moderate clarity, visible to about 7.2 ft. Phosphorus 24.2 µg/L. Chlorophyll-a 3.2 µg/L. TSI 47. The letter is not a swimming clearance.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 7.2 ft | Not graded |
| Phosphorus | 24.2 µg/L | Fair |
| Chlorophyll-a (Algae) | 3.2 µg/L | Fair |
| Trophic State Index (TSI) | 47 | Mesotrophic |
Moderate nutrients, good water quality
Fishing Dark Canyon Lake
Water Quality Trend: ↑ Improving
Based on 2 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↑ Improving | +0.075 m/yr | 2 |
| Chlorophyll-a | ↑ Improving | -0.62 µg/L/yr | 2 |
County Ranking
Ranked #8 of 10 lakes in San Juan County
Nearby Lakes in San Juan County
Frequently asked questions about Dark Canyon Lake
Where is Dark Canyon Lake?
- Dark Canyon Lake is a lake in San Juan County, Utah. LakeQuality grades it C for nutrients and algae. The letter is not a swimming clearance.
What is the water quality grade for Dark Canyon Lake?
- Dark Canyon Lake in San Juan County, Utah has a water quality grade of C (Fair). Water clarity: 7.2 ft visibility. Phosphorus: 24.2 µg/L. Chlorophyll-a (algae): 3.2 µg/L.
Is Dark Canyon Lake safe to swim in?
- The C is nutrients and algae, not a swimming clearance. Check local advisories before you swim.
Explore Dark Canyon Lake across LakeQuality
Planning a trip around Arches?
Dark Canyon Lake is about 28 miles from Arches 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 Arches →More Utah Lake Rankings
Other Grade C Lakes in Utah
Mesotrophic Lakes in Utah
Where this data comes from
18 measurements from 1 monitoring station, 2019–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Utah Department Of Environmental Quality
UTAHDWQ_WQX18 samples · 2019–2025
Analytical methods
- Field Measurements
- Phosphorus by Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
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.