Kolob Reservoir is a cold, clear oligotrophic lake in Washington County, Utah. Water quality is graded A based on 2 sampling years through 2025. Compared to the 14 other monitored lakes in Washington County, Kolob Reservoir ranks #5 for water quality.
Source: EPA Water Quality Portal sampling records, Utah DNR, last sampled 2025-08-18. Grade methodology: LakeGrade methodology.
Watch Kolob Reservoir 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
Good clarity, visible to about 10.5 ft. Chlorophyll-a: 1.8 µg/L. Trophic State Index: 40.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 10.5 ft | B |
| Phosphorus | No data | |
| Chlorophyll-a (Algae) | 1.8 µg/L | A |
| Trophic State Index (TSI) | 40 | Oligotrophic |
Low nutrients, clear water, excellent for swimming
Where to stay near Kolob Reservoir
Compare lakeside cabins, hotels, and vacation rentals near Kolob Reservoir in Washington 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 Kolob Reservoir
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 Kolob Reservoir?
Get lake water-quality report cards plus the best cabin & lodging deals near Kolob Reservoir — straight to your inbox. No spam, unsubscribe anytime.
Fishing Kolob Reservoir
Location
County Ranking
Ranked #5 of 15 lakes in Washington County
Nearby Lakes in Washington County
Explore Kolob Reservoir across LakeGrade
More Utah Lake Rankings
Other Grade A Lakes in Utah
Oligotrophic Lakes in Utah
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: 2025-08-18
Monitoring stations: 1