What is the water quality grade for Flaming Gorge Reservoir?

Flaming Gorge Reservoir in Sweetwater County, Wyoming received a water quality grade of A (Excellent). Water clarity: 22 ft visibility. Phosphorus: 11 µg/L. Chlorophyll-a (algae): 1.1 µg/L.

Is Flaming Gorge Reservoir safe to swim in?

Excellent for swimming, crystal clear water with minimal algae. Flaming Gorge Reservoir has an overall water quality grade of A. Algae concentration (chlorophyll-a) is 1.1 µg/L. Always check local health department advisories before swimming.

Sweetwater County, Wyoming · 41.18°N

Flaming Gorge Reservoir

Grade AExcellent · 22 ft clarity

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Oligotrophic

Flaming Gorge Reservoir is a cold, clear oligotrophic lake in Sweetwater County, Wyoming. Water quality is graded A based on 3 sampling years through 2025. Compared to the 14 other monitored lakes in Sweetwater County, Flaming Gorge Reservoir ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, Wyoming DNR, last sampled 2025-07-09. Grade methodology: LakeGrade methodology.

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Swimming Safety

Excellent for swimming, crystal clear water with minimal algae

Water Quality Grade: A, Excellent

Crystal clear, you can see 22 ft down. Phosphorus level: 11 µg/L. Chlorophyll-a: 1.1 µg/L. Trophic State Index: 34.

Metric	Value	Grade
Water Clarity (Secchi Depth)	22 ft	A
Phosphorus	11 µg/L	A
Chlorophyll-a (Algae)	1.1 µg/L	A
Trophic State Index (TSI)	34	Oligotrophic

Low nutrients, clear water, excellent for swimming

Where to stay near Flaming Gorge Reservoir

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