What is the water quality grade for South Holston Lake?

South Holston Lake in Washington County, Virginia received a water quality grade of B (Good). Water clarity: 7.2 ft visibility. Phosphorus: 20 µg/L. Chlorophyll-a (algae): 7.5 µg/L.

Is South Holston Lake safe to swim in?

Good for swimming, clear water with low algae levels. South Holston Lake has an overall water quality grade of B. Algae concentration (chlorophyll-a) is 7.5 µg/L. Always check local health department advisories before swimming.

Washington County, Virginia

South Holston Lake

Grade BGood · 7.2 ft clarity

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Mesotrophic

South Holston Lake is a mesotrophic lake in Washington County, Virginia. Water quality is graded B based on 2 sampling years through 2026. Compared to the 1 other monitored lakes in Washington County, South Holston Lake ranks #2 for water quality.

Source: EPA Water Quality Portal sampling records, Virginia DNR, last sampled 2026-07-08. Grade methodology: LakeGrade methodology.

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Swimming Safety

Good for swimming, clear water with low algae levels

Water Quality Grade: B, Good

Moderate clarity, visible to about 7.2 ft. Phosphorus level: 20 µg/L. Chlorophyll-a: 7.5 µg/L. Trophic State Index: 49.

Metric	Value	Grade
Water Clarity (Secchi Depth)	7.2 ft	C
Phosphorus	20 µg/L	B
Chlorophyll-a (Algae)	7.5 µg/L	C
Trophic State Index (TSI)	49	Mesotrophic

Moderate nutrients, good water quality

Where to stay near South Holston Lake

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