What is the water quality grade for Sam Rayburn Reservoir?

Sam Rayburn Reservoir in San Augustine County, Texas received a water quality grade of D (Poor). Water clarity: 1.8 ft visibility. Phosphorus: 60 µg/L. Chlorophyll-a (algae): 23.6 µg/L.

Is Sam Rayburn Reservoir safe to swim in?

Swimming not recommended, poor water quality with high algae risk. Sam Rayburn Reservoir has an overall water quality grade of D. Algae concentration (chlorophyll-a) is 23.6 µg/L. Always check local health department advisories before swimming.

San Augustine County, Texas · 31.27°N

Sam Rayburn Reservoir

Grade DPoor · 1.8 ft clarity

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Eutrophic

Sam Rayburn Reservoir is a productive, nutrient-rich eutrophic lake in San Augustine County, Texas. Water quality is graded D based on 2 sampling years through 2025. Compared to the 2 other monitored lakes in San Augustine County, Sam Rayburn Reservoir ranks #3 for water quality.

Source: EPA Water Quality Portal sampling records, Texas DNR, last sampled 2025-12-09. Grade methodology: LakeGrade methodology.

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Swimming Safety

Swimming not recommended, poor water quality with high algae risk

Water Quality Grade: D, Poor

Very murky, less than 1.8 ft of visibility. Phosphorus level: 60 µg/L. Chlorophyll-a: 23.6 µg/L. Trophic State Index: 64.

Metric	Value	Grade
Water Clarity (Secchi Depth)	1.8 ft	F
Phosphorus	60 µg/L	D
Chlorophyll-a (Algae)	23.6 µg/L	D
Trophic State Index (TSI)	64	Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Sam Rayburn Reservoir

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