What is the water quality grade for Lake O the Pines Mid Lake?

Lake O the Pines Mid Lake in Marion County, Texas received a water quality grade of D (Poor). Water clarity: 2.7 ft visibility. Phosphorus: 30 µg/L. Chlorophyll-a (algae): 41.7 µg/L.

Is Lake O the Pines Mid Lake safe to swim in?

Swimming not recommended, poor water quality with high algae risk. Lake O the Pines Mid Lake has an overall water quality grade of D. Algae concentration (chlorophyll-a) is 41.7 µg/L. Always check local health department advisories before swimming.

Marion County, Texas

Lake O the Pines Mid Lake

Grade DPoor · 2.7 ft clarity

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Eutrophic

Lake O the Pines Mid Lake is a productive, nutrient-rich eutrophic lake in Marion County, Texas. Water quality is graded D based on 2 sampling years through 2025. Compared to the 3 other monitored lakes in Marion County, Lake O the Pines Mid Lake ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, Texas DNR, last sampled 2025-09-16. 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 2.7 ft of visibility. Phosphorus level: 30 µg/L. Chlorophyll-a: 41.7 µg/L. Trophic State Index: 61.

Metric	Value	Grade
Water Clarity (Secchi Depth)	2.7 ft	F
Phosphorus	30 µg/L	C
Chlorophyll-a (Algae)	41.7 µg/L	F
Trophic State Index (TSI)	61	Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Lake O the Pines Mid Lake

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