What is the water quality grade for Lewisville Lake?

Lewisville Lake in Denton County, Texas received a water quality grade of C (Fair). Water clarity: 1.8 ft visibility. Phosphorus: 43 µg/L. Chlorophyll-a (algae): 26.8 µg/L.

Is Lewisville Lake safe to swim in?

Swim with caution, moderate algae may be present. Lewisville Lake has an overall water quality grade of C. Algae concentration (chlorophyll-a) is 26.8 µg/L. Always check local health department advisories before swimming.

Denton County, Texas

Lewisville Lake

Grade CFair · 1.8 ft clarity

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Eutrophic

Lewisville Lake is a productive, nutrient-rich eutrophic lake in Denton County, Texas. Water quality is graded C based on 2 sampling years through 2026. Compared to the 5 other monitored lakes in Denton County, Lewisville Lake ranks #2 for water quality.

Source: EPA Water Quality Portal sampling records, Texas DNR, last sampled 2026-01-13. Grade methodology: LakeGrade methodology.

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Swimming Safety

Swim with caution, moderate algae may be present

Water Quality Grade: C, Fair

Very murky, less than 1.8 ft of visibility. Phosphorus level: 43 µg/L. Chlorophyll-a: 26.8 µg/L. Trophic State Index: 63.

Metric	Value	Grade
Water Clarity (Secchi Depth)	1.8 ft	F
Phosphorus	43 µg/L	C
Chlorophyll-a (Algae)	26.8 µg/L	D
Trophic State Index (TSI)	63	Eutrophic

High nutrients, frequent algae, reduced clarity

Where to stay near Lewisville Lake

Compare lakeside cabins, hotels, and vacation rentals near Lewisville Lake in Denton County, Texas — 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 Lewisville Lake