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LakeQuality

Lake Thom-A-Lex

Davidson County, North Carolina650 acresView mapDirections

F
Algae-prone

Nutrients and algae run well above the regional average.

↓ down from D at the last regrade

Water temp
No reading
No gauge
Clarity
No reading
No sample
Level
No reading
No gauge
Trend
No reading
Not enough history
  • Hypereutrophic
  • #1 of 2 in the county
  • 42 ft max depth
  • Limited data
See the measurementsDirectionsWhere to stay

Lake Thom-A-Lex in Davidson County, North Carolina has a water quality grade of F (Algae-prone). Phosphorus: 55 µg/L. Chlorophyll-a (algae): 40 µg/L. Surface area: 650 acres.

Max depth
~42 ft est.
Area
650 acres
Type
Hypereutrophic
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Stays via Stay22

Stays near Lake Thom-A-Lex

Compare lakeside cabins, hotels, and vacation rentals near Lake Thom-A-Lex in Davidson County, North Carolina — 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. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Lake Thom-A-Lex are listed below.

Top-rated places to stay near Lake Thom-A-Lex

Prices for Sep 4–6, 4 adults. Change dates on the map below.

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Lake Thom-A-Lex is a 650-acre highly nutrient-loaded hypereutrophic lake in Davidson County, North Carolina with an estimated average depth of about 42 feet. Water quality is graded F based on 2 sampling years through 2021. Compared to the 1 other monitored lakes in Davidson County, Lake Thom-A-Lex ranks #1 for water quality.

Source: EPA Water Quality Portal sampling records, NCDEQ, last sampled 2021-09-28. Grade methodology: LakeQuality methodology.

Swimming Safety

Grade only

Limited data

Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.

The F is nutrients and algae, not a swimming clearance. Lake Thom-A-Lex is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.

Get alerts for Lake Thom-A-Lex →

Water Quality Grade: F (Algae-prone)

No clarity data. Phosphorus 55 µg/L. Chlorophyll-a 40 µg/L. TSI 64. The letter is not a swimming clearance.

MetricValueGrade
Water Clarity (Secchi Depth)No recent samples
Phosphorus55 µg/LPoor
Chlorophyll-a (Algae)40 µg/LPoor
Trophic State Index (TSI)64Hypereutrophic

Very high nutrients, dense algae, poor clarity

Lake Details

CharacteristicValue
Maximum Depth~42 ft est.
Average Depth~20 ft est.
Surface Area650 acres

Depth marked “est.” is a modeled maximum from GLOBathy (Khazaei et al. 2022, CC0), not a measured survey. North Carolina has not published bathymetry for Lake Thom-A-Lex.

Lake Size & Watershed

Watershed (drainage) area
70 sq mi
Shoreline
8.7 mi
Elevation
702 ft

Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS). Mean depth here is modelled, not surveyed — HydroLAKES v1.0 estimates lake depth from surrounding terrain rather than from soundings. Treat it as an approximation, and prefer a state bathymetric survey where one exists.

Fishing Lake Thom-A-Lex

Reservoir Info (USACE NID)

Lake Thom-A-Lex is a man-made reservoir impounded by the Lake Thom-A-Lex Dam (completed 1957), built primarily for water supply on the Abbotts Creek; earth-type dam, 43 ft tall and 635 ft long.

Surface area
650 ac
Normal storage
8,320 ac-ft
Max storage
11,180 ac-ft
Drainage area
69.71 sq mi
Hazard class
High
Owner
City of Lexington

Source: USACE National Inventory of Dams, NID ID NC00178 · Operator website

EPA Impairment Status

Lake Thom-A-Lex is officially listed as impaired under Clean Water Act §303(d) in the 2022 EPA reporting cycle (IR category 5).

Causes of impairment

Algal growth

Source: EPA ATTAINS assessment unit NC12-119-(4.5)b · Official waterbody report · Matched by proximity (1.49 km)

County Ranking

Ranked #1 of 2 lakes in Davidson County

Nearby Lakes With Higher Grades

Lake Thom-A-Lex holds Grade F. One nearby lake has a higher nutrient-and-algae grade — useful for a swim day, not a reason to skip lodging here.

DBack Creek Lake· 20.5 mi

Nearby Lakes in Davidson County

NRLake Tom-A-Lex—View →NRCity Lake—View →NRCobles Reservoir—View →FHigh Rock LakeHypereutrophic17.8 miView →

Frequently asked questions about Lake Thom-A-Lex

Where is Lake Thom-A-Lex?

Lake Thom-A-Lex is a lake in Davidson County, North Carolina. LakeQuality grades it F for nutrients and algae. The letter is not a swimming clearance.

What is the water quality grade for Lake Thom-A-Lex?

Lake Thom-A-Lex in Davidson County, North Carolina has a water quality grade of F (Algae-prone). Phosphorus: 55 µg/L. Chlorophyll-a (algae): 40 µg/L. Surface area: 650 acres.

Is Lake Thom-A-Lex safe to swim in?

The F is nutrients and algae, not a swimming clearance. Lake Thom-A-Lex is listed impaired under Clean Water Act §303(d) (IR 5) for algal growth. Check local advisories before you swim.

How deep is Lake Thom-A-Lex?

No published bathymetric survey covers Lake Thom-A-Lex, so its depth has not been measured. The HydroLAKES global model estimates an average depth of about 42 feet, but that is a modelled estimate derived from surrounding terrain rather than a measurement on the water, so treat it as approximate. The lake covers 650 acres.

Explore Lake Thom-A-Lex across LakeQuality

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Where this data comes from

30 measurements from 2 monitoring stations, 2021. Retrieved from the EPA Water Quality Portal on 2026-08-02.

Collected and reported by

  • North Carolina Dept of Environmental Quality NCDEQ-DWR WQX21NC03WQ30 samples · 2021

Analytical methods

  • Phosphorus by Colorimetry
  • 445.0 ~ EPA; Chlorophyll and Pheophytin in Algae by Fluorescence
  • 2130 B ~ Nephelometric Method
Monitoring station identifiers (2)

Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.

Other records on this page

Impairment status from EPA ATTAINS 303(d) database

Lake size & watershed from HydroLAKES (HydroSHEDS)