Well Water Nerd

Well water in Yoakum County, Texas

In Yoakum County, 71% of 63 tested well samples exceeded the EPA limit for arsenic (10 ug/L), based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.

70 individual samples from 33 wells, 1962 to 2024. Data refreshed September 9, 2026.

TWDB samples an ambient monitoring network of wells on a rotation, so these describe aquifers, not a survey of homeowners' tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Yoakum County. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

ContaminantSamplesDetectedAbove limitMedianHighestLimit
Arsenic
1990 to 2024
6390%71%14.180.210 ug/L
EPA limit
Fluoride
1962 to 2024
70100%41%3.756.764 mg/L
EPA limit
Nitrate
1990 to 2024
63100%22%4.7433.910 mg/L
EPA limit
Gross alpha
1990 to 2024
1493%7%8.3727.615 pCi/L
EPA limit
Lead
1990 to 2024
632%0%00.28315 ug/L
EPA limit
Copper
1990 to 2024
6351%0%0.0010.0731.3 mg/L
EPA limit
Uranium
2001 to 2024
33100%0%6.2116.130 ug/L
EPA limit
Radium (226 + 228)
1990 to 2012
1872%0%0.4064.45 pCi/L
EPA limit
Chloride
1962 to 2024
70100%no limit19413,898250 mg/L
nuisance level
Sodium
1962 to 2024
70100%no limit1154,72020 mg/L
health guideline
Iron
1990 to 2024
6252%no limit4.63430300 ug/L
nuisance level
Manganese
1990 to 2024
6232%no limit0582300 ug/L
health guideline

Sampled fewer than 10 times, too few to summarize: Radon (2).

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What this means

The contaminants most often above their limit here are arsenic (71% of 63 samples), fluoride (41% of 70 samples), and nitrate (22% of 63 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride and Iron are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Yoakum County

  • Volatile organic compounds (VOCs)22 leaking underground storage tank sites on record locally.
  • Arsenic71% of 63 local samples were above the limit.
  • Fluoride41% of 70 local samples were above the limit.
  • Nitrate22% of 63 local samples were above the limit.
  • Gross alpha7% of 14 local samples were above the limit.
  • Coliform bacteriaRecommended for every private well, every year.
  • RadonMedian local reading is 485 pCi/L.
  • ChlorideDetected in 100% of local samples.

Contamination sources on record in Yoakum County

TCEQ records 22 leaking underground storage tank sites in Yoakum County, among 25 regulated sites in total. Groundwater does not follow property lines, so a well within a few hundred feet of one of these is worth testing for what that site could release.

22
leaking underground storage tank sitesGasoline and heating oil that leaked from tanks move through groundwater as benzene, MTBE and other volatile organic compounds.
3
lined landfills and transfer facilities

Treatment that fits the local profile

Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Fluoride
Point-of-use reverse osmosis; Activated alumina; Distillation
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Gross alpha
Point-of-use reverse osmosis; Water softener (cation exchange) for radium; Anion exchange for uranium
Copper
Neutralizing filter to raise pH; Point-of-use reverse osmosis

Get your Yoakum County water tested at home

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Common questions

Is there arsenic in well water in Yoakum County?

Arsenic was detected in 90% of 63 public well samples in Yoakum County, and 71% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in Yoakum County?

The median radon level across 2 public samples in Yoakum County was 485 pCi/L, with a high of 530 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Yoakum County?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Sources

  • Texas Water Development Board Groundwater Database: 622 samples in Yoakum County. Water quality samples from the Texas Water Development Board Groundwater Database, collected by TWDB, groundwater conservation districts and cooperators. Retrieved September 9, 2026.
  • USGS Water Quality Portal: 31 samples in Yoakum County. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
  • TCEQ regulated sites: 25 regulated sites located in Yoakum County. Leaking petroleum storage tank sites, state Superfund sites and municipal solid waste landfills from the Texas Commission on Environmental Quality. Retrieved September 9, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.