Well water in La Salle County, Texas
In La Salle County, none of 73 tested well samples exceeded the EPA limit for fluoride, based on public data from Texas Water Development Board Groundwater Database and USGS Water Quality Portal.
84 individual samples from 33 wells, 1942 to 2016. 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 La Salle 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.
| Contaminant | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| Fluoride 1959 to 2010 | 73 | 100% | 0% | 0.62 | 2.5 | 4 mg/L EPA limit | |
| Nitrate 1962 to 2010 | 34 | 56% | 0% | 0.025 | 1.8 | 10 mg/L EPA limit | |
| Arsenic 1990 to 2016 | 33 | 6% | 0% | 0 | 5.2 | 10 ug/L EPA limit | |
| Lead 1990 to 2015 | 33 | 3% | 0% | 0 | 0.073 | 15 ug/L EPA limit | |
| Copper 1990 to 2010 | 32 | 66% | 0% | 0.003 | 0.046 | 1.3 mg/L EPA limit | |
| Sodium 1942 to 2010 | 84 | 100% | no limit | 295 | 1,800 | 20 mg/L health guideline | |
| Chloride 1942 to 2010 | 83 | 100% | no limit | 156 | 1,740 | 250 mg/L nuisance level | |
| Iron 1962 to 2016 | 59 | 93% | no limit | 155 | 3,820 | 300 ug/L nuisance level | |
| Manganese 1990 to 2010 | 32 | 88% | no limit | 13.4 | 387 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: Gross alpha (7), Uranium (7), Radium (226 + 228) (4), E. coli (2), Radon (2).
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What this means
Among contaminants with a federal limit, no tested sample in La Salle County came back above it. That is reassuring, but sampling is uneven: wells that were never tested are not in this data.
Chloride, Iron, and Manganese 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 La Salle County
- Volatile organic compounds (VOCs)17 leaking underground storage tank sites on record locally.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 242 pCi/L.
- FluorideDetected in 100% of local samples.
- ChlorideDetected in 100% of local samples.
- NitrateRecommended for every private well, especially near farms or septic systems.
- IronDetected in 93% of local samples.
- ManganeseDetected in 88% of local samples.
Contamination sources on record in La Salle County
TCEQ records 17 leaking underground storage tank sites in La Salle County, among 20 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.
- 17
- 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
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Copper
- Neutralizing filter to raise pH; Point-of-use reverse osmosis
- Chloride
- Point-of-use reverse osmosis; Distillation
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
- Manganese
- Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Get your La Salle County water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves La Salle County.
Common questions
Is there arsenic in well water in La Salle County?
Arsenic was detected in 6% of 33 public well samples in La Salle County, and 0% 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 La Salle County?
The median radon level across 2 public samples in La Salle County was 242 pCi/L, with a high of 390 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in La Salle 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: 463 samples in La Salle 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: 22 samples in La Salle 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: 20 regulated sites located in La Salle 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.