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Siesta Shores WCID

What EPA’s and Texas’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves
1,893 people
Connections
631
Water source
Surface water
Based in
Zapata, TX
County
Zapata
Owner
Local government
The ZIP code it serves

78076

The short answer

1 result is above EPA’s legal limit, and 1 more is above the health goal. The worst: Total trihalomethanes (TTHM), above the legal limit. 16 health-based violations since 2016.

What handles it

What was found

Total trihalomethanes (TTHM), uranium, haloacetic acids (HAA5), fluoride, nitrate, arsenic and chromium (total): Texas’s own results, samples taken from Feb. 6, 2020 to Aug. 12, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit1

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the legal limit

68ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 68 ppb, in 2026, below EPA’s legal limit of 80 ppb. Its highest single sample was 189 ppb. That was also the latest year on file. EPA judges this limit at each sampling point, and recorded a violation for total trihalomethanes (TTHM) at this utility in 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 91.5 ppb, in 2017, and EPA recorded violations in 2017, 2018 and 2019.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Above the health goal1

Uranium

Comes from the source

Above the health goal

2.1ppb

Highest yearly average, 2024

Averaged by year, the highest was 2.1 ppb, in 2024: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That is the only year on file.

What handles it

Below EPA’s limits3

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

26.4ppb

Highest yearly average, 2020 to 2026

2026 average: 14.9 ppb

Averaged by year, the highest was 26.4 ppb, in 2024, below EPA’s legal limit of 60 ppb. Its highest single sample was 91.9 ppb. In 2026, the latest year on file, its six samples averaged 14.9 ppb. EPA recorded no violation for haloacetic acids (HAA5) at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 61.1 ppb, in 2017, and EPA recorded violations in 2017 and 2018.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.61ppm

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 0.61 ppm, in 2023, below EPA’s legal limit of 4.0 ppm. In 2025, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.53 ppm, in 2018.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

1.4ppm

Highest sample; found in 6 of 6

2025, one sample: 0.36 ppm

The highest sample, in 2024, was 1.4 ppm, below EPA’s legal limit of 10 ppm. In 2025, the latest year on file, its one sample was 0.36 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 0.64 ppm, in 2019.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Lead

What handles it

A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”

  • NSF/ANSI 53

    Claim: Trihalomethanes (TTHM) Reduction

    For: Total trihalomethanes (TTHM)

    Other certifiers’ wording: VOC Reduction

  • NSF/ANSI 58

    Claims: Trihalomethanes (TTHM) Reduction, Uranium

    For: Total trihalomethanes (TTHM), Uranium

At the tap, or for the whole house?

These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. How whole-house systems compare.

Filters with those claims on a certifier’s listing

Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

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Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2020 to June 30, 20200.095 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2020 to March 31, 20200.092 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2019 to Dec. 31, 20190.097 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2018 to Sept. 30, 20180.087 MG/LResolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2018 to June 30, 20180.073 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2018 to June 30, 20180.12 MG/LResolved
Interim Enhanced Surface Water Treatment RuleToo many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR)March 1, 2018 to March 31, 2018—Resolved
Interim Enhanced Surface Water Treatment RuleToo many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR)Feb. 1, 2018 to Feb. 28, 2018—Resolved
Interim Enhanced Surface Water Treatment RuleToo many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR)Jan. 1, 2018 to Jan. 31, 2018—Resolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2018 to March 31, 20180.071 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2018 to March 31, 20180.1 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2017 to Dec. 31, 20170.093 MG/LResolved
Interim Enhanced Surface Water Treatment RuleToo many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR)Oct. 1, 2017 to Oct. 31, 2017—Resolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2017 to Dec. 31, 20170.062 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2017 to Sept. 30, 20170.081 MG/LResolved
Interim Enhanced Surface Water Treatment RuleToo many readings in a month showed cloudiness above the filtration standard.EPA: Monthly Turbidity Exceed (Enhanced SWTR)April 1, 2017 to April 30, 2017—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 56 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM), uranium, haloacetic acids (HAA5), fluoride, nitrate, arsenic and chromium (total) results here are Texas’s own from 2020 on, with EPA’s national file for 2012 to 2019. Siesta Shores WCID’s own annual report, which it must send you every year, has the contaminants this page does not show.

  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.

  • What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.

  • Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; Texas’s results run from Feb. 6, 2020 to Aug. 12, 2026.

Testing your own tap

Siesta Shores WCID’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Texas certifies.

The lab Texas certifies closest to the area Siesta Shores WCID serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • City of Laredo Health Department Lab

    Laredo, TX · about 45 miles

    Certified for bacteria

    (956) 795-4908

Texas Well Owner Network, Texas A&M AgriLife Extension: Well Informed screening events, where well owners bring in water samples to be screened for common contaminants, followed by an hour-long session explaining the results. Upcoming events are on the network's calendar. Trainings, Texas Well Owner Network.

All 80 certified labs for Texas

Sources

PWSID TX2530004. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Nearby

All Texas utilities

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