Inside the City’s Water Quality Report

The City of San Angelo recently released its Water Quality Report, which details annual sampling results from various locations in town.

According to the report, San Angelo water meets or exceeds EPA requirements for most categories, but did detail three violations.

The Concho Observer wanted to answer some basic questions to better understand the rules for safe drinking water, and the nature of the violations.

How is water quality measured?

The unit that we use to measure contamination in water depends on how little is required to pose a serious health risk.

Copper content, for instance, is measured in parts per million, while lead is reported in parts per billion.

These are two very different amounts. Copper must reach concentrations that are over 1,000 times higher than lead in order to trigger what’s known as the Action Level.

Action Level (AL) is the level at which action must be taken to avoid public health and contamination risk.

What’s with the lead violation?

The city failed to provide lead testing results to a specific consumer(s) within the 30 day window required by law.

The location of the test site was not given in the report.

Due to its use in plumbing for decades, and also being naturally present in the environment, lead remains a constant problem for most municipalities.

The report from the city states that two test sites exceeded the 15-ppb Action Level. The amount the sample was above 15 ppb was not stated.  

Although there is no safe level for lead in drinking water, it’s an unfortunate reality when water is being drawn from such a large area.

In Abilene and Midland, for the last year of reported data (2023), no test sites were found with levels above the action level of 15 ppb.

For some perspective, the highest test results from the water crisis in Flint, MI were between 5,000- and 12,000-ppb. Anything over 5,000 is considered hazardous waste.

What’s with the THM violation, and what is a THM?

Trihalomethanes (THMs) are byproducts from purifying drinking water using chlorine, and byproducts in this category include chloroform.

According to the National Institute for Health, THMs at levels above the Maximum Contaminate Level (MCL) of 80 ppb, are associated with negative health effects such as cancer and adverse reproductive outcomes.

According to the city, the violation began on the July 1, 2023, and continued through December 31.

San Angelo’s range of measured samples was between 66.9 and 110 ppb. By comparison, Abilene’s highest rating was 80.6 ppb in 2023, and Midland’s was 83.8 ppb.

In December 2024, the Texas Commission on Environmental Quality (TCEQ) notified Goodfellow Air Force Base in San Angelo, Texas, that its drinking water system exceeded the limit for TTHM’s (Total THM’s), which reported a level of 84 ppb for THM, exceeding the EPA standard of 80 ppb. 

What’s with the public notification violation

From the report: “We failed to adequately notify you, our drinking water consumers, about a violation of the drinking water regulations.”

The violation began Sept. 22, 2024, and continued to Nov. 21.

While the violation notice does not list a specific violation, the dates coincide with the THM violation dates.

These notices are designed to alert consumers there were a serious problem with their drinking water, which would require a boil water notice or other measures to be taken.

What can we do about THMs at home?

The EPA advises that boiling water for one minute can reduce THM levels by up to 75%. Carbon filters (like those in pitcher or faucet-mounted filters) can effectively remove THMs. Reducing the time spent in hot showers or baths can also help limit inhalation of THM’s

What was the cause of this increased contamination?

Any presence of organic matter in the system can lead to the formation of THM’s  

One of the possible causes for the increase in THMs is due to the City’s groundwater plant being offline for upgrades over the last year, as groundwater has a lower level of THMs than surface water. 

The City of San Angelo reported in March 2025 that THM levels in the public water supply had dropped significantly, falling below the regulatory limit. Attributed to the renewed use of groundwater from the Hickory Aquifer.

Per the City of San Angelo’s website, they have brought their groundwater treatment facility online as of 21 November 2024. 

It is expected that THMs will be reduced back to safe levels, as per EPA regulations.

Are there other things we should be worried about?

Haloacetic Acids are another byproduct of water treatment.

For this chemical group, 60 ppb is the limit, and the city’s report lists 13-37.1 ppb as the range of individual samples.

These compounds seem to pose similar risks as THM’s, such as reproductive harm and possible cancer risks.

Where does our water come from?

The City of San Angelo can draw upon both O.H. Ivie Reservoir and the Hickory Aquifer, with contracts that authorize a combined 30,000 acre feet of water per year, or over 9.7 billion gallons.

How much water do we use?

Last year, 4.9 billion gallons of water was treated at the San Angelo plant. This is around 135 gallons per person/per day.

This includes commercial use of water, and merely reflects the scale of the consumption, not necessarily the water use of the average San Angeloan.

Why does the city flush the fire hydrants?

Routine flushing removes concentrations of residual chlorine in the system to prevent unsafe amounts of by-products like THM’s and Haloacetic Acids.

Flushing is also used to regulate water main pressures and prevent breakages in aging cast iron pipe.

Though it may seem wasteful to pour drinking water down the street, it prevents much larger problems with the system, accounting for 0.7 percent of the total water treated in 2024, or around 34 million gallons.

How can I do my own research?

Annual water reports are available for San Angelo and other cities in the area in the links provided below.

https://www.sanangelo.gov/ArchiveCenter/ViewFile/Item/219

https://www.midlandtexas.gov/ArchiveCenter/ViewFile/Item/272

https://abilenetx.gov/waterqualityreport

EPA guidelines and regulations are available directly from the agency through their website: www.epa.gov