In 2024, a team of scientists from Texas A&M released a first-of-its-kind study that confirmed something many Rio Grande Valley residents have feared for years: toxic chemicals are present in the Arroyo Colorado — and we’re being exposed to them.
These chemicals are called PFAS — short for per- and polyfluoroalkyl substances. They’re man-made chemicals used in everyday products like nonstick pans, water-resistant clothing, food packaging, makeup, and firefighting foam. The problem is, PFAS don’t break down in the environment — which is why they’re also called “forever chemicals.”
🔍 What Did the Study Find?
Researchers tested 30 PFAS chemicals in water samples across the Arroyo Colorado watershed — a river system that stretches through Cameron, Hidalgo, and Willacy counties. They tested irrigation canals, stormwater ponds, wastewater, and even local drinking water.
14 different PFAS were found in the Arroyo Colorado.
95% of the samples tested positive for PFAS.
The highest contamination came from areas near airports and wastewater plants, especially south of the McAllen airport.
Some drinking water samples also contained PFAS — below EPA limits, but still detectable.
Why Does This Matter?
PFAS exposure has been linked to:
Cancer (including kidney and liver cancers)
Hormonal problems
Low birth weight and birth defects
Weakened immune systems
Developmental delays in children
Short-chain PFAS — the kind found in most RGV samples — are easily absorbed by plants, meaning they could end up in crops grown with irrigation water from the Arroyo.
Is Our Water Safe?
Even though levels found in drinking water were technically “within current federal limits,” the study points out that many of the PFAS found are not yet regulated, and science continues to evolve on how dangerous these chemicals really are. The fact that PFAS are already showing up in municipal water and private wells is a warning sign.
Where Is This Water Going?
The Arroyo Colorado is used for irrigation, storm drainage, and wastewater discharge. It runs through colonias, farm fields, and neighborhoods where tens of thousands of families live and work. And because many residents don’t have access to centralized water systems, they rely on private wells or haul drinking water — often unaware of what’s in it.
How Does the Valley Compare?
In some areas, PFAS levels in the Arroyo Colorado were higher than those found in rivers near chemical plants in Europe and Canada. That’s despite the Valley having no large-scale PFAS manufacturers — which makes the contamination even more concerning, as it’s likely coming from airport foam, wastewater runoff, and local industries.
What Needs to Happen Now?
This study is a wake-up call. It shows that:
PFAS are already in our environment
We’re being exposed through water and possibly food
Communities in the RGV deserve immediate testing, cleanup, and transparency
And yet — this is only the beginning. The researchers call for more studies to test local crops, groundwater, and long-term exposure in families.
Bottom Line:
The Arroyo Colorado is contaminated. PFAS are here. And the public needs to know.
This isn’t just a science issue — it’s a human rights issue. Clean water is a basic right. And everyone in the Rio Grande Valley deserves to live without fear of what’s coming out of their tap or into their soil.
Read the full study here.
https://ucowr.org/wp-content/uploads/2024/06/Liu_et_al_180.pdf