Extreme rainfall exacerbates contamination in Texas waters, new study finds

Feature story published on Reporting Texas on May 16, 2025.

During hot summer days in Lake Jackson, Texas, an unofficial splash pad was a community favorite. Kids dodged the sudden bursts of water shooting up from the ground, letting the spurting fountain playfully hit their faces. 

But at the end of August 2020, 6-year-old Josiah McIntyre played there for the last time.

“He started off with a headache, which was odd because he never really complained of headaches before,” said his mother, Maria Elena Castillo. 

Within days, Josiah’s symptoms worsened: flu-like fatigue, confusion, a sudden loss of balance. At Texas Children’s Hospital in Houston, a lab technician discovered Naegleria fowleri, a deadly amoeba that thrives in warm freshwater and enters through the nose, in Josiah’s brain. The boy passed away less than a week later.

“It went from thinking that he just had this viral infection that I was told about the day before, to ‘you need to be prepared to not leave here with your child’” Castillo said. 

With a 3% survival rate, Naegleria fowleri infections are rare, affecting fewer than 10 people in the U.S. annually, according to the Centers for Disease Control and Prevention (CDC). But Josiah’s case highlights a larger, systemic issue. Water contamination is an increasing risk across Texas, and some communities face a much greater threat than others.

New research published in the January issue of the journal of the Science of The Total Environment revealed that extreme rainfall events caused by climate change increase the risk of water contamination, particularly in disadvantaged communities. Researchers found that how and where rain falls in Texas directly affects water quality, leading to spikes in bacteria such as E. coli.

“We should focus on these disproportionate impacts in different regions, for different communities and in different seasons,” said Xiofeng Liu, study author and AI-in-science specialist.

In Josiah’s case, the CDC traced the amoeba to the splash pad he had visited with his grandparents the previous week.

 “There was a gap in the system,” said Castillo, referencing how the facility lacked proper chlorine levels to filter harmful pathogens. 

Infrastructure failures are only part of the problem. Extreme weather patterns both spread and intensify contamination, making it even more difficult to control.

“The most important dynamic process is surface runoff,” said Chen Zou, a landscape researcher and co-author of the study. “With climate change, we know that it is not just the extreme precipitation, but also the temperature and annual facilitation that are becoming high.”

Facilitation refers to the environmental conditions that allow bacteria to flourish. In Texas, two key climate-driven factors contribute to such processes. 

First, heavy rainfall flushes contaminants from soil, sewers and agriculture into water bodies such as ponds and creeks. South Texas experiences seasonal monsoon-driven risks, while Northeast Texas faces year-round threats due to its wetland density.

“We happen to find that there’s a positive relationship between the extreme rate of impact and the wetland percentage,” Liu said. “The wetland can be both a sink and a source of the E. coli.”

Second, prolonged droughts allow bacteria to accumulate in stagnant water, increasing the risk of rapid spreading once the rain returns. 

Researchers classify water bodies as “impaired” when contamination makes it unsafe for drinking, recreation or aquatic life. Texas has 1,051 impaired water bodies, nearly a third with elevated bacteria levels, according to the Texas Commission on Environmental Quality. That means one in every 20 water sources in the state is compromised.

The risk is highest in underfunded communities prone to runoff, where water quality is often untested. Government agencies acknowledge the risks but say limited resources constrain more proactive action.

“The cities or counties we’re talking to, they want to do more,” said Lucas Gregory, associate director of the Texas Water Resources Institute. “They just don’t have the funding to do it, or the staff capacity to do additional things.”

While the institute helps local governments develop watershed protection plans, implementation remains a challenge. Grants from the Environmental Protection Agency (EPA) through the Clean Water Act and funding from the Texas General Land Office offer some financial support, but competition for resources is high.

The stakes become clear during disasters. Last year, Hurricane Beryl triggered boil water notices across Harris County as wastewater, fertilizer and manure overflowed into reservoirs. The county also sued a wastewater treatment facility last month after discovering E. coli levels in Crosby waterways were 1,000 times the legal limit.

Crosby is only an hour from Lake Jackson, where Josiah died. After his death, Governor Greg Abbott declared a disaster in Brazoria County. But warnings like these often come too late for residents to take action, forcing them to take matters into their own hands. 

“I take chlorine strips wherever we go, and I make sure that levels are clean,” Castillo said.

Not all E. coli strains are dangerous, but the study classifies their presence as a primary indicator of contamination risk. Researchers hope the 21 years of data will help Texas policymakers create specific early-warning systems and response plans.

“We hope this kind of scientific finding can give agencies like the EPA or local environments some hints,” Liu said. 

Their goal is to develop an interactive land-use planning tool to help policymakers proactively manage contamination risks based on environmental, infrastructural and socioeconomic factors.

“We definitely need to understand how that pollution happens,” Liu said. “The stakeholders really need the data to inform their policy, to inform their actions.”

Meanwhile, families like Josiah’s stay vigilant.

Josiah was a huge baseball fan, and his family now runs a foundation that raises awareness about amoeba infections. Each year, they host a home-run derby to fund scholarships and distribute free nose plugs to prevent exposure when swimming in untreated freshwaters.

“There’s no way to stop yourself from contracting it,” Castillo said. “But there are ways to prevent it, and that prevention starts with the nose plugs.”