Hydraulic fracturing — using a high-pressure injection of liquid into rock to release natural gas or oil —  involves using a lot of water. Once that process is done, the fracking companies have to put that chemical-heavy wastewater somewhere.

In South Texas’ Eagle Ford — an area that has been transformed by fracking — wastewater storage units are located disproportionately in neighborhoods of color and communities with higher levels of poverty, according to a recent study. Environmental Health News reports:

After the Southwest Workers Union — where [Chavel] Lopez works as the labor coordinator — expressed concern about Eagle Ford fracking waste, [study author Jill] Johnston and colleagues looked at the racial and economic makeup of residents where oil and gas disposal wells were permitted between 2007 and 2014 in the heavily fracked Eagle Ford area of Texas. The Eagle Ford covers 26 counties and has seen explosive growth as improvements in fracking technology opened the previously untappable reserves. Researchers estimated more than 1,000 new wastewater wells have been permitted in the area since 2007.

They found that — after controlling for population density — people in areas that were more than 80 percent minority were twice as likely to live near permitted wastewater wells than areas less than 20 percent minority.

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Of the more than 217,000 minorities living less than three miles from a disposal well, 83 percent were Hispanic, according to the study published last month in the American Journal of Public Health.

Wastewater storage poses a threat of contaminating the groundwater. “A lot of people [in the Eagle Ford area] are reliant on groundwater,” Johnston told Environmental Health News. “Putting this all underground is jeopardizing water sources.”

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It’s not just water that people are concerned about. Fracking in the Eagle Ford area has greatly affected the air quality and health of the residents living there — and to make matters worse, the drilling companies face very little regulation from the state, according to a Center for Public Integrity investigation in 2014.

Similar results have been found in other states. Last year, a study found that fracking wells in Pennsylvania are disproportionately located in low-income communities.

The authors of the Texas study put their findings in context: “Throughout history, waste disposal has often resulted in environmental pollution and, consequently, harm to human health … Nationwide, a disproportionate number of waste disposal facilities are sited in communities of color, a pattern known as ‘environmental injustice.'”