There has been growing concern in Frio County related to the number of Eagle Ford disposal wells located nearby. The county has the most disposal wells and the fewest number of oil wells of any major Eagle Ford county. In 2012, over 10 million barrels of waste were disposed of in the county. The number of trucks coming through the area and a growing number of disposal wells has locals a little timid when it comes to their groundwater. The Frio County Commissioners Court held a meeting in Dilley to educate locals about waste water injection.
Note: It is estimated that 20+ gallons of waste water are created for every foot of rock that is drilled. Based on that metric, Eagle Ford wells have between 5,000 and 10,000 barrels of waste each.
Groundwater is seldom to almost never contaminated by disposal wells, so the worry isn't warranted. With that, it's still important to monitor local changes to make sure the sudden increase is disposal volumes over the past few years hasn't caused any unintended changes.