"Have oil and gas companies injected toxic materials into Texas groundwater sources?
State regulators don't know, even though they agreed in 1982 to track injections into zones that could hold underground sources of drinking water, according to records obtained by The Texas Tribune.
Only now are Texas officials combing through thousands of permits issued since then in an effort to account for these injections — a revelation that has stirred concerns among environmentalists and groundwater managers.
The Railroad Commission, the state's oil and gas regulator, acknowledges in a letter that it permitted injections into at least a "handful" of zones fitting the broad legal definition of drinking water sources, but it does not know how many times that has happened over the past decades. Federal regulators have no record of approving exemptions for these injections, and in a report issued this month they instructed the Railroad Commission to prioritize gathering the data."