Owner plugs Enid disposal well after investigation reveals permit violations

Statewide, 114 injection wells sit within a half-mile of public water supplies

On Sept. 14, employees of BCE-Mach III Midstream Holdings LLC dropped a cast iron plug into the bottom of the Flying Monkey disposal well, followed by more than 200 sacks of cement, permanently sealing the well, according to a report the company filed with the Oklahoma Corporation Commission. A representative of the state was on site to witness the plugging. The well, which injected oil field wastewater underground, sat roughly a quarter-mile from two municipal groundwater supply sites serving the city of Enid in northwest Oklahoma.

The closure followed a Frontier and ProPublica investigation that found the Corporation Commission had approved the well in 2018 in violation of a state rule. Oklahoma rules bar wastewater injection within a half-mile of public water wells unless regulators hold a hearing to ensure the activity will not pollute groundwater. The Corporation Commission did not hold a hearing before approving the Flying Monkey.

Eric Huddleston, an attorney representing BCE-Mach III Midstream Holdings, which acquired the Flying Monkey in 2020, said the company decided to permanently shut the well after determining it was “underutilized and operationally unnecessary.” A spokesperson for the Corporation Commission did not respond to requests for comment, including about the agency’s role in the well’s closure.

Enid city officials said they did not know the well had been plugged until a reporter informed them. “This decision is, for lack of a better word, thrilling because this is such a vital issue,” said Frank Baker, an Enid city commissioner. “Our water sources have been put in danger, and for this one well to have been plugged, this is the best possible outcome.”

The city of Enid filed a complaint in 2025 asking the state to revoke the Flying Monkey’s permit to operate. In that complaint, Enid’s lawyers noted that the well’s original operator, Hinkle Oil & Gas, had incorrectly checked a box on its permit application stating that the injection well was not within a half-mile of a public water supply well. “This was demonstrably false,” Enid’s lawyers wrote. Hinkle previously declined to answer questions about the Flying Monkey.

Earlier this year, BCE-Mach III Midstream Holdings refiled a permit application for the Flying Monkey in which it acknowledged the proximity of the city’s water supply wells.

The Flying Monkey had a troubled operational history. State regulators shut the well down repeatedly in the last five years after it failed tests of its structural integrity. These failures can indicate a problem that might allow wastewater to escape, potentially threatening drinking water sources. The well failed five of these tests since 2021.

In early July, nine days after the newsrooms’ investigation published, the Flying Monkey’s owner reported another leak in the well’s tubing. The state gave BCE-Mach III Midstream Holdings 90 days to fix the leak or to permanently plug the well.

The investigation identified two other wells in Enid that violated the state distance rule between wastewater injection wells and the city’s groundwater supply sites. Both wells, which are owned by other companies, remain active.

Across Oklahoma, the news outlets identified at least 114 injection wells located within a half-mile of a public water supply well. More than 300,000 Oklahomans live in communities that rely on these water wells, according to the newsrooms’ analysis.

Baker, the Enid official, told The Frontier and ProPublica that he hopes the Corporation Commission will begin to plug other injection wells that threaten public water supplies. “I hope and pray this is an example that we’ll start to see replicated across the state in the near future,” he said.

In addition to its request to plug the well, the city of Enid has asked the Corporation Commission to impose stronger regulations on oilfield wastewater disposal near its water supply, including a wider distance buffer between the injection sites and the city’s water wells. The request comes amid a recent uptick in wastewater injection in the Enid area, according to a legal filing made by the city. The Corporation Commission previously declined to comment on Enid’s complaint because it is an active case. The case will continue to be heard in the agency’s administrative law court later this year.