This story was originally published by ProPublica.
by Nick Bowlin and Al Shaw, ProPublica — Co-published with The Frontier
Down a dirt road in northwest Oklahoma, only a few hundred yards from where the city of Enid draws its drinking water, a company injects the toxic byproduct of oil production deep underground.
That close proximity violates a state rule meant to protect public groundwater supplies from oil field wastewater, which can be saltier than the sea and laden with toxic metals. Injection operations are banned within a half-mile of public water wells unless regulators hold a hearing to ensure that such activity will not pollute the water.
But in 2018, without a hearing, state regulators approved this injection well, an apparatus that applies pressure to dispose of wastewater down a steel tube. And in the years since, the well, named the Flying Monkey, has repeatedly failed structural integrity tests, signaling a potential leak.
The Frontier and ProPublica mapped every injection well in the state to determine how close they are to public water wells. They identified at least 114 injection wells in communities across Oklahoma — including the Flying Monkey and two others in Enid — that are 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 analysis.
The city of Enid has complained to the state about the threat to its water. In Oklahoma and beyond, toxic oil field fluid has spread underground and threatened municipal supplies. Midland, Texas, is still cleaning up groundwater polluted by a leaking injection well more than two decades ago.
But Enid officials are powerless under state law to pass their own rules governing these wells. So they are appealing to the same Oklahoma agency that had approved the Flying Monkey to now revoke the permit that allows the well to inject wastewater. The city is also asking the state to impose stronger protections against pollution from injection, as more oil and gas companies seek permission to drill wells that dispose of their wastewater nearby. It’s a rare example of pushback against one of Oklahoma’s most powerful industries.
The Oklahoma Corporation Commission, which is responsible for ensuring that industry operations do not pollute groundwater, has approved thousands of orders for waivers or adjustments to state rules in recent years, according to the agency’s administrative court database. These include nearly 400 orders granting exceptions to injection regulations alone since 2022, agency records show.
The agency has repeatedly declined to punish oil and gas companies for causing widespread pollution, according to an earlier investigation by ProPublica and The Frontier. In response to that reporting, the agency told the news outlets that the state is committed to “doing the right thing, holding operators accountable, protecting Oklahoma and its resources, and providing fair and balanced regulation.”
Enid’s case will be heard in the agency’s administrative law court later this year. Ben Ezzell, a former Enid city commissioner, said he hopes the state recognizes that the community is asking for “reasonable” protections against catastrophic long-term damage to its water supplies. “It’s ultimately all one big aquifer,” he said. “You can’t just pee in part of the pool. If any of the aquifer is tainted, all of the aquifer will be tainted.”
Skirting State Laws
In 2018, a small company called Hinkle Oil & Gas applied for a permit for an injection well — the Flying Monkey — less than a quarter-mile from two of the city’s water wells. But on its application, the company had checked a box attesting that the injection well was not within a half-mile of a public water supply well — the distance that, under state rules, should have triggered a hearing to evaluate the Flying Monkey’s pollution threat. “This was demonstrably false,” Enid’s lawyers wrote in a September 2025 court filing.
The commission approved Hinkle’s application for the well without a hearing, giving the company the green light to inject more than 800,000 gallons of wastewater into the earth each day. In the last five years, the state has shut down the Flying Monkey repeatedly for failing mechanical tests required by the state that evaluate the well’s structural integrity. The well has failed five of these tests since 2021, including one in March due to a leak in the well’s tubing.
Close by the Flying Monkey, another wastewater injection well — Estill #8 — sits roughly a quarter-mile from three of Enid’s water wells and has been operating since 2012, injecting more than 12 million gallons of wastewater into the earth last year.
Enid’s Quiet Battle
Enid has become a vital source of drinking water for a dozen smaller, more rural communities as well as Vance Air Force Base. “In the 21st century, water is going to be the new gold,” Frank Baker, an Enid city commissioner, said.
Enid is asking regulators to impose a ban on oil and gas wastewater injection within a half-mile of its water wells, with no possibility of exceptions. It also wants the state to require additional testing, pollution monitoring and mechanical safety measures for wells within 1 mile of an Enid water well.
Five companies have formally opposed the city’s request for stronger rules to protect its groundwater. Matthew Allen, an attorney representing one of the companies, argued in a May procedural hearing that the city’s proposed changes would “significantly increase the regulatory burden” and costs to companies.
Enid has to bring its appeal to the state agency in large part due to a 2015 law that forbids cities and counties from establishing their own regulations on oil and gas operations. The state Supreme Court upheld the law in its 2022 decision nullifying a similar liability-insurance requirement by the city of Norman. “Municipalities no longer possess a broad police power to regulate oil and gas,” the court wrote.
Read the original story, including an interactive map of injection wells near Oklahoma drinking water supplies, at ProPublica. Sign up for Dispatches to get stories like this one as soon as they are published.