Colorado is currently cleaning up almost 1,000 old oil and gas wells left behind by operators unable or unwilling to cover the costs and effort. Its already a big, expensive job, but the backlog of so-called orphan wells may soon grow.Denver7 Investigates found that thousands of low-producing wells, still on the books as active, are nearing the end of production and teetering on the edge of becoming the states responsibility. These older wells are more expensive to maintain and have slimmer profit margins, often leading to leaks and spills from aging equipment, with risks to health and the environment.Many of these low-producing wells are scattered around the Front Range, often near homes, farms and schools.To uncover the potential threats posed by old, unplugged wells, Denver7 Investigates partnered with ABC News Investigates and local news stations across the country. This nationwide investigation, Zombie Wells: The Threat Beneath, tested a total of 76 wells across five states and found that more than half were leaking oil or combustible gas at the time. Denver7 Investigates went out to more than a dozen well locations in northern Colorado to check for leaks. We were equipped with a handheld gas detector and a safety device that monitors ambient air quality. These devices can detect hundreds of combustible gases, including climate-warming methane.We tested some wells known as orphans deserted by their operators, leaving the state to clean them up. At these well locations, which are already under Colorados care, we did not find any emissions detected by our monitors.But when we visited low-producing wells, we found potential problems. When an old oil well starts leaking toxic fumes or climate-warming pollution, you usually cant smell or see it. Monitors like the ones we used cant always detect the gases either if its windy and the device isn't close enough, the emissions can dissipate quickly.Thats when a specialized infrared camera can reveal emissions. We tested roughly half a dozen well locations with a certified optical gas imaging thermographer an expert trained to document pollution from oil and gas operations using industry-grade technology. Andrew Klooster operates a forward-looking infrared (FLIR) camera as a Colorado field advocate with the environmental nonprofit Earthworks. With his camera and our detectors, we headed to the small town of Frederick in northern Colorado.Frederick is just 15 square miles wide, but hundreds of old oil wells dot the landscape.We stopped by a set of four wells in a field near a school. Overgrown weeds, birds nests tucked into pump jacks and rusted equipment showed us what state records confirm: in the last year, these wells produced a combined total of less than one barrel of oil per day. As the years go on, if they don't get plugged and they don't get taken care of the potential for a leak to occur just goes up, Klooster said.During our visit in late June, Klooster filmed potential emissions leaks coming from equipment on two of the wells. We also saw what appeared to be a historic spill a dried-up puddle of jet-black petroleum with clumps in the field outside of the fenced-in well pad. WATCH: Infrared camera shows potential emissions leak coming from equipment on wellKlooster reported these potential problems in July to Colorados oversight agency, the Energy and Carbon Management Commission (ECMC).A state inspector went to the well site in late August and saw compliance issues they plan to follow up on, including overgrown vegetation and inaccurate, faded signs. The inspection report didnt mention any possible leaks or spills.The state oversight commission said it inspects wells on average every 1.7 years. However, a Denver7 review of state records shows that inspectors only dropped by this location every three to four years. The wells are less than 500 feet from Frederick High Schools outdoor sports fields. The St. Vrain Valley School District told Denver7 theyve never heard from the operator about any potential concerns. However, the district complies with all state and federal rules and regulations regarding the safety and well-being of students and staff. The district said it is also taking the additional preventative measure of monitoring the ambient air quality throughout the school and testing for the presence of methane. That monitoring has not detected any air quality concerns within the building, the district said. Denver7 also contacted the operator of the wells, KP Kauffman, also known as KPK. The company said it reviewed Kloosters complaints and after checking all equipment, determined that the wells and all components are functioning properly. KPK believes the infrared video shows heat radiating from black process piping," not emissions leaks.Still, Klooster said when oil well sites like this get older, they can easily fall into a state of disrepair and become a potential source of emissions until they're taken care of, until they're cleaned up.If you think of all the hundreds, if not thousands, of facilities that are quite like this, it all adds up, he said.KPK alone is operating more than a thousand low-producing wells in Colorado. Colorados commission overseeing oil and gas considers KPK an operator with the highest risk of orphaning their wells. Thats because old wells are more expensive to maintain and have slimmer profit margins. Once theyre totally depleted, the state worries KPK will be unwilling or unable to plug them. KPK told Denver7 it strongly disagrees and accuses the commission of unlawfully using its police power in a coordinated attempt to put this longstanding company out of business.KPK said it fully intends to meet its plugging and abandonment obligations and is better suited to perform that work than the [states] Orphaned Well Program and even most other operators because it owns a subsidiary well service company.Nonetheless, the state commission has continuously raised concerns in recent years about KPKs willingness or capacity to follow regulations. Colorado put its trust in this operator that they would change their legacy culture of non-compliance, Commissioner John Messner said in a February 2023 hearing. Unfortunately, this is a case of fool me once shame on you, fool me twice shame on me. This commissioner will not be fooled twice."In the last 10 years, Coloradans living and working near KPK wells have filed complaints with the state almost 200 times.A few years ago, the U.S. Environmental Protection Agency settled a lawsuit against KPK for alleged violations of the federal Clean Air Act and Colorado air quality regulations. Colorados commissioners have repeatedly cited KPK for dozens of violations, including spills, leaks and unkempt well locations. Following several enforcement cases since 2022, the commission ordered the company to pay more than $2 million in penalty fines. The commission told Denver7 it has also issued 47 new notices of alleged violations to KPK, which are still moving through the enforcement process. "Staff continues to inspect and document conditions at KPK facilities and spill locations and will take additional enforcement action as necessary," the commission said.Late last year, the commission also ordered KPK to pay out a total of roughly $133 million in bonds over the next 10 years to cover the future costs of cleaning up their wells. Its a process called financial assurance, which Colorado recently overhauled to ensure operators are setting aside enough funds to properly plug their wells and return the land to its condition before oil and gas operations.KPK hasnt paid. Instead, the operator has filed two ongoing lawsuits against the state, which argue the commissions rulings were arbitrary and capricious.KPK said the commission has artificially manufactured the risk of the company not cleaning up its wells through death-knell sanctions and selective enforcement against KPK. KPK's lawyer John Jacus provided Denver7 with a copy of a complaint letter the company sent last week to the U.S. Department of Interior requesting that its Office of Inspector General launch an investigation into alleged "malfeasance" by Colorado's Orphan Well Program.Colorado's Energy and Carbon Management Commission said, "KPK has a history of serious and ongoing non-compliance with state law and ECMC rules. ECMC denies KPKs baseless allegations of malfeasance and will continue to do everything that we can to ensure that KPK lives up to its obligations to the people of Colorado."When it comes to KPK's refusal to pay the state fines and financial assurance, the company told Denver7 doing so would bankrupt them, orphaning their wells and making the clean-up the responsibility of Colorado taxpayers. But former Colorado State Representative and Senator Michael Foote said that rings a little bit hollow.This is a best business practice for them to put forth money to clean up their mess at the end of the day, Foote said. When they're not doing it, they're kind of cheating the system.Foote is one of the lawmakers who helped shift the states mission from fostering the oil and gas industry to regulating it.The plan was to be more protective, he said. Many people knew that it was already a problem and it was likely to get worse. But state regulators are now facing a Catch-22. Since low-producing wells arent very profitable, those operators may not have the money to maintain them. And that poses a real problem for public health, safety and welfare, Foote said.But when the state orders those operators to pay for fixes and cleanup, they just aren't doing it. Maybe they can't. Maybe they just don't want to. But they're resisting the order to do it, Foote said.In the future, it would be better to try to identify companies that would be like KP Kaufman and see if [the state] can intervene a little bit sooner, he continued.Colorado is taking some new steps to deal with low-producing wells. The state plans to start plugging low-producing wells, with support from a $12.6 million federal grant. Colorado will prioritize cleaning up old wells located close to disproportionately impacted communities and those known to be high emitters of climate-warming methane.Low-producing wells account for up to half of all the pollution released by the states oil and gas industry, according to a recent Colorado State University study.Colorado estimates the cost of cleaning up one well to be more than $100,000. So, this program could cover roughly 120 wells.With potentially thousands of these low-producing wells reaching the end of their production in Colorado, itll take time and a lot more money for the state to clean them all up.