A festering conflict between Adams and Denver counties over how Denver International Airport should develop has threatened to destroy years of harmonious regional cooperation and send both counties into court.

Lawyers for the two counties are lining up, stern e-mails have flown back and forth, and talks have broken off and then restarted amid threats of litigation.

A key meeting last week between leaders in both counties — which was closed to the media and public — appeared to be the first step toward getting the two sides working together on an issue that has vexed them for nearly a year and in some ways has been an ongoing battle between the two counties for decades.

“You think it’s frosty now? I don’t think there will be any trust left in the region if this happens,” said Adams County Commissioner Erik Hansen, explaining his county’s disagreement over Denver’s plans to develop DIA.

The key point of difference is over millions of dollars in future income that could be generated on airport property. Adams County fears that industries will flock to locate on the airport, bypassing their communities.

Adams County officials want Denver to legally justify creating an “Airport City” on vacant DIA property — an idea that Adams officials say violates a 25-year-old intergovernmental agreement between the two counties on how the airport should develop.

“(Denver’s) posture now is nothing violates the IGA,” Hansen said. “That’s an interesting posture, but that’s not very productive. There has to be a recognition of the historical issues and what happened in order to address the concerns of the region.”

Adams and Denver have been the Hatfields and McCoys of Colorado counties when it comes to land issues — bordering jurisdictions that have a history of squabbles dating back to the 1960s.

In those disputes, Denver has been portrayed as the big bully and Adams County as the dumping ground.

They have wrestled over airport noise, a proposal to expand the old Stapleton airport into Adams County and the creation of DIA.

There was even a dust-up when Denver built a sewage-treatment plant across Adams County’s border that did not accept waste from Adams County — perpetuating the notion that Denver sees Adams as a dumping ground.

Now, with DIA’s $500 million South Terminal construction project underway that will add a commuter-rail station by 2016 and a 519-room hotel by 2015 — Denver believes the airport is ripe for further expansion.

Denver Mayor Michael Hancock’s top priority is developing the airport and the land around it, a concept he says will “create Denver’s tomorrow” and “pay dividends for our community and our children for decades to come.”

Adams County officials say Hancock has conjured these plans with complete disregard for the communities around the airport and has dismissed binding agreements signed decades ago to make sure Adams didn’t lose out when and if an economic boom at DIA occurs.

“There is a price here, and that is the economic development of a really major airport,” said Allan Wallis, associate professor at the University of Colorado Denver, who has studied this issue for years. “It is not at all surprising that they would resurrect those hostilities.”

“Aerotropolis” idea

DIA now appears to be at the threshold of such a boom, and Denver is busy planning how to handle it.

Hancock wants to build an “Airport City” on DIA land as part of a larger region-wide “Aerotropolis.”

In 2011, the city spent nearly $1 million for a consultant to prepare a comprehensive land-use plan designed to increase commercial development on airport property.

DIA has hired outside firms to create logos to promote the Airport City concept and introduced the idea last year at the annual Airport Cities World Conference that was held in Denver.

“We have a unique opportunity to take our region’s biggest economic engine and spark a new era of growth that will transform metro Denver and revitalize the regional economy,” Hancock said in his conference speech. “We will create a development that thrives on the airport’s natural synergy, attracting business and jobs that benefit from a close relationship to the airport and its inherent access to national and international markets.”

Airport City would be home to aerospace, bioscience and other industries located in clusters on about 9,000 acres of unused land on the 53-square-mile airport property. Over the next two decades, Airport City could add 30,000 permanent jobs and create more than $300 million in tax revenue.

Hancock is careful to say the plans are not anything more than concepts at this point.

“We are not going to build speculative structures and hope someone comes,” Denver Airport Manager Kim Day said at a recent meeting with Aurora leaders. “What we are going to do is plan — plan so that we can make strategic decisions when opportunity presents itself.”

Those plans, however, don’t sit well with Adams County officials — who include Adams County commissioners and the mayors of Aurora, Brighton and Commerce City.

In July, they sent Hancock a letter claiming his Airport City concept violates the 1988 agreement between the two counties. The two factions met in August and released a joint statement that said they are working toward consensus on the issue.

But that soon disintegrated.

The next month, Adams County officials sent Denver a formal request, citing Colorado’s Open Records Law, demanding to see the city’s development plans, financial records and contracts with outside firms hired to develop the airport.

That inquiry upset Denver.

The “request is unprecedented from one governmental entity to another and a bad choice amongst neighbors and friends,” said Denver City Attorney Doug Friednash in an e-mail to Adams County Attorney Jen Wascak obtained by The Denver Post. “There are better, more productive ways for us to do business. … I am hoping that this is not a sign of things to come from Adams County. Let’s dial this back, okay?”

Further meetings between the two sides were canceled.

Mutual economic benefit

The crux of the conflict, as it usually is, is about money.

The IGA signed by mayors, commissioners and other officials in 1988 was drawn up to address a wide spectrum of issues that could result from the construction of a large new airport — ranging from zoning issues, noise regulation and runway configuration to the number of hotel rooms Denver could build on the site.

An underlying theme of the IGA was that any future economic benefit should help “both communities and the region as a whole.”

The agreement was penned and signed but also required Adams County residents’ vote to approve Denver’s annexation of 53 square miles of Adams County to build the airport.

The document was years in the making. Paragraphs were written and rewritten and maps were drawn and redrawn until everyone from both counties was satisfied.

“We were intent on trying to get every word in place to protect the interest of voters in Adams County,” said David Busby, a former Commerce City mayor who sat in on the last years of negotiations.

The IGA limited what Denver could build at the airport to “only those land uses which are accessory uses” — defined as “necessary for or directly related to the operation of the new airport.”

That included “manufacturing or other commercial activities which by customary practice require direct airside access.”

“We didn’t want to limit the airport, and we didn’t want Adams County people to think it would have a disproportionate advantage. We were trying to find the balance,” said Tom Gougeon, who was an assistant to Denver Mayor Federico Peña and one of the key players in drafting the agreement.

“We did the thing we could do, a guiding principle,” said Gougeon, now president of the Gates Family Foundation and a Denver Water Board commissioner. “If it has a reasonable relationship to aviation, then it can be here. If it doesn’t, it can’t. We didn’t go beyond that. Obviously, there is room for interpretation. We didn’t try to make a list. We wanted to give people a premise and let them figure it out.”

Steve Cramer — a former Adams County commissioner who negotiated and signed the agreement with Denver — said it appears that Denver’s Airport City plans violate that agreement. But he said there’s no reason the two counties couldn’t reach common ground to ensure that both benefit equally from any new development.

Skip Spensley, who headed Denver’s new airport office at the time, said the IGA was aimed at ensuring that both counties profited from the massive economic engine that the airport would become. DIA is now the nation’s fifth-busiest airport.

“This was not a land grab by Denver for economic development,” Spensley said. “The IGA was so Denver would retain revenues from aviation development. Off the airport land, outside the boundaries, the intent was Adams would get the economic benefit.”

The IGA was signed one month before Adams County residents voted to allow Denver to annex the Adams County property for the airport.

Gov. Roy Romer spent weeks going from diner to diner on his “oatmeal circuit” to woo Adams County voters into approving the annexation.

Now, Adams County officials wonder if those votes meant anything.

“Promises were made face to face with a handshake,” Adams County Commissioner Eva Henry said in a meeting with The Denver Post. “Our voters voted in favor of trusting Denver and that they would honor those promises and the IGA.

“What this is doing is threatening our regional coordination that could not only threaten Airport City. This is also threatening regional cooperation that they will need to bring in events like the Super Bowl and the Olympics. Hancock needs to come to the table and have a conversation with us. Denver needs to acknowledge that the IGA needs to be enforced.”

Hancock said late last year that he was shocked by the opposition.

“What hit me, literally, like a left fist, it hit me hard, I just did not see it coming, were these concerns that were based on 25-year-old history,” Hancock said in an interview with The Denver Post.

“We spent a lot of time talking about them, and we couldn’t get them to understand this is about visioning; this is about growing this area and about 30,000 to 40,000 jobs that we can work cooperatively to bring to this area,” he said. “It’s hard for me to stay in the weeds when I want to fly at a different altitude.”

Finding common ground

Last week, leaders from Denver and Adams County met for two hours, trying to work through the issues.

“It’s a new day,” said Adams County Commissioner Charles “Chaz” Tedesco after the meeting.

A joint statement released after the closed-door meeting conveyed the notion that the two sides had found common ground and were now willing to work together to pursue “regional economic opportunities surrounding Denver International Airport. … Only together will our region win. Future discussions will focus on issues that uplift us all.”

Most people involved in forging the original agreement in the 1980s said that’s exactly what should happen.

“This is a perfect opportunity for Denver and Adams to work together for their mutual benefit,” said Spensley, the former head of the new airport office who now teaches at the University of Denver. “They ought to sit down and figure out, ‘How can we maximize the airport?’ Let’s get everyone in the same room. Let’s talk about how we can make this work for everyone. We each have things to bring to the table. Adams County has land to develop, and Denver has an airport. There is a way to make the pie bigger for both.”

Gougeon, who helped broker the deal between Adams and Denver in 1988, said the two sides are probably closer to agreement than they realize.

“It’s hard for me not to think there is a solvable problem there if there is a problem really at all,” Gougeon said. “They are still better off to continue to work together and do good planning for what kinds of land uses ultimately end up happening on or around the airport. That’s really what matters. Who gets what is not important over, ‘Do you do a good job or make a mess of it?’ “

Jeremy P. Meyer: 303-954-1367, jpmeyer@denverpost.com or twitter.com/jpmeyerdpost

Yesenia Robles: 303-954-1372, yrobles@denverpost.com or twitter.com/yeseniarobles

What is airport city?

The proposal would include 9,000 acres of land on the 53-square-mile Denver International Airport property and be developed as a home to aerospace, bioscience and other industries in clusters. Proponents say that, over the next two decades, Airport City would generate 30,000 permanent jobs and more than $300 million in tax revenue.