Let's talk about the airport

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It’s impossible to know exactly. It will take negotiation with the FAA and possibly litigation. There may be some costs, but the land is worth more ($350 million) than reasonably foreseeable costs. Closure is doable and would not harm the city’s finances.  

The short answer is that nobody knows yet! Many communities across the United States have worked to close their local airports. Each airport’s situation is unique, so there is no easy precedent or pathway for Boulder to follow.

To close the airport, Boulder will have to end Federal Aviation Agency (FAA) control over our airport. This will require negotiation and possibly litigation. Boulder City Council has asked city staff to research and consult with expert legal counsel to better understand what it would take to close the airport.

Rumors have been floated that it will cost the city $100 million to close the airport. This rumor stems from the fact that the FAA helped the city to purchase 49 acres of land for the airport back in the 1950s and 1960s, and some have argued that the city would need to pay the FAA back for that land at market rates, which can be estimated at approximately $2 million per acre ($98 million for 49 acres).


IF we had to pay this money, it would be paid via selling 49 acres of the airport land.  Thus, the money would NOT come out of city coffers or the taxpayer pocket.

However, we don’t even know for sure that we would have to pay that amount. Some folks argue that the contracts under which that land was purchased are long expired with no expectation of any repayment, so we would owe the FAA $0 for that 49 acres. More legal research is needed to determine the truth.

However, even if the city did have to sell 49 acres of land at market rate and give the money to the FAA, the city can still zone that land for development of a neighborhood before it is sold.  And there would still be 130 acres of city owned land left that can be developed according to city priorities.

In the Repurpose Our Runways ballot initiative, the city will be required to work with current airport users and tenants on a transition to airport closure.

Some airport tenants may seek to move to another local airport. There are 10 other public airports within about 50 miles of Boulder, including 3 airports within 15 miles, which offer the same types of services and facilities as BDU. There is also a dedicated glider airport not far from Boulder, where the Colorado Soaring Association is based.

However, some may choose to sell their planes or businesses or move out of area rather than relocate locally. It's really up to those individuals. 





If BDU is closed, the remaining flight traffic would be less intrusive and less polluting because it will just be passing over. Repetitive landings and take-offs within the city limits - which cause the majority of noise and local lead pollution - would be eliminated. 

Some have argued that flight traffic from BDU “protects” the airspace over Boulder, and that if BDU closes, planes from other airports will fill in the airspace. This is a misleading and inaccurate argument. BDU attracts aviation impacts; it does not protect against them.

In addition to the small number of Boulder-based pilots who use BDU, having runways attracts planes from nearby airports to practice here, often in repetitive “touch and go” patterns where they land and take off again without stopping, repeatedly circling over Boulder homes, schools, parks, and protected wildlife habitats, trailing noise and lead pollution in their wake. 

If BDU closes, the use of airspace over Boulder would change. Without an airport to land at, flight traffic would be passing through the airspace higher up. Planes passing through at higher elevations create fewer impacts, both in terms of noise and also lead pollution, than planes flying low to the ground, taking off and landing three miles from downtown Boulder, in the middle of existing neighborhoods. 

It is also vital to understand that if the airport stays, it is expected to at least double its flight traffic in the coming years. Airport growth is the goal of the FAA, the aviation industry, BDU-based aviation businesses, and is supported by the current airport management. Boulder's airport manager has advocated for starting a new FAA Airport Master Plan update, which would be a blueprint for airport growth and development, sinking more federal money into the airport and incurring decades of obligations to the FAA.


The FAA prohibits Boulder from imposing any restrictions on aviation operations, which means we can’t ban leaded fuel or regulate noise. Voluntary measures to curb noise and lead pollution are ineffective.

The FAA message to Boulder is that we are not allowed to impose any restrictions on airport operations. This includes prohibiting us from banning leaded aviation fuel or regulating noise levels.   

Boulder has accepted millions of dollars in FAA grants over the years. We continue to seek and accept hundreds of thousands of dollars in FAA grants every few years for capital improvement projects such as repaving runways. These grants come with strings attached including giving up local control. The FAA demands include: airports must be open to take-offs and landings 24/7; we may not ban any type of aircraft operations; we must continue to sell leaded aviation fuel, even if unleaded fuel is also offered at the airport; and we cannot do anything to regulate aviation noise. The FAA only allows voluntary measures, and these voluntary measures have proven to be entirely ineffective.

Other airports are experimenting with defying these FAA mandates. It remains to be seen what the FAA might do in retaliation, such as legal challenges or fines.

Yes, this is a serious problem with serious human and wildlife health impacts. Lead dust from aviation fuel is extremely harmful. 

It can no longer be denied that lead pollution from planes is a public health and environmental crisis, despite attempts by aviation proponents to cast doubt and delay.  Not all planes use leaded fuel, but the small piston-engine planes that use BDU and other local airports still do. 

A link between regional airport traffic and the blood lead levels of children living nearby was scientifically established in the 2021 study of the impacts from Reid-Hillview airport in Santa Clara County, CA.  The peer-reviewed study found that children living downwind from the Reid-Hillview airport had higher blood lead levels, with increases of .40 micrograms per deciliter, over children living upwind from the airport. For context, lead levels detected during the peak of the Flint Water Crisis were between .35 and .45 micrograms per deciliter over baseline. 
However, Flint Michigan immediately stopped resident exposure to lead-contaminated drinking water and has since replaced the lead-lined pipes.  In contrast, exposure to lead from aviation fuel continues unabated at small airports around the United States including BDU, and there is no plan or timetable for banning leaded aviation fuel.

In October of 2023,
  the U.S. EPA issued an endangerment finding  stating that “emissions of lead from aircraft that operate on leaded fuel cause or contribute to air pollution which may reasonably be anticipated to endanger public health and welfare under the Clean Air Act.” According to the World Health Organization, “The neurological and behavioral effects of lead are believed to be irreversible. There is no known safe blood lead concentration.”

Lead testing has not yet been conducted around BDU. However, in the Rock Creek neighborhood at the west end of the Rocky Mountain Metropolitan Airport (RMMA) runway in Broomfield, only 13 miles from Boulder, residents, including an infant, have documented cases of elevated blood lead levels.

“When it comes to our children the science is clear, exposure to lead can cause irreversible and life-long health effects,” said EPA Administrator Michael S. Regan. “Aircraft that use leaded fuel are the dominant source of lead emissions to air in the country.”

95% of the lead in aviation fuel is emitted on burning, and the resulting nanoparticles are too small to be easily filtered by pollution control devices. The tiny size of these particles makes them particularly absorbable by and toxic to living tissue. Source: CDC Report "Exposures to Lead and Other Metals at an Aircraft Repair and Flight School Facility".

Lead is a known serious health risk to all animal and human life. Exposure to lead is particularly harmful to young children and pregnant women. Lead exposure can cause lifelong disadvantages for children and developing fetuses. It leads to lower IQ and has been linked to antisocial behavior as well as reproductive, heart, and other health problems.

For more information see lead in aviation fuel and aviation lead around Boulder County. ​

It will be a very long time before leaded aviation fuel is truly gone, if ever.  

The FAA currently has no plan and no timetable for phasing out or banning leaded fuel. The recent EPA endangerment finding does not compel action by the FAA. In the 25 years since lead was banned from automotive fuel, the FAA has tried and failed to provide unleaded aviation fuel, so their record is not good. And, providing unleaded fuel is not the same as phasing out leaded fuel. The truth is that unless and until there is a nationwide ban on leaded aviation fuel, some planes flying in and out of airports like ours will be burning leaded fuel over our heads.

At the time of this writing (April 2024), use of unleaded aviation fuel is purely voluntary. Our airport may be able to obtain and sell unleaded fuel, but the FAA requires BDU to also continue to sell leaded fuel. Unleaded fuel costs about $1 to $1.50 more per gallon than leaded fuel. You can imagine pulling up to the gas pump and seeing the cheap fuel next to the fuel that costs an additional $1 or more per gallon. How many pilots will choose the more expensive unleaded fuel, when many of them still deny that lead is a problem? 

At airports where unleaded fuel is currently available for small piston-engine planes, sales are low. This means nearly all planes flying in and out of small airports like ours are still buying and using leaded fuel.

What’s more, the aviation industry continues to this day to advocate for the continued use of leaded fuel because it is cheaper and available nationwide for all fleets. Any switch to unleaded fuel will be slow and incomplete for as long as leaded fuel is still an option. The aviation industry will fight fiercely against any ban. They continue to lobby Congress to ensure the continued sale of leaded aviation fuel by writing a mandate into the FAA Reauthorization Act. Here is more information about decades of past efforts around leaded aviation fuel.​

Really bad and getting worse! It’s a real and growing problem that is forcing families to move.

In otherwise quiet residential streets in Boulder, aviation noise has been measured at over 85dB, which is loud enough to cause permanent hearing loss. Planes from BDU are so loud that conversations have to stop and cars cannot be heard when crossing the street. Boulder residents have testified at City Council about wearing earplugs and noise-canceling headphones all day long in their own homes and hiding in their basements on busy airport days.

Plane traffic is at its worst when the weather is best. On beautiful days, impacted residents can’t stand to be outside in their own yards and gardens because of the extreme noise from planes constantly flying low overhead. 

Our group knows of at least seven families who have left Boulder in recent years specifically due to plane traffic from BDU. More are planning to leave. The impact is real.

Prolonged exposure to disturbing noise is known to have health impacts and can be used as torture. Long-term exposure to noise can increase inflammation and cause cardiovascular disease, hypertension, heart attacks, and other adverse health effects. Children are also more sensitive to noise, which interferes with learning.

Read more about how aircraft noise is harmful to human health. ​

BDU does not significantly contribute to emergency support operations beyond helicopters. Fire-fighting planes do not use BDU. The Repurpose Our Runways ballot initiative allows a helicopter staging area to remain at the site for emergency use only, including fire, flood, and medical emergencies. Rocky Mountain Metro Airport in Broomfield, which is 13 miles from the center of Boulder, is the hub for fire-fighting planes in our local area.

BDU’s runways are not long enough for safe use by modern fire-fighting planes. The runways cannot be lengthened since there is a lake at one end and a steep drop-off and protected farmers' ditch at the other. The only significant emergency use at the Boulder airport is as a staging area for emergency helicopters, such as those used for helicopter evacuation of stranded people and pets during the 2013 flood event. 

Boulder Airport Manager, John Kinney, told Boulder City Council on January 12, 2023, that planes that carry fire retardant are generally too big to use the Boulder Airport’s runways, and instead use Rocky Mountain Metro Airport in Broomfield that has a fire retardant dispensing and mixing station. As described in a Boulder Reporting Lab article from July 17, 2023, “air tankers, which are planes that carry suppressant to put out fires, are based at the Rocky Mountain Metropolitan Airport. [The City of Boulder’s wildland fire division chief, Brian] Oliver said the Boulder airport is useful for helicopters when fighting wildfires, but not necessary.”

In 2023, the City of Boulder developed four potential scenarios for the future of the airport site as part of the Airport Community Conversation.  Only one of these four scenarios calls for closing the airport.  This scenario, Scenario 4 “Decommission the Airport and Create New Neighborhood”, specifically states that “A portion of land would be set aside for helicopter emergency services that would support resiliency of the region” and describes that a “landing area for emergency support services” will remain on the site after redevelopment as a neighborhood. 


The upshot is good news: the City of Boulder will have helicopter emergency support no matter what happens at the airport site.

Only approximately .1% to .2% of total city sales tax revenue

According to City of Boulder sales tax revenue reports, the Boulder airport district generates only .1-.2% of Boulder’s sales tax revenue. And this district includes the businesses along Airport Road, not just the airport itself! 

Contrast that with the Table Mesa shopping center in South Boulder which has much less land (about 23.5 acres, which is about 13% of the size of the airport site). On this 23.5 acres, the shopping center has 50 tenants (about 3.5x the airport’s tenants) and generates approximately 2% of the city’s tax revenue (10-20x the tax revenue). You can see that a typical city commercial district generates much more sales tax revenue per acre than the airport! 

Proponents claim a huge economic contribution that is hugely overestimated. The claim has many sources of error such as: 

  • It is based on regional estimates that include airports much larger and busier than BDU.
  • It uses “data” that is self-reported and unverified.
  • It assumes “multipliers” based on activities that may rarely occur at BDU.  
  • It has made no attempt to do any analysis specific to BDU. 

So the actual contribution is not clear, but is almost certainly vastly overestimated.

​Airport proponents claim that BDU generates over $60 million in annual revenue. This figure, which comes from regional estimates and includes assumptions based on airports that are VERY different from ours, is too outrageous for belief. It is not backed by any analysis specific to BDU. But even if it were true, this figure would be dwarfed by the expected economic impacts of new mixed-use neighborhoods at the site. 

We are not economists, but we spotted these sources of bad data / error in the Colorado Economics Report, which is the source of  the claim that BDU generates $60 million annual revenue:

  • “Direct impacts are all estimated at regional levels.”
  • Our data region (region 3) includes Adams, Arapahoe, Boulder, Broomfield, Clear Creek, Denver, Douglas, Gilpin, and Jefferson counties/airports. Other airports in our region include much larger and busier airports, such as Rocky Mountain Metro and Centennial Airports, that have commercial transport and cargo flights, which BDU does not have. This would greatly skew any regional estimates away from the reality of what happens at BDU. 
  • The primary data for the report was generated by self-reported surveys of airport managers, airport tenants, and out-of-state visitors. There was no verification of this self-reported data, not even spot checks. The data is considered to be proprietary so it is not available for public scrutiny. 
  • Low survey response rate (e.g. 105 of 720 Colorado airport tenants responded). 
  • No survey or data was provided that matches BDU to the reported figures. 
  • “Multiplier effects” are estimated assuming that people flying into airports also stayed, ate, and otherwise spent money in the local community. No such data is available for Boulder’s airport. 
  • BDU does not have an air traffic control tower, which makes tracking “visitors” instead of local traffic nearly impossible.

Only two businesses connected to scientific research have facilities at BDU. They rarely have planes at BDU. Their planes spend most of their time flying to other parts of the country to gather data. If BDU closed, these businesses would continue to operate out of other locations.

BDU has two tenants that conduct data collection, but it would be a stretch to say that scientific research or innovation takes place at BDU or because BDU is present.

The two airport tenants with connections to research / data collection are NEON and Scientific Aviation. 


NEON, the National Ecological Observatory Network, has a hangar at BDU but does not have any planes based here. They rent their planes from another company. NEON performs regular ecological surveys of the same locations throughout the USA so that the data can be compared over time to see, for example, impacts of climate change. This is a worthy endeavor!  But NEON has over 80 sites around the United States.  They fly over Boulder twice a year to calibrate equipment. These calibration flights are particularly loud and fuel intensive, as they use dual engine Twin Otter planes that loop continuously over Boulder for an hour or more. NEON has other calibration sites, including in Greeley. If BDU closed, NEON would continue to do its research operating out of other locations.

Similarly,  Scientific Aviation has a presence at BDU. It is owned by ChampionX, a chemical and oil and gas company. ChampionX uses 1-2 planes to monitor fracking wells in Colorado and in other states such as Texas and New Mexico. They are monitoring air quality and can help identify methane leaks from the wells, among other things. Again, this is a worthy endeavor! But there are no fracking wells in the city of Boulder, so all of Scientific Aviation’s monitoring occurs in other places, and the planes are not in Boulder for most of the time. If BDU closes, Scientific Aviation will continue to do its work out of other locations.

Planes from both NEON and Scientific Aviation cause considerable noise complaints when they are in Boulder.

Yes, there have crashes, fires, and deaths.

In 2022 alone, there were six crashes and ten deaths in and around Boulder County. In one disturbing incident in 2022, a pilot associated with the Boulder Airport was filmed harassing boats over Horsetooth Reservoir before crashing.  The pilot survived and subsequently fled the country.

Did you know there is NO air traffic control at BDU, and no plans to get air traffic control in the future? It’s true! Pilots who fly in and out of BDU rely on personal visual verification that the runways are clear, in addition to using radio to communicate to other pilots their intent to take off or land. It is literally a disaster waiting to happen. In 2022, two small planes collided mid-air near Niwot, CO, just north of Boulder, killing all on board and littering debris that nearly struck Niwot High School students practicing in the school’s field nearby. Neither plane was in contact with an air traffic control, and neither was equipped with a collision avoidance system.

Shockingly, pilots of small planes (general aviation) are not required to carry liability insurance. If they crash into someone’s home or property, in addition to the risk to life safety, the property owner may be left footing the bill for clean-up and repairs. One Homeowner’s Association in Broomfield, CO is seeking $300,000 restitution for their costs to clean up from a plane that crashed into their property in 2022, including remediating lead from spilled aviation fuel. That plane nearly hit houses. 

In 2022, a plane crash in Lefthand Canyon outside of Boulder killed four people and ignited a small wildfire.  In 2014, a small plane crashed on Independence Road after taking off from Boulder Airport, killing the pilot and starting a fire.    
Read more about airplane safety and crash incidents in our area.  

The Boulder airport gets free land, utilities, and grounds maintenance from the city. The 179 acres of our public land that are currently locked up as an airport are a HUGE taxpayer subsidy to a very small number of aviation enthusiasts.

Besides the direct costs, there are also opportunity costs. The city is foregoing revenues from homes and businesses that would be located on the property if the airport weren’t there (e.g. property tax, sales tax). 


The Boulder airport gets capital improvement grant funding from the FAA and Congress via FAA Reauthorizations (taxpayer subsidies).

Boulder airport would not function without these taxpayer subsidies. The tiny amount of users and businesses located there now do not pay their own way.