Boulder City Council has authorized the city manager to pursue a state grant to help subsidize unleaded aviation fuel, marking a step toward reducing the use of leaded fuel at Boulder Municipal Airport.
While leaded gas has been banned from automobiles and most aircraft, a lead compound is still permitted for smaller, piston-engine aircraft to help prevent engine knocking. In recent years, residents, scientists and city officials have raised concerns that leaded fuel at public airports exposes nearby communities to health risks, including elevated blood lead levels, impaired cognition in children, cardiovascular illness and dementia.
The city’s application requests $63,000 from the Colorado Department of Transportation to offer a subsidy of up to $2 per gallon for unleaded avgas. Under a 2024 state law, the department has earmarked $1.5 million annually to help airports transition to unleaded aviation fuel by 2030, including Boulder’s airport.
An additional $7,000 will be matched locally from the airport fund. The cost of unleaded fuel is often higher than leaded. At Centennial Airport, which began offering unleaded fuel in 2023, officials said the price gap was $1.92 per gallon.
With council approval, the city can pursue a reimbursement agreement with a fuel provider, which will help determine a timeline for offering unleaded avgas. The current grant applies only to fuel subsidies and is expected to be awarded annually through 2030. Boulder airport’s fixed-base operator, Journey’s Aviation, is currently pursuing temporary unleaded aviation fuel infrastructure.
Once unleaded fuel is available, transition efforts will focus on increasing its use and building permanent infrastructure, which may require additional state funding. Questions remain about the airport’s long-term future, with some community members pushing to close it for housing development.
This is good news, thank you for the article. I would like to add a few relevant points that are not mentioned above.
Longmont Vance Brand Municipal airport has provided unleaded, ethanol-free MOGAS 91 octane that is usable in 75% of all the general aviation fleet with a paperwork-only STC from Peterson for a very long time. This has been in use for approximately 40 years for a lot of aircraft. Aviation applications cannot allow ethanol because it breaks down and destroys rubber in the fuel systems, which is a critical safety issue in aviation certification standards. The issue is that it is not usable in higher performance engines (high compression ratio) and it is not as stable for long term storage as avgas. The good news is this fuel is readily available and CHEAPER than 100LL and the new Swift formulation fuels, which as you point out is also not yet approved as a single fuel replacement for 100LL. As of this writing, 4/2/2026 unleaded mogas at KLMO is $0.60/gal cheaper than 100LL self serve. Nonetheless we could have moved a lot of leaded gas to using ethanol free unleaded decades ago – if we invested in additional tanks and trucks to store and use it safely and demanded ethanol free options from our local fuel distributors. This is an infrastructure issue that the city (not the FBO) should invest in while we wait for a single fuel formulation that can use to replace all the piston aviation usage, which the FAA has been working on for a very long time.
Journeys already manages the distribution of 100LL and Jet-A from city-owned and maintained airport tanks. A third fuel type or even fourth to accommodate both unleaded MOGAS as well as the forthcoming Swift 100R. Installing new large tanks would be a huge investment, but leasing or buying 1-2 new fuel trucks does not seem an insurmountable problem to me, with or without state grants. I appreciate the effort to subsidize the new fuel, but I fail to understand why we cannot have unleaded aviation gas at KBDU immediately. I have been buying it 8 miles away for almost 15 years. There’s now a station in Boulder that sells it. We don’t have to wait for a 100% perfect replacement, more expensive aviation fuel.
We can do better, and we should.
References:
https://www.globalair.com/airport/fbo-at-lmo-fly-elite-aviation-971.aspx
https://autofuelstc.com/
https://www.pure-gas.org/