Boulder Municipal Airport could begin offering unleaded aviation fuel by the end of 2026, according to a state-required transition plan that for the first time sets a timeline for moving away from leaded gas.
The move is part of a larger state and federal goal to eliminate the last remaining leaded transportation fuel, long linked to developmental harm in children and other health risks for nearby communities, by 2030. Commercial aircraft already use unleaded fuel, but most small piston-engine planes still rely on leaded gasoline. City officials say the plan will be updated at least annually as fuel technology and regulations evolve.
Boulder’s city-owned airport serves private pilots, researchers and flight instructors operating piston-engine aircraft and gliders. Dozens of homes sit within a half-mile of the airport, including the Vista Village manufactured home park and residences along 75th Street, some within 500 feet of the runway. In recent years, residents, scientists and local officials have raised concerns about lead contamination from aviation fuel, which scientists say is unsafe at any level of exposure.
A 2024 Colorado law required five airports — Boulder, Longmont/Vance Brand, Centennial, Rocky Mountain Metropolitan and Erie Municipal — to submit plans by Jan. 1, 2026, outlining how they will phase out leaded aviation fuel by 2030. While leaded gas was banned in cars in the 1990s, small aircraft still rely on it to prevent engine knocking because a universal replacement has not yet been available. The state is committing about $1.5 million a year in grants to help airports transition.
Boulder’s plan sets a goal of making retail unleaded fuel available by Dec. 31, 2026, though it does not specify what infrastructure will be required, and city officials did not provide additional details when asked. The fuel would be supplied by Journeys Aviation, the airport’s fixed base operator, which provides fueling, aircraft parking, maintenance, instruction and other services. Journeys currently operates a single fuel truck at the airport.
City spokesperson Aisha Ozaslan said transition-related costs have not been finalized, pending the scale of the project and available funding.
The plan proposes incentives to encourage pilots to switch fuels, including reimbursement for required supplemental type certification and state subsidies to offset higher costs. Longer-term plans include installing a 10,000-gallon self-service tank. Officials say infrastructure decisions will come before selecting a specific unleaded fuel type.
Elliot Dickerson, from the Soaring Society of Boulder, appreciated the fast timeline and said a surface storage tank would be an effective use of public funds. The society’s tow planes, used to launch gliders, have already been modified through the certification process to run on a 94-octane unleaded fuel, which Dickerson said is a likely option for Boulder.
“We plan to switch from 100LL (one-hundred low lead) aviation fuel to the new unleaded fuel the moment it becomes available at the airport,” Dickerson told Boulder Reporting Lab.
The transition is part of a national push led by the Federal Aviation Administration and the EAGLE initiative, short for Eliminate Aviation Gasoline Lead Emissions, which aims to end the use of leaded fuel in piston-engine aircraft by 2030. Until a full replacement is widely available, however, airports must continue offering 100LL.
A 94-octane unleaded fuel produced by Swift Fuels is already available at some airports, including in Colorado, but its lower octane can make engines more prone to knocking. Zach Gabehart, environmental manager at Centennial Airport, said at an August 2025 aviation-lead forum that some pilots reported overheating issues during summer flights and returned to leaded fuels. Centennial was the first airport in Colorado to offer unleaded avgas.
Another developer, GAMI, produces a 100-octane unleaded fuel, though Dickerson said its availability is limited in Colorado. Swift Fuels is also developing a higher-octane fuel, 100R, intended as a full replacement for 100LL. The fuel is currently undergoing certification testing by the FAA and ASTM International, and the Colorado Department of Transportation expects it could be available this year.
Debate around Boulder Airport has long focused on whether the site should be redeveloped for housing and whether federal grants require it to remain open.
Boulder ended its lawsuit against the FAA last fall after a federal judge dismissed the case, a decision that likely means the airport will continue operating for the foreseeable future, though its long-term fate remains uncertain.
More recently, attention has shifted to the health effects of airborne lead.
At the same August event, scientists, airport managers and local officials discussed research linking aviation emissions to reduced IQ, impaired cognitive development in children and increased risks of heart disease and dementia.
“As a physician, I see only one conclusion: We must urgently eliminate lead from aviation fuel,” Bruce Lanphear, a public health researcher who studies lead exposure, told event attendees.
Similar concerns have surfaced elsewhere. Reid-Hillview Airport in Santa Clara County, California, banned leaded fuel after a 2023 study of 14,000 blood samples found elevated lead levels among children living near the runway and downwind of flight paths. A 2024 Colorado study found comparable patterns near local airports.
Once unleaded fuel becomes available in Boulder, officials say the focus will shift to increasing its use, building permanent infrastructure and aligning with federal phase-out agreements.
Public feedback on the airport’s transition plan will be gathered through quarterly noise abatement meetings and tenant discussions. Residents can also submit comments through the Ask the Airport form.