Here is some relevant history regarding Boulder Airport.
For decades, FAA grant obligations included a 20 year commitment to operate the airport. Boulder took its last grant in 2020, obligating the city through 2040.
The City reports that the average FAA grant is about $250K per year. https://bouldercolorado.gov/news/fast-facts-about-future-boulders-airport-site
The ANC collected over 3400 valid signatures of city residents asking that the future of the airport be decided by voters, qualifying to appear on the November ballot. The campaign collected more than the number of signatures required to get on the ballot in the short time window available. Meeting this threshold is a clear signal that the people of Boulder want to vote on this issue.
In an attempt at intimidation, the FAA contacted Boulder City Council asserting its opinion that Boulder is obligated to operate the airport forever, unless released by the FAA. The FAA “explained that it will only consider releasing an airport sponsor . . . where this is a net benefit to civil aviation” and that “it would not consider the closure of the Airport to benefit civil aviation.”
History shows that the FAA only releases airports (in other words, allows the airport to be decommissioned) under extreme circumstances such as:
Litigation, which was the case for Santa Monica Airport
An act of Congress that requires them to do so, as with Banning Airport in California
When an entirely new replacement airport is built, such as Stapleton Airport which was replaced by Denver International Airport, and Mueller Airport which was replaced by Austin–Bergstrom International Airport.
While all parties agree that the city is obligated to operate the airport through 2040, the city disagreed about the perpetuity obligation. No language in either of the relevant contracts signed in 195x or 197x indicate any such obligation. This is a retroactive interpretation of the contract language.
Consequently Boulder sued the FAA to clarify whether the city's obligations to the FAA end in 2040 (as the city maintains) or whether the city is obligated to run the airport in perpetuity (as the FAA claims). https://law.justia.com/cases/federal/district-courts/colorado/codce/1:2024cv02057/235919/38/