The celebration in Boston on Wednesday featured all the party favors you could hope for on your special day: balloons, glittery cone hats, and a vanilla-frosted cake topped with sugary decorations.
But not a match to light the candles for the cake was in sight.
That’s because the tongue-in-cheek festivities were a jab at utility companies for allowing a gas leak in the area to persist for 30 years, a milestone it marked this week.
“It’s been there since the Bee Gees,” said Audrey Schulman, president of the Home Energy Efficiency Team, or HEET, a nonprofit based in Cambridge. “That’s a long, long, time ago. And that’s unfair.”
Members of Clean Water Action, Mothers Out Front, Boston Climate Action Network, and the Massachusetts Sierra Club joined Schulman at the event, which was held to build awareness about gas leaks ahead of a City Council hearing on the topic scheduled for Monday.
Activists made public in August detailed maps of leaks around the state that they had created using data from utility companies. The companies are required by state law to pinpoint locations of known leaks and how long they have been there. They’re also required to immediately repair ones that pose risks of explosion.
Activists say the leaks are wasteful, environmentally hazardous — and potentially dangerous.
“It’s bad for health, it’s bad for trees, it’s bad for the planet,” said Schulman. “And it’s bad for our wallets.”
The leak where the birthday party took place — at the intersection of Beacon Street and Park Drive, just past Kenmore Square — is thought to be Boston’s oldest.
National Grid classifies the decades-old leak as a Level 3, non-hazardous leak, meaning it’s not considered potentially explosive.
The company said in a statement this week that it last checked the issue last October. The company vowed to inspect the leak again next month. The plan for now is to fix it as part of a plan to replace all leaky underground pipes within 20 years.
“In our consideration of whether to repair this leak ahead of schedule, we will balance an evaluation of the leak’s status with the disruption its repair could cause to traffic patterns,” a spokeswoman said in an e-mail. “Safety is our biggest priority.”
Utility companies told the Globe last month that they are working hard — and fast — to address seeping gases statewide as best they can.
National Grid alone plans to spend $2.4 billion over the next five years to address leaky pipes throughout their vast underground system.
“We continue to believe that the best way to fix leak-prone pipe is to replace all of it in Massachusetts within 20 years. We are committed and on target to doing that,” said Danielle Williamson, a National Grid spokeswoman.
The party Wednesday started with a performance by members of the Boston Climate Action Network, who put on a canastoria presentation — a European theatrical form that includes props and rhyming — for a small crowd.
After singing the Happy Birthday song to the gas leak, attendees wearing party hats cut the cake.
“We just hope that we don’t have to celebrate any more birthdays,” said Joel Wool, a member of Clean Water Action. “Frankly, we don’t want our infrastructure to keep degrading.”
David Abel of the Globe staff contributed to this article. Steve Annear can be reached at firstname.lastname@example.org. Follow him on Twitter @steveannear.