When Bonnie Mueller sees Boathouse Row’s iconic lights dark at night these days, she gets a sinking feeling — like her “heart’s dropping out from inside.”

“It’s one of the things you wouldn’t realize it until it’s gone,” Mueller, secretary of the Schuylkill Navy of Philadelphia, said. “It’s such an iconic image that gets shown all over the world. To see them dark, you realize you don’t appreciate how great it is that they’re lit.”

The sporadic darkness of the Boathouse Row lights is coming to an end just in the nick of time as the nation’s eyes to turn to Philadelphia. The lights are expected to be fully replaced by July 24 — the first day of the Democratic National Convention. But teams of workers are installing the lights literally round-the-clock at this point to make sure it gets done in time, thanks to a large cash infusion from an anonymous donor.

The iconic lights that line the boathouses along Boathouse Row overlooking the Schuylkill River in Fairmount Park were first installed in 1979, and for decades, folks from the Philadelphia Department of Parks and Recreation had to change the lightbulbs twice a year in a painstaking process, said Barry Bessler, the Department’s chief of staff.

So those lights were replaced in 2005 when LED lights were hitting the market in a big way. They promised brighter lights that lasted longer and used far less wattage. They could be hooked up to Phillips Color Kinetics, a computer system installed in one of the boathouses that would control the lighting fixtures, change their colors and perform light shows. At the time, officials projected the new lights would last 20 years.

A decade later though, the lights started to fade. One would go out, and, like Christmas lights, several others around it would go out. The lights weren’t responding to the color commands like they once had, and Bessler said “wear and tear” took hold. Mueller, Bessler and others familiar with what the lights were supposed to look like knew they needed to be replaced.

Within the last three years, Parks and Recreation has attempted to fix the lights in a “patchwork” way, including a large project to fix some of the lights before the Papal visit last September. Problem is, the lighting that’s manufactured now is different than what it was in 2005, so the patchwork fixes still don’t look uniform to the rest of the lighting.

“It still was not adequate in terms of how we wanted it to look, how it should look,” Bessler said. “This is one of the most iconic views in Philadelphia. So we wanted to make sure it would look right when we’re having another party now in 2016.”

Lucky for Parks and Recreation, an anonymous donor approached the Fairmount Park Conservancy earlier this year about helping to fund the light replacement project. In addition to that, the Conservancy had some end-of-the-year cash left over that it helped put toward the project. The total cost hasn’t been released, but those close to the project say it’s in the mid-six-figure range.

But by the time that donor came through and the money was transferred, it was already April. Supplies needed to be ordered from manufacturers overseas and designs had to be put in place for the new lighting fixtures. Teams of workers from an electrical contracting firm are assigned to each boathouse and are now working late into the nights and over the weekend to get the lights turned on by July 24.

Bessler said he’s confident that though the hard deadline is approaching, the lights will be finished just in time.

“It’s a real adrenaline rush trying to get this deadline met,” he said. “But the big project in 2005, changing it over, was really special. And now the system just needs a little TLC.”

Anna Orso was a reporter/curator at Billy Penn from 2014 to 2017.