Austin residents are accustomed to seeing changes in the city’s skyline, but the city’s tallest tower is drawing attention for an off-color reason.

Large, rust-colored stains running down the white and glass exterior of Waterline, the 74-story mixed-use tower under construction in the Rainey Street District, are drawing speculation from passersby and social media users about what’s happening to the city’s new marquee structure.

“It’s a brand new building, the tallest in Texas, and not even open yet and this is already happening,” a user on the Reddit social media site said in a post about the stains. 

It’s nothing to worry about, according to an executive with Lincoln Property Co., which is developing the building with San Antonio-based Kairoi Residential. The discoloration is overflow from the building’s standpipe system and expected to be cleaned soon.

“It’s normal. It’s basically just a bunch of dirt and grime,” said Seth Johnston, executive vice president for Lincoln’s Austin and San Antonio operations.

A standpipe, or riser, is part of the rigid, vertical piping built into multi-story buildings as connection points for fire hoses.

Johnston said the Austin Fire Department is conducting flow tests of the pipes and the discoloration is the result of grime that built up during  of construction, which began in 2022.

“It should be cleaned up pretty quick,” he said.

The $520 million tower is under construction near Lady Bird Lake and Waller Creek. At more than 1,000 feet, it is the tallest building in Texas.

Plans for the whopping project include office space, more than 350 apartments, retail and restaurant space, a 250-room hotel, indoor and outdoor amenity spaces and direct access to the Ann and Roy Butler Hike-and-Bike Trail.

The building is expected to be complete this summer, though final build-out of the interior may take longer to complete.