Some BART riders have called a recent Twitter ad blitz around Powell Station “irritating” and “overkill,” but city officials are calling it illegal.

Or at least part of it.

The social media company launched an ad campaign this week in San Francisco and New York City that covered the walls of the station with images of user tweets about Twitter.

All well and good, if potentially annoying for some viewers, but the campaign continued outside with sidewalk chalk stencils extending into the Tenderloin — and that puts it in breach of The City’s vandalism laws, the Department of Public Works said Thursday.

“Our sidewalks are not to be used for commercial purposes, they are not billboards,” said Rachel Gordon, a spokesperson for DPW. “Any company that advertises on our sidewalks is breaking the law.”

Gordon said DPW will typically send crews out to remove the stencils and contact the person or company responsible to collect the cost of the cleanup.

“Our crews really should be focused on other areas, but we want to keep our sidewalks free of commercial content,” Gordon said.

A Twitter spokesperson on Thursday said the company’s media agency had “confirmed necessary approvals ahead of the chalk installation.”

“We haven’t been made aware of any legal issues related to the chalk. We will of course comply with any requests made by the city,” the spokesperson said.

Twitter is not the first company to run afoul of The City’s strict vandalism laws with sidewalk stencils.

Lyft, to give one recent example, drew legal action from City Attorney Dennis Herrera in 2015 after it stenciled ads on sidewalks across The City.

@Twitter has spray painted tweets all over the sidewalk in the Tenderloin, between tents & people without homes, in what is possibly the most disgusting, obvious display of tech refusal to be accountable for their role in San Francisco’s income inequality crisis to date. pic.twitter.com/aEMeY7Dd2w

— Charlie (@OneCharlieGray) September 11, 2019

The ads all over Powell BART are irritating. This is offensive. @Twitter actively fought the latest ballot measure meant to provide better support for our homeless neighbors, benefits from tax breaks even when it doesn't fulfill their terms, and is exacerbating inequality here. https://t.co/6ya8Zz7jr4

— jennifer (@jennifer_jserra) September 12, 2019

Twitter ads on Powell Street Bart– such an overkill.
As if we need to be reminded of its presence.
Still, better than the Sephora blitz at Civic Center Bart pic.twitter.com/JZ9z0dG705

— Molly (@mollykarlthefog) September 12, 2019