Welcome back: Dolphins spotted in the Bronx River, a sign of cleaner waters

Dolphins have been spotted swimming in the Bronx River, a sign that the once-infamous waterway has become a healthy home for marine life, according to the Parks Department.

“This is great news” The department tweeted on Thursday. “This shows that years of efforts to restore the river as a healthy habitat are working.”

The department has attached video of the dolphins playing in the water outside Starlight Park, where residents of the area gave the creatures a proper welcome in the Bronx.

“Hey fucking crazy bro,” Nick Banquo said as the dolphins surfaced.

“Someone please tell me why [the f-ck] Are there dolphins in the damn park?” he captioned the video. “Damn shocked me.”

But Mark Sanchez, deputy director of the New York City City Parks Department, said there was no mystery.

“Animals will basically be wherever there is food for them,” he told The Post on Friday.

Sanchez said the Parks Department fills the river with fish every year as part of its restoration efforts, including species such as Alewife, which dolphins love to eat.

“This is part of a long-standing restoration effort — a multi-year project, at least while I’m with the Parks Department,” said Sanchez, who joined the agency in 2005.

“This certainly indicates an improvement in the condition of the water, that the water is able to support the fish,” he said.

Sanchez said aquatic mammals have become more common in urban waterways in recent years, including seals, porpoises and other dolphins.

On Wednesday, Sanchez said, dolphins were also seen in another historically polluted waterway, Newtown Creek, between Brooklyn and Queens.

Sanchez said the Parks Department has organized seal-watching expeditions that curious New Yorkers can join.

But as aquatic mammals are becoming more common, he asked people to leave space for these creatures, rather than crowd and photograph them.

“We are very pleased that the animals were able to show themselves and make their presence known,” he said.

“This is a great thing,” he added. “We should expect them to continue to see them.”