Dolphins typically are not seen within city limits, especially in the river next to Starlight Park.
But a video reposted on Twitter by the city's Parks Department shows the two dolphins swimming along the river.
"This is great news—it shows that the decades-long effort to restore the river as a healthy habitat is working. We believe these dolphins naturally found their way to the river in search of fish," the Parks Department said in a tweet.
"That is very indicative of the water quality improving in the Bronx River," said Adriana Caminero of the Parks Department.
According to Caminero, efforts made since the 1970s, when congress passed the clean water act, are working.
"I'm an urban park ranger here in the Bronx, and we see seals, which si another sign of the improved water quality here," Caminero said.
Howard Rosenbaum of the Wildlife Conservation Society, said that it appears that the city's most recent dolphin visitors made their way into the river system from the ocean, and based on the video, appear happy!
"I don't see any signs of distress for these animals right now. But we want to keep an eye on that," Rosenbaum said.
Officials with the Parks Department are advising residents that if you do happen to glimpse the dolphins on your next walk, give them space and do not disturb them.