Harbor porpoise spotted swimming in Napa River

NAPA, Calif. (KGO) -- A rare sight is attracting spectators in wine country -- a harbor porpoise has been spotted swimming in the Napa River!

As late as 9 p.m. on Thursday, tourists in Downtown Napa watched it pop out of the Napa River near the Third Street Bridge.

"And it will pop up two times then go back under, and then shortly thereafter pop up two more times and then be gone maybe 10 minutes and do the same thing over and over again," Napa resident Kathleen Haughen.

"And he's not gray. He's like a brown, purple color. But he's a little guy," Napa resident Ronda Gupton-Pruett said.

That description has marine biologists for Golden Gate Cetacean Research convinced this is a harbor porpoise. It may have followed a food source up river.

"I noticed the dorsal fin. It's like wait that's not a sea lion," Napa resident David Meyers said.

Meyers says he spotted the porpoise as early as last Friday. It was just off his boat dock about 10 miles south of Downtown Napa.

"I know the water is real salty now, with no rain and stuff. So I'm not surprised something would come up here that usually isn't here," Meyers said.

The Marine Mammal Center in Sausalito says it's aware the harbor porpoise is there. Biologists say there is salt water in the river and it does not seem distressed, so they're not worried. They think it will likely swim back to the bay.

Marine biologists say it's rare, but another harbor porpoise was seen in the Napa River last summer.

They advise boaters and swimmers to not approach the porpoise because it is a wild animal.