The porpoise was seen swimming near the surface of the canal of mixed tidal and fresh water, and at times forcing air out of its blowhole.
Biologists with the Santa Clara Valley Water District speculate that the animal might have ended up in the creek during high tide Wednesday night. The water in the creek was deep enough for the porpoise to swim in, but it was too shallow for it to swim back out the way it came.
According to the American Cetacean Society, harbor porpoises are generally small but get stocky through their mid-section before tapering to a slender tail. On the tops of their bodies, harbor porpoises are often dark gray or brown, and their bellies are usually white.
They grow to a maximum length of 6-feet and feed mostly on fish.