The Merced County Sheriff's Office shared a photo of the pup being pulled from the water.
Deputies say witnesses saw the dog struggling to get out and tried to save it, but couldn't reach the animal because of the slick plastic banks.
When deputies arrived, they encountered the same problem.
But Deputy Diane Rentfrow overheard the radio traffic, grabbed a fishing net from her home and brought it to the scene.
Another deputy was able to use it to fish the pup out of the water to safety.