"Ahoy, you can't park there! At least the captain was kind enough to anchor his boat to the street sign before he abandoned ship," the department tweeted.
The boat was removed by city crews and taken to the local tow yard.
Irwindale Police Sgt. Rudy Gatto said the boat's registration was out of date and a notice will be sent to the owner. Gatto said the boat had not been reported stolen.