Animal services officers picked up the gator from the 2800 block of Donald Drive around 4 p.m. and brought it back to the facility, Vidal said.
The alligator has been set up in "an appropriate container" and veterinarians have evaluated what to feed it.
"These things are typically pets, and they get too big and people cut them loose or they escape," Vidal said.
Vidal said he does not know what kind of alligator officers recovered, since animal services handles domestic animals.
Sometimes such animals are shipped back to an area of the origin, sometimes euthanized and sometimes given to a facility such as Six Flags Discovery Kingdom in Vallejo, according to Vidal.
A snapping turtle recovered by animal services was taken in by Six Flags in Vallejo last year, he said.
Animal services officials have been in contact with the California Department of Fish and Game, which will determine where the alligator belongs.