In the Santa Monica Mountains, Western Pond Turtles can be found in ponds, streams, creeks, marshes, and irrigation ditches, with abundant vegetation, and either rocky or muddy bottoms, in woodland, forest, and grassland. In streams, turtles prefer pools to shallower areas. Logs, rocks, cattail mats, and exposed banks are required for basking.
Adult turtles eat aquatic plants, invertebrates, worms, frog and salamander eggs and larvae, crayfish, carrion, and occasionally frogs and fish.
In the Santa Monica Mountains and Simi Hills, mating occurs in April and May. Females lay a clutch of 2 - 11 eggs in a nest usually located along stream or pond margins. Some females may lay two clutches in a year while others lay eggs every other year.
Western Pond Turtle populations have suffered population declines in most of its range due to habitat loss and alteration caused by human activity. Western Pond Turtles are currently listed as a California Species of Special Concern (California Department of Fish and Wildlife) and are a park species of special concern.