Nussbaum et al. Nests have been observed in many soil types from sandy to very hard. Nests must have a relatively high internal humidity for eggs to develop and hatch properly. Individuals normally associate with permanent ponds, lakes, streams, irrigation ditches or permanent pools along intermittant streams. Hatchlings may be subject to rapid death by desiccation if exposed to hot, dry conditions.
Most activity is diurnal but some crepuscular and nocturnal activity has been observed.
Individuals are active all year where climates are warm but hibernate during cold periods elsewhere. Other long distance movements may be in response to drying of local bodies of water or other factors. Sexual maturity is thought to be attained in about eight years. This is the only abundant native turtle in California. Hatchlings and juveniles are preyed upon by a variety of vertebrate predators including certain fishes, bullfrogs, garter snakes, wading birds, and some mammals.