Within California, disaster planning and operations are based on the concepts of local operational control during disasters and mutual aid to provide the additional resources necessary to augment disaster response organizations in the disaster area. The entity designated to coordinate disaster response resources within the geographical boundaries of a county is the Operational Area (OA), which consists of all political entities of a County. The OA is responsible for coordinating local response programs, for utilizing all available local resources, for instituting mutual aid requests with other Counties within the local mutual aid region and for instituting and validating State resource requests.

Within the OA, an Operational Area Disaster Medical Coordinator (OADMHC) is responsible for medical and health response. Normally this position is appointed by the County Public Health Officer or Board of Supervisors and will staff the medical and health branch in the OA EOC. Unlike fire and law, however, there is no designated governmental structure in each County responsible for medical disaster planning and operations. In many cases, these requirements are tasked to the agency responsible for emergency medical services for the County under the direction of the Public Health Officer. OES organizes the OAs into six mutual aid regions to provide mutual aid support and a regional emergency response system. At the regional level, EMSA and DHS jointly appoint a Regional Disaster Medical and Health Coordinator (RDMHC) whose responsibilities include supporting the mutual aid requests of the OADMHC for disaster response within the region and providing mutual aid support to other areas of the state in support of the state medical response system. The RDMHC also serves as an information source to the state medical and health response system.

Medical and health response planning at the state level is accomplished by several departments within the California Health and Human Services Agency and coordinated with plans prepared by the Governor's Office of Emergency Services. The medical response relies on mutual aid from the unaffected mutual aid regions within the State and state resources including medical personnel and equipment from DHS, state organized Disaster Medical Assistance Teams (DMAT), and the California National Guard. Additionally, the state contracts with medical suppliers and other private and public medical providers to supply medical resources as needed.

EMSA is responsible to coordinate the procurement of medical resources, and in conjunction with DHS runs the JEOC, a combined EOC whose purpose is to set state medical and health policy and procedures, procure medical personnel through the Regional Medical Mutual Aid system and supplies and equipment through agreements with large medical supply vendors throughout the State. Additionally, state medical and health personnel run the Medical and Health Branch in each activated OES REOC. The Branch has the responsibility to coordinate the medical and health response with other emergency response functions, coordinate with other state agencies such as the California National Guard for support to the medical and health response, and insure that the medical and health response supports the overall state response priorities as established by OES.