Amateur Radio Emergency Services (ARES) is a program of the American Radio Relay League (ARRL), and is comprised of licensed amateur radio operators who are interested in utilizing their skills and equipment for public service and in times of disaster. Every licensed amateur radio operator, regardless of membership in the ARRL is eligible to apply for membership in ARES.
When not actively engaged in disaster response, Sacramento County ARES members prepare for such times by participating in readiness drills, trainings, and practices, and by providing radio communication services at various community events such as fun runs, marathons and horse races.
Within the Incident Command System, ARES is defined and functions as a "Group", and can be called upon for its services by various served organizations.
The primary and priority organization served by Sacramento County ARES is the Sacramento County Office of Emergency Services (County OES). Thus, in a large scale disaster if the Red Cross needed Amateur Radio Operators as is often the case in their shelter operations, their request would be coordinated through the County OES. There are several reasons for coordinating services through the county, some of which are that it allows the county to direct resources to where they are needed most, it allows for worker compensation under the Disaster Services Worker provision, and it counts members time towards meeting the required local contribution amount (FEMA pays 75% / Local pays 25%).
ARES leadership is composed of Emergency Coordinators (EC) at the Section, District, and County levels, and they are appointed by the elected ARRL Section Manager. The complete Sacramento County ARES Organization Chart is available here.
As you might have already discovered, there are two "Sacramento ARES" websites, there this one that you are looking at now which is for the COUNTY LEVEL, and then there is the Sacramento Valley Regional one which is for the SECTION LEVEL. The Section level of ARES includes 20 California counties: Alpine, Amador, Butte, Colusa, El Dorado, Glenn, Lassen, Modoc, Nevada, Placer, Plumas, Sacramento, Shasta, Sierra, Siskiyou, Sutter, Tehama, Trinity, Yolo, and Yuba. You will find a good diagram depicting this here.
More information about Sacramento County ARES may be found here.