The District owns and operates Rancho Cañada del Oro Open Space Preserve, Sierra Vista Open Space Preserve, Coyote Valley Open Space Preserve and Máyyan 'Ooyákma-Coyote Ridge Open Space Preserve. The District also manages and maintains properties that are currently closed to the public, including Diablo Foothills, Palassou Ridge, Coyote Valley Conservation Area, El Toro, and Santa Cruz Mountains properties. The District provides a variety of activities that are free to the public, such as guided nature hikes, bike and equestrian rides, photography walks, educational programs for children, and stargazing sessions. The District engages in resource management, such as protecting waterways and natural resources and removing invasive plants, preserving cultural artifacts and supporting agriculture and ranching. The District has two active grant programs that provide funds for urban subjects, the Urban Grant Program and the 20% Funding Program.

The District owns and manages over 70,000 acres of land in 27 open space preserves, 25 of which are open to the public free of charge, featuring more than 250 miles of trails. The open space preserves are open, 365 days a year, from a half-hour before sunrise until a half-hour after sunset. Open space preserves are generally kept in a natural condition in order to best protect the environment and wildlife habitat and are developed with only the amenities needed to provide low-intensity recreation. In addition to preserve maintenance, the District is involved in resource management, which includes management of both natural and cultural resources. Natural resource management generally consists of protecting, restoring, enhancing, and monitoring native vegetation and wildlife, and monitoring and protecting the quality of geological and hydrological conditions. Cultural resource management consists of identifying and evaluating and protecting archeological sites, key historical structures, and cultural landscapes.