The Office of Site Operations (OSO) is responsible for implementing long-term surveillance and maintenance (LTS&M) at 101 sites that have been transferred to the Office of Legacy Management (LM) to ensure sustainable protection of human health and the environment. LM is also preparing for the transition of four other sites over the next three years at which LM will also conduct LTS&M. Important activities that OSO performs at transition sites prior to them formally becoming the responsibility of LM include developing LTS&M plans for them and identifying other regulatory requirements that LM will have for the sites including cultural and historic, and natural heritage resources. The director of OSO also has responsibility for LM’s Safety and Health, Quality Assurance, and Environmental Management Systems programs, as well as the Office’s international activities. In addition, the OSO director leads LM’s interagency work on Defense-Related Uranium Mines and manages the Uranium Leasing Program in western Colorado.