The Environmental Stewardship Unit was established in 2001 as part of the Pro Parks Levy's “Environmental Stewardship, Maintenance, and Programming” category. As part of the Levy, this program sought to enhance park maintenance, environmental awareness, and provide park programs for youth and seniors by establishing the Environmental Stewardship program. Through the Environmental Stewardship Unit (ESU), park staff increased conservation efforts and established environmental education programming and summer day camps. ESU also initiated efforts to increase recycling and use of green products.

The Department of Parks and Recreation maintains the City's parks, shorelines, and boulevards; and administers community centers, public golf courses, and other athletic and cultural facilities. Seattle's first park was established in 1884 after David Denny donated land to the City for that purpose. At that time, a three-member park committee, with limited authority, was created to manage the nascent park system. A Board of Parks Commissioners was established in 1890 with control over all public parks and authority to appoint a Parks Superintendent. In 1896, the City Charter created the position of Superintendent of Streets, Sewers and Parks. The Parks Department became a separate entity in 1904. In 1926, a City Charter amendment abolished the position of Superintendent, distributing its responsibilities between the Head Gardener and the Landscape Architect. A 1948 City Charter amendment required the Board of Park Commissioners to appoint a park superintendent to administer the department. In 1967, another City Charter Amendment reconstituted the Board as an advisory body to the Mayor and City Council, changed the agency name to Department of Parks and Recreation, and placed fiscal and operational administration under the superintendent. In 1902 the City hired the Olmsted Brothers, the country's premier landscape architectural firm, to design a parks and boulevards system. Although not all of the plan was implemented, the Olmsted legacy is evident in many of Seattle's parks and boulevards. The City acquired significant amounts of property for park purposes following the turn of the 20th Century, but in 1926 further acquisition was limited by a City Charter amendment that stipulated only money in the Park Fund could be used for that purpose. However, in the 1970s the Forward Thrust Bond issue, along with federal grants and the Seattle Model City Program, supported the largest expansion of the Park system in Seattle history. These programs funded more than 70 new parks and park facilities. The Department manages over 6,000 acres of park land, over two dozen community centers, five municipal golf courses, the Aquarium, and many other recreational and athletic facilities.