Greendale is located on the west side of Chilliwack, bordering the east side of the City of Abbotsford. The Vedder River forms the border between Greendale and Yarrow which lies to the South. Greendale, originally called Sumas until 1951 but was renamed because of the name of the adjoining municipality, the District of Sumas (now part of the City of Abbotsford), and also including Sumas, Washington. The area was once a lake at the base of Sumas Mountain. Sumas Lake was drained in the early 1920s. Greendale has experienced two major floods, after the completed drainage, in 1894 and 1948.
The Great Blue Heron Nature Reserve is located in Greendale.