Medical Lake is a city in Spokane County, Washington, United States. The population was 5,060 at the 2010 census. It is home to a psychiatric hospital, Eastern State Hospital. Medical Lake was officially incorporated on June 21, 1880. It took its name from a nearby lake Native Americans believed held medicinal qualities.The city is named for an eponymous lake, and lies on that lake's east side. There are many lakes within a few miles of the city, including Medical and West Medical Lakes, Silver Lake, Clear Lake, and numerous smaller lakes south of the city. Driving distance from downtown Spokane is 16 miles along Interstate 90 and Washington State Route 902, the latter of which runs through the city. Eastern State Hospital is across the lake from town in between West Medical Lake and Medical Lake. Fairchild Air Force Base is located just north of town. Geologically, the city lies on basalt flows that were heavily eroded by catastrophic flooding at the end of the Ice Age, so the city and environs is in the Channeled Scablands.