Thurston County is located on the southern end of Puget Sound in Washington State. It is bordered on the west by Grays Harbor, the northwest by Mason County, the northeast and east by Pierce County and the south by Lewis County. As of the 2010 U.S. Census, Thurston County had a total land area of 721.96 square miles and a population of 252,264. Olympia is the largest city with a population of 46,478. Also of interest:
- Intersecting watershed sub-basins(5): Upper Chehalis, Lower Chehalis, Nisqually, Deschutes and Puget Sound.
- Major lakes: Summit Lake, Black Lake, Capitol Lake, Long Lake, Lake Saint Clair and Lake Lawrence.
- Major rivers: Nisqually River, Deschutes River, Black River, Chehalis River and Skookumchuck River.
- Quiemuth Peak (2,922 feet) is the hightest point in Thurston County.