Sammamish River

About

The Sammamish River runs for about 13.7 miles (22.0 km) through portions of King County, Washington, draining Lake Sammamish into Lake Washington. It flows out of Lake Sammamish at Marymoor Park in Redmond, before continuing through suburban residential areas in Redmond, Woodinville, Bothell, and Kenmore. About 32% of the river's riparian habitat is forested, with the invasive reed canarygrass found across its course. The river hosts fish such as salmon as they migrate between the lakes. It has four major tributary streams: Bear Creek, North Creek, Swamp Creek, and Little Bear Creek. The floodplain was carved out by a glacial meltwater channel during the Vashon Glaciation, about 15,000 years ago, resulting in a geology dominated by glacial deposits and alluvium.

The Marymoor Archaeological Site is located near the river's mouth, estimated to be around 2400 to 8000 years old. At the time of contact, the area was inhabited by the Sammamish people, a division of the broader Duwamish, a Coast Salish nation. European settlement of the valley began during the 1870s, and loggers cleared its forests over the following decades. The river was subject to heavy modifications and flood control measures. The opening of the Lake Washington Ship Canal in 1917 caused the level of Lake Washington to drop, and a local drainage district attempted to alleviate floods by constructing drainage ditches and straightening its upper course. The U.S Army Corps of Engineers oversaw measures to channelize and dredge the river during the 1960s, expanding a weir near the river's source. Redmond entered a period of extensive growth and urbanization in the late 20th century, while riparian habitat restoration efforts were taken across the river's course during the 2010s.