Washington State Route 17 Coulee City–Brewster branch of PSH 10 was codified in 1931 as a branch of State Road 10 and re-codified in 1937, during the creation of the primary and secondary state highways; however, the highway was not built between Sims Corner and Bridgeport until the 1950s. The Soap Lake–Coulee City branch of PSH 7 was established in 1937 to serve as an alternate route to SSH 2F, avoiding the Grand Coulee Dam. In 1951, the PSH 10 branch between Bridgeport and Brewster was moved north of the Columbia River via the newly built Columbia River Bridge on the present route of
Etzikom Coulee of at its origin east of Stirling Lake (to which it is connected by the Sluice Gate Channel) to an elevation of at its mouth at Pakowki Lake, over a length of more than . The coulee builds a canyon up to deep. Etzikom Coulee Etzikom Coulee is a coulee located in Southern Alberta, Canada. The waterway was formed as a glacial spillway channel at the end of the last ice age. The Etzikom Coulee begins northeast of the town of Stirling, and makes its way southeast of the Hamlet of Wrentham, after that it passes by the Hamlet of