Grand Coulee Dam the Columbia River formed the Grand Coulee, but it was revealed in the mid-late 20th century that massive floods from Lake Missoula carved most of the gorge. The earliest known proposal to irrigate the Grand Coulee with the Columbia River dates to 1892, when the "Coulee City News" and "The Spokesman Review" reported on a scheme by a man named Laughlin McLean to construct a dam across the Columbia River, high enough that water would back up into the Grand Coulee. A dam that size would have its reservoir encroach into Canada, which would violate treaties. Soon after the Bureau
Foster Coulee Foster Coulee Foster Coulee is a coulee in Douglas County, Washington. Like the larger Moses Coulee nearby, it was formed during the Missoula Floods at the end of the last ice age, some 14,000 years ago. Washington State Route 17 between Bridgeport, Washington and Coulee City, Washington follows East Foster Creek along much of the coulee's valley floor. East Foster Creek now flows east to west through Foster Coulee to Grand Coulee. The United States Geological Survey quadrangle map "Foster Coulee" is named for this prominent feature. Foster Coulee was formed during the Missoula Floods. The Okanogan lobe of the