Grand Coulee at the higher side of the flexure. Encountering the steep slope of the monocline, the new river would have cascaded off the rim, down onto a broad plain where Coulee City and Dry Falls State Park now stand. Upper Grand Coulee began as an cascade just north of Coulee City. As the rush of water eroded the surface, it steepened into a waterfall. The falls continued to erode backward (northward) creating the canyon. When the falls reached the divide into Lake Columbia, i.e., preglacial Columbia Valley, it disappeared, leaving the elongated notch. Today, the waters of the Lake Roosevelt are
Coulee City, Washington males. The median income for a household in the town was $25,938, and the median income for a family was $42,500. Males had a median income of $31,375 versus $17,250 for females. The per capita income for the town was $14,411. About 14.9% of families and 22.1% of the population were below the poverty line, including 29.2% of those under age 18 and 11.7% of those age 65 or over. Coulee City, Washington Coulee City is a town in Grant County, Washington. The population was 562 at the 2010 census. The town was named after nearby Grand Coulee. Coulee City