Moses Coulee Coulee, a National Natural Landmark, one of the largest examples of bars created by the Channeled Scablands outburst floods. Moses Coulee cuts into the Waterville Plateau, which lies in the northwest corner of the Columbia River Plateau. The plateau is part of the Columbia River Basalt Group, a large igneous province that lies across parts of the states of Washington, Oregon, and Idaho in the United States of America. During late Miocene and early Pliocene times, one of the largest flood basalts ever to appear on the earth's surface engulfed about 163,700 km² (63,000 mile²) of the Pacific Northwest, forming
Grand Coulee, Washington 100 females age 18 and over, there were 80.5 males. The median income for a household in the city was $21,818, and the median income for a family was $29,375. Males had a median income of $25,625 versus $18,125 for females. The per capita income for the city was $13,639. About 11.7% of families and 19.3% of the population were below the poverty line, including 25.3% of those under age 18 and 17.6% of those age 65 or over. Grand Coulee, Washington Grand Coulee is a city in Grant County, Washington, United States. The population was 988 at the 2010