File:Lake Oahe, Dakotas (ASTER).jpg

English: The Missouri River, the nation's longest, is struggling in the grips of a severe 6-year drought. In North Dakota, 374 km long Lake Oahe, the nation's fourth largest reservoir, is so low that it has left the state. From Bismarck to the South Dakota border, more than 100 km have reverted to a narrow river where the lake was once 8 km wide. Left behind are weedy mudflats and boat ramps stranded 2 km from water. The drought's list of effects is long and painful: shortage of drinking and irrigation water; reduction in hydroelectric capacity; decrease in tourism; reduction in shipping; threats to endangered wildlife. The cause is the continuing yearly shortage of snowpack in the Rocky Mountains in Montana, where the Missouri River has its headwaters. The left image was acquired by Landsat on May 18, 2000, and the right one on April 4, 2004 by ASTER. Both cover an area of 28.7 x 65.6 km, and are centered along the North and South Dakota border at 46 degrees north latitude, 100.5 degrees west longitude.