A combination of record snowmelt and heavy rain raised water levels along the Missouri River and its tributaries in the northern Rocky Mountains and Plains in early June 2011. Flooding affected parts of Montana, North Dakota, and South Dakota, USA Today reported, and was forecast to continue through at least late June.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured the top image on June 1, 2011. The bottom image, from June 4, 2010, shows the area almost a year earlier. These images show parts of the Missouri and Souris Rivers in North Dakota. Both images use a combination of visible and infrared light to increase contrast between water and land. Water is navy. Vegetation is green. Bare ground is brown. Clouds are pale blue-green.
Near Williston, the normally thin Missouri River meanders through a vegetation-lined valley before reaching the reservoir of Lake Sakakawea. On June 1, 2011, however, water nearly fills the river valley. On June 2, 2011, the Advanced Hydrological Prediction Service (AHPS) of the U.S. National Weather Service reported that the Missouri River was at major flood stage near Williston, and was close to its record level of 28.0 feet (8.5 meters) set in 1912. At 7:30 a.m. local time on June 2, the Missouri reached 27.85 feet (8.49 meters) near Williston. The AHPS projected that the river would reach 28 feet over the next few days.
The image from June 1, 2011, also shows unusually high water levels along the Souris River, which crosses the U.S.-Canada border. In 2010, this river thins enough to disappear from the satellite sensor’s view in some places. Despite some thin clouds in June 2011, the Souris River is clearly higher, especially south of Bantry.
As of June 2, 2011, the AHPS reported, the Souris River was at major flood stage near both Foxholm and Bantry. At 5:00 a.m. local time the Souris River reached 14.46 feet (4.41 meters) near Bantry, slightly below the record level of 14.59 feet (4.45 meters) set in 1976. At 7:15 a.m. local time, the Souris River reached 16.27 feet (4.96 meters) near Foxholm, a little below the record level of 17.17 feet (5.23 meters) set in 1976. The AHPS projected that the Souris would rise somewhat at both locations.
As MODIS captured flooding in North Dakota, communities in South Dakota braced for anticipated floods. The Dickinson Press reported that the governor of South Dakota urged residents to evacuate Pierre, Fort Pierre, and Dakota Dunes. Meanwhile, the governor of Montana asked the president to declare a major disaster for that flood-struck state. On May 31, 2011, the U.S. Army Corps of Engineers established a joint information center related to flooding along the Missouri River.