<P> Flooding occurs in the watershed due to snowmelt, rainfall, and intense thunderstorms . In higher elevations, snowmelt can cause flood conditions due to rapid snowmelt in spring and early summer . In lower elevations, regional rainstorms and intense thunderstorms can cause flooding in summer and fall . Severe droughts have occurred in the Yellowstone Watershed lasting several years . Droughts have occurred in the basin in 1929 - 42, 1948--62 and 1976 - 82 . The 1977 drought affected most the western United States and lead to decreased streamflows in the watershed . The reduced flow increased dissolved solids concentrations in the basin . Water quality varies across the various rivers in the basin . In mountainous areas, suspended sediment and dissolved solid concentrations are lower than in basin and plain areas . Human activities, including agriculture and mining, along with natural sources contribute to suspended sedimentation levels in plain areas . In addition, fecal bacteria, salt, and selenium contamination is present in some streams within the watershed . </P> <P> An ExxonMobil pipeline which runs from Silver Tip, to Billings, Montana, ruptured about 10 miles (16 km) west of Billings on Friday, July 1, 2011, at about 10: 40 p.m. The resulting spill leaked an estimated 1,500 barrels of oil, equivalent to 63,000 US gallons (240,000 l; 52,000 imp gal), into the Yellowstone River for 56 minutes before it was shut down . As a precaution against a possible explosion, officials in Laurel, Montana evacuated about 140 people on Saturday just after midnight, then allowed them to return at 4 a.m. Montana Governor Brian Schweitzer stated that "The parties responsible will restore the Yellowstone River". </P> <P> According to the Bridger Pipeline LLC, another oil spill occurred near Glendive on January 17, 2015, at 10 a.m. In response, the pipeline company shut down the pipeline at 11 a.m. in effort to prevent further environmental hazards . The company stated that 300--1,200 oil barrels (equivalent to 12,600 to 50,400 US gallons) were spilled into the river . State officials estimated, on the other hand, up to 50,000 US gallons (190,000 l; 42,000 imp gal) of spilled oil . Benzene, a carcinogen, was found in ten to fifteen parts per billion . An EPA official said that "anything above five parts per billion is considered a long - term risk ." Nearly 6,000 people were told not to use municipal water in Glendive due to the elevated levels of cancer - causing benzene found in the Yellowstone River, and in the tap water supplied . Bottled water was provided to their residents . On January 23, 2015, the city water treatment plant was declared decontaminated . City officials declared tap water safe to consume . </P> <P> The Wyoming company from True Companies' Poplar pipeline system involved in this incident has a history of nine oil spills in 2006--14 leaking an amount of 11,000 gallons of crude . Also, their sister company Belle Fourche Pipeline owned by Tad True and their family, recorded twenty - one incidents in the same period leaking 272,832 gallons of oil, both companies had federal fines levied against them and appear in governments records . The oil cleanup on Yellowstone River was put on hold for one month or more on February 3, 2015 until the ice melts . Montana Department of Environmental Quality was monitoring an area spanning a ninety - mile stretch of the Yellowstone, from the spill site downstream to a bridge just across the North Dakota border . </P>

Where is the yellowstone river located on a map