One of the largest reservoirs in the US, Lake Texoma lies on the border of Oklahoma and Texas and is formed by the buildup of water at Denison Dam on the Red River. When the water levels get too high, as they have in recent weeks, the Army Corps opens sluices, called floodgates, at the bottom of the lake to drain the water into the river. The flowing water creates cyclonic action, much like a tornado, which is widest at the top and tapers down at its tip, said Parkey.If the whirlpool were large enough, it would be easy for a boat to be caught up in it, Parkey said. To avert a watery disaster, the Army Corps has marked the area with buoys and signs to keep people away. He said the entire area is off-limits for boats.Video Credit ; usacetulsa