Because of fluctuating demands on the electrical grid, the dam release into the Colorado River rises and falls dramatically on a daily basis. After the dam was completed in 1964, there were few restrictions on hydro-power generation. The minimum dam release was set at a meager (increased to during the summer whitewater rafting season), with a maximum of during peak times; to respond to changing power demands, river flows could double or even triple in the space of an hour. This caused severe erosion of the Colorado River banks downstream, damaging habitat for native fish and causing danger for boaters, who could get stuck whenever the river flow dropped too quickly. In 1990 temporary restrictions were put in place on dam operations, before the release of a final environmental impact statement (EIS).