SEATTLE — The National Park Service says it has launched a three-year process to determine whether to reintroduce grizzly bears into the North Cascade Mountains of Washington state. In a news release Thursday, the park service said it would begin developing an environmental-impact statement evaluating a “variety of options for the future of the grizzly bear in the area.” Director Jonathan B. Jarvis stressed that no decision has been made to reintroduce the bears, but the process is required under federal law. The agency said it would work with the U.S. Forest Service, the state and the public in making any decisions. Federal authorities listed the grizzly bear as threatened the lower 48 states in 1975. The park service says grizzlies have been seen in the Cascades north of the Canadian border, but not in Washington state in several years.