No. 90-5483. Submitted March 11, 1991. Decided February 5, 1992. Anthony Turrini, Anchorage, Alaska, argued, for appellants. Catherine Fisk, Dept. of Justice, Washington, D.C., argued, for appellee. Appeals from the United States District Court for the District of Minnesota. Before WOLLMAN, Circuit Judge, FLOYD R. GIBSON, Senior Circuit Judge, and BEAM, Circuit Judge. BEAM, Circuit Judge. The National Wildlife Federation, the Minnesota Conservation Federation, the Izaak Walton League of America,