(a) In order to further the purposes of the Wilderness Act [16 U.S.C. 1131 et seq.], there is hereby designated, subject to valid existing rights, the Pasayten Wilderness within and as a part of the Okanogan National Forest and the Mount Baker National Forest, comprising an area of about five hundred thousand acres lying east of Ross Lake, as generally depicted in the area designated as Pasayten Wilderness on the map referred to in section 90 of this title.

(b) The previous classification of the North Cascades Primitive Area is hereby abolished.