As used in this subchapter—

(1) the term "excluded area" means one of the four areas specifically excluded from the recreation area, as generally depicted on the map referred to in section 460bbb–2(b) of this title;

(2) the term "forest plan" means the land and resource management plan for the Six Rivers National Forest prepared pursuant to section 1604 of this title;

(3) the term "recreation area" means the Smith River National Recreation Area established by section 460bbb–2 of this title;

(4) the term "Secretary" means the Secretary of Agriculture; and

(5) the term "inner gorge" means the inherently unstable steep slope (65 percent gradient or more) immediately adjacent to the stream or river channel, extending from the channel or recent floodplain to the first significant break in slope (usually 15 percent or more).