In 1991 , the Bureau of Land Management approved a new grazing allotment management plan . It was based on the agreements made by the Trout Creek Mountain Working Group , and it took effect in 1992 . Since then , vegetation in riparian areas of the Trout Creek Mountains has recovered , and studies by the United States Fish and Wildlife Service have found that the Lahontan cutthroat trout population , still listed as threatened , is also recovering .