By the 1970s and 1980s , a century of intense cattle grazing had reduced much of the riparian vegetation along stream banks in the Trout Creek Mountains and elsewhere in the Great Basin . As a result , stream banks were eroding and upland vegetation was encroaching into riparian zones . Aspen populations declined as grazing cattle eliminated young trees , decreasing shade over streams and raising water temperatures . These conditions put the rare Lahontan cutthroat trout population at risk . Since the Lahontan was officially designated as a threatened species , environmental groups began advocating the cancellation of grazing permits in the Trout Creek Mountains .