Other proposed dams further upstream were not built either : the High Mountain Sheep Dam above the confluence with the Salmon River , and the Nez Perce Dam , just below it . Following the September 11 attacks in 2001 , the road across the Lower Granite Dam was closed for over six years ; it reopened for weekend traffic in May 2008 . The sand dune area downstream on the south shore ( ) , accessed over the dam , was popular with local college students from Washington State University and the University of Idaho
September 11 attacks
September 11 attacks
Lower Granite Dam