 The Idaho Batholith <unk> most of Boise National Forest , forming the forest 's Boise , Salmon River , and West mountain ranges ; the forest reaches a maximum elevation of 9 @,@ 730 feet ( 2 @,@ 970 m ) on Steel Mountain . Common land cover includes sagebrush steppe and spruce @-@ fir forests ; there are 9 @,@ 600 miles ( 15 @,@ 400 km ) of streams and rivers and 15 @,@ 400 acres ( 62 km2 ) of lakes and reservoirs . Boise National Forest contains 75 percent of the known populations of <unk> 's <unk> , a flowering plant endemic to Idaho . 
