 Between 2004 and 2013 an average of 74 @,@ 325 acres ( 300 @.@ 78 km2 ) were burned by fires per year with a maximum of 346 @,@ 500 acres ( 1 @,@ 402 km2 ) in 2007 and a minimum of 152 acres ( 0 @.@ 62 km2 ) in 2008 . For example , in 2012 there were 26 fires started by people and 109 started by lightning , which together burned a total of 152 @,@ 000 acres ( 620 km2 ) . The Trinity Ridge Fire alone burned 146 @,@ 800 acres ( <unk> km2 ) over two months , although it was not confined to Boise National Forest lands . 
