▁possibilities ▁of ▁down stream ▁ir rig ation , ▁scient ists ▁determined ▁that ▁it ▁would ▁also ▁destroy ▁valuable ▁wet land ▁e cos ystem s ▁and ▁alter ▁the ▁river ▁hydro log y ▁throughout ▁the ▁area ▁of ▁its ▁extent , ▁in ▁the ▁res er voir ▁and ▁far ▁down stream . ▁▁ ▁Under ▁pressure ▁from ▁environmental ▁activ ist ▁groups , ▁the ▁Army ▁Corps ▁of ▁Engine ers ▁developed ▁a ▁mit ig ation ▁plan ▁that ▁represents ▁a ▁major ▁departure ▁from ▁the ▁previous ▁treat y ▁d ams . ▁This ▁plan ▁addressed ▁concerns ▁about ▁fish ▁by ▁building ▁h atch eries , ▁acquired ▁land ▁to ▁serve ▁as ▁gra zing ▁areas ▁for ▁animals ▁whose ▁normal ▁ranges ▁were ▁sub mer ged , ▁and ▁implemented ▁a ▁techn ological ▁fix ▁as ▁part ▁of ▁the ▁dam ▁project ▁that ▁enabled ▁control ▁of ▁the ▁temperature ▁of ▁water ▁released ▁from ▁the ▁dam . ▁ ▁The ▁local ▁environmental ▁impact ▁of ▁the ▁Lib by ▁Dam ▁was ▁to ▁flo od ▁ 4 0 , 0 0 0 ▁acres ▁( around ▁ 1 6 2 ▁square ▁kilom eters ), ▁alter ing ▁down stream ▁and ▁up stream ▁e cos ystem s . ▁This ▁was ▁the ▁greatest ▁direct ▁environmental ▁effect ▁of ▁the ▁treat y ▁in ▁the ▁United ▁States . ▁While ▁the ▁Lib by ▁Dam ▁and ▁Lake ▁Ko oc an usa ▁were ▁the ▁most ▁visible ▁results ▁of ▁the ▁treat y ▁in ▁the ▁US , ▁there ▁were ▁long - r anging ▁environmental ▁imp lications ▁of ▁the ▁new ▁management ▁regime . ▁The ▁increased ▁storage ▁capacity ▁in ▁the ▁Upper ▁Columbia ▁d ams ▁afford ed ▁river ▁man agers ▁a ▁much ▁greater