NEW : Fishing and tourism grind to a halt in many places . U.S. wildlife official warns of `` multi-decade impact '' from spill . Dispersants to be applied near spill site Saturday , BP says . TL;DR NEW
NEW : Fishing and tourism grind to a halt in many places . U.S. wildlife official warns of `` multi-decade impact '' from spill . Dispersants to be applied near spill site Saturday , BP says . President Obama announces he will visit the spill area on Sunday .