The U.S. Army Corps of Engineers reported a thrust hub cooling water pipe broke on Thursday, spilling up to 200 gallons of oil into the Columbia River at The Dalles Dam.  The equipment is part of a fish unit turbine designed to provide attraction water for migrating fish.  A statement from the Corps indicated the turbine is now isolated from the river.  Corps technicians are assessing how much oil actually spilled into the river, as some of the 200 gallons may be contained in a draft tube or collection channel within the dam.  Operations Division chief Dwane Watsek says booms and skimmers were used to contain and clean up the oil, and the unit will remain out of service and isolated from the river until technicians assess and repair it.