The Union Street Undercrossing in The Dalles has been closed to all traffic until further notice due to the high Columbia River level, which is causing water at the undercrossing to be deep enough to be hazardous to vehicles, bicyclists and pedestrians.  According to the Corps of Engineers, which operates Columbia River dams, the high water level of the Bonneville Pool is necessary for flood control due to recent rain and snow melt.  When necessary, Union Street northbound will be closed to through traffic at the railroad tracks, and will be completely closed north of the Hattenhauer access road at 111 West 1st Street.  Intermittent access to Lewis and Clark Festival Park will be open as river levels allow.  Approaching the undercrossing from the west side, West 1st Street will be closed to through traffic at Terminal Way and will be completely closed beyond the employee access to the Oregon Cherry Growers Riverside facility.  Motorists, bicyclists and pedestrians are encouraged to use Webber Street as an alternate route to access West 1st Street and the west section of the Riverfront Trail during times the underpass is closed.