The Union Street undercrossing in The Dalles will be closed at times until the end of next week due to a high Columbia River water levels overtopping its banks and causing water at the undercrossing to be deep enough to be hazardous to vehicles.  According to the Army 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.  Union Street northbound will be closed to through traffic at the railroad tracks when necessary, and will be completely closed north of the Hattenhauer access road at 111 West First Street.  Intermittent access to Lewis and Clark Festival Park will be open as river levels allow.  Approaching the undercrossing from the west side, West First Street will be closed to through traffic at Terminal Way and will be completely closed beyond the employee access to the Oregon Cherry Growers facility.  Motorists are encouraged to use Webber Street as an alternate route to access West First Street during times the underpass is closed.