UPDATE (As of 10:30 a.m., Feb. 27): The Malheur River at Vale has dropped below the Minor Flooding stage, according to the Malheur County Sheriff's Office. The Oregon Department of Transportation has reopened U.S. 20.
UPDATE (Wednesday, Feb. 26): All lanes of U.S. Highway 20 remain closed between Juntura (milepost 190) and Harper due to flooding. Drivers should check TripCheck.com for updates before driving in the area.

Tuesday, February 25: U.S. Highway 20 is closed between Juntura (milepost 190) and Harper (milepost 223) due to flooding from the Malheur River.

That's according to the Oregon Department of Transportation, and in a post last night they said that they would assess the situation this morning.
However, a caller this morning has reported intense flooding around her house outside Harper along Hwy 20 and about 50 yards from the Malheur River.
She said that her house is elevated from the flood level, but houses below her are dealing with flooding and that water levels are still rising.