Roads connecting Chiang Khong and Chiang Saen were also inundated, including Highway 1020.
Chiang Khong district chief Thassanai Suthapoj said three villages in Tambon Sathan and six in Tambon Sri Donchai were affected and two schools remained closed.
Chiang Saen officials were meanwhile helping affected residents of Ban Mae Aeb, Tambon Ban Saew, where 20 houses were flooded.