Reservoirs in Hiroshima Prefecture remain at high risk of overflowing after torrential rain pounded western Japan over the weekend.
Hiroshima has about 20,000 reservoirs, the second highest figure in Japan after Hyogo Prefecture.
On Wednesday, 3 municipalities issued evacuation orders because nearby reservoirs were full and the structures were in danger of collapse.
Two of the municipalities lifted the orders after the reservoirs were drained to reduce water levels.
But on Thursday, another municipality issued an evacuation order.
Prefectural officials are inspecting 503 reservoirs with 50 or more houses downstream that would be severely damaged if the structures break.
Officials are urging residents to stay on the alert, and to evacuate immediately if they notice anything unusual, such as water suddenly turning muddy.