Abstract
Town A in Fukushima prefecture ordered the residents to evacuate just after the accident at Fukushima Daiichi Nuclear Power Plant. The order was canceled in the next year and the residents started to return. In parallel, a lot of workers for recovery of the affected areas have been staying in the town, resulting in 1.5 times larger population than before the accident. We found the tap water supply has increased and it is approaching to the limit of the existing water treatment plant. We also discussed the effect of dormitories for the immigrated workers on water environment based on the published reports and analysis of water samples, which revealed that septic tanks for the dormitories worked well and discharged water with low BOD. The pollution load estimated from the quality of discharged water was small enough and negligible compared to that in the receiving river. As found in this case, evacuation of residents after nuclear power normally continues for a longer time and involves a wider area than other natural disasters. It is recommended to prepare for accidents of nuclear power plant by sharing tap water supply with neighbor towns, finding desirable location of dormitories for workers and temporary houses, and so on.
