Greenpeace surveys the downstream contamination of river systems and estuaries in Fukushima prefecture. The Niida River flows from heavily contaminated forests and mountains in Iitate and enters the Pacific Ocean at Minami-Soma, 10-40km north of the Fukushima Daiichi nuclear plant. Due to the long half life of radionuclides released from the March 2011 accident, including Cesium-137, the rivers of Fukushima are acting as a transport mechanism for downstream contamination. During significant rainfall events, typhoons, and spring snowmelt, the stocks of radiocaesium in forests, hillslopes and floodplains can be remobilized and contaminate areas downstream – including those that did not receive fallout from the radioactive plumes, as well as areas that have already been decontaminated.