Arakawa, Tokyo Arakawa, Tokyo Arakawa has sister-city relationships with Donaustadt in Vienna, Austria, and with Corvallis, Oregon, U.S. Domestically, it has similar relationships with nine cities, towns and villages. As of May 1, 2015, the ward has an estimated population of 208,763, and a population density of about 20,550 persons per km². The total area is 10.16 km². Arakawa is in the northeastern part of Tokyo. The shape is long and narrow, stretching from west to east. The Sumida River forms the northern boundary. The ward is surrounded by five other special wards. To the north lies Adachi; to the west, Kita;
Arakawa River (Fukushima) ineffective, and the river continued to periodically flood, culminating in a large-scale flood on August 5th, 1986. In 2004 the Arakawa River's flood control system was completely overhauled, and 13 new check dams were built along the main river and numerous other dams built on its tributaries. In 2008 the Agency for Cultural Affairs designated the Arakawa First Check Dam as a Registered Tangible Cultural Property. In 2007 the Arakawa River tied with six other rivers for having the best quality river water in country based on biochemical oxygen demand tests conducted by the Ministry of Land, Infrastructure, Transport and