Sumida, Tokyo International schools: Sumida maintains sister-city relationships with Seodaemun-gu, Seoul, South Korea, and with Shijingshan District, Beijing, China. Sumida, Tokyo , literally "Ink Field", is a special ward located in Tokyo Metropolis, Japan. The English translation of its Japanese self-designation is Sumida City. As of May 1, 2015, the ward has an estimated population of 257,300, and a population density of 18,690 persons per km². The total area is 13.77 km². Sumida is in the northeastern part of the mainland portion of Tokyo. The Sumida and Arakawa are the major rivers, and form parts of its boundaries. Its neighbors are all
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