A fl ood control facility with an extensive reed bed, an excellent habitat for 700 species of plants Watarase-yusuichi Low Moor, Artifi cial Wetland Geographical Coordinates: 36°14’N, 139°41’E / Altitude: 8-23m / Area: 2861ha /Major Type of Wetland: Low moor, artifi cial wetland / Designation: National Wildlife Protection Area, River Area / Municipalities Involved: Koga City, , City, Oyama City and Nogi Town, , Itakura Town, , Kazo City, / Ramsar Designation: July 2012 / Ramsar Criteria: 1

control along with a number of dams in the upstream of the , a primary river that runs through the Kanto plains. The excess fl ood water from the three rivers, Watarase-gawa, Omoi-gawa and Uzuma-gawa, is stored in this basin tem- porarily so as not to affect the trunk of the Tone river. Wetland Conservation and Basic Plan for Restoration: A Committee for Wetland Conservation and Restoration of Watarase-yusuichi was established in 2002 in order to improve the fl ood control function as well as to pro- mote wetland conservation and restoration of this basin. The committee formulated a Lake Yanaka-ko plan: “Basic Plan for Wetland Conservation and Restoration of Watarase-yusuichi” in 2010. The objective of this plan is restor- ing the deteriorated wetland environment by excavating the places affl icted by nega- tive factors such as alien species to restore a habitat for diverse fauna and fl ora. Wet- land conservation and restoration in this area is going to be promoted based on this plan while taking consideration for the conservation of the existing good environ- ment and improvement of the fl ood control function. An extensive reed bed Eastern Marsh Harrier Contact Information: Koga City Offi ce http://www.city.koga.ibaraki.jp/ General Overview: Watarase-yusuichi supports a habitat for Tochigi City Offi ce Watarase-yusuichi is a retarding basin many species. More than 700 plant spe- http://www.city.tochigi.lg.jp/ located roughly in the center of Kanto cies have been recorded here including Oyama City Offi ce plains. It is a facility to store water for over 50 species recognized in the red list http://www.city.oyama.tochigi.jp/ daily use and to retain the river overfl ow of the Ministry of the Environment, such Nogi Town Offi ce temporarily to prevent fl ooding in the as Ophioglossum namegatae and Viola http://www.town.nogi.tochigi.jp/ river basin. The area has been affl icted by raddeana. One hundred and forty species Itakura Town Offi ce repeated heavy fl oods and still faces the of birds have been recorded. From spring http://www.town.itakura.gunma.jp/ risk of another fl ood even now. to summer, it is a breeding ground for Kazo City Offi ce During the Meiji period, approximately some grassland birds such as Great Reed http://www.city.kazo.lg.jp/ 100 years ago, contaminated water from Warblers and Zitting Cisticolas, while in the spilled out fre- winter, it is a wintering ground for thou- Rwy Rd. quently at the time of fl oods and damaged sands of ducks, many buntings and some Watarase Uzuma River a large area in the lower reaches of the riv- Eastern Marsh Harriers which is cited as River ers. As it became a big societal problem, “endangered” in the red list of the Minis- the government decided to abolish a vil- try of the Environment. Omoi Fujioka River lage called Yanaka to construct a retarding A Vital Point for Flood Control of the Tone Sta. basin to control the fl ooding and mining River System: Itakura Watarase- pollution. This facility was built on the The fl ood caused by River yusuichi sacrifi ces of many people. in 1947 brought about catastrophic dam- Nogi Sta. There are three regulating reservoirs age to many places in the Kanto Plains. enclosed by embankments. The reservoirs In order to control such disasters, river and the river beds are covered with one of improvements including the construction the largest reed beds in , the main of upstream dams and river channels were Yanaka-ko Koga Sta. island of . carried out in many rivers such as the Tone Shinkoga Sta. A Rich Fauna and Flora: River and the . Watarase- Watarase River Rwy Rd. The diverse wetland environment of yusuichi has an important role of fl ood

30 RAMSAR SITES in JAPAN