The is a
breakwater and
artificial island
An artificial island or man-made island is an island that has been Construction, constructed by humans rather than formed through natural processes. Other definitions may suggest that artificial islands are lands with the characteristics of hum ...
located in
Tokyo Bay
is a bay located in the southern Kantō region of Japan spanning the coasts of Tokyo, Kanagawa Prefecture, and Chiba Prefecture, on the southern coast of the island of Honshu. Tokyo Bay is connected to the Pacific Ocean by the Uraga Channel. Th ...
, adjacent to the
Tokyo Gate Bridge.
History

The Central Breakwater was first constructed in 1973 and has been used as a site for waste disposal from Tokyo since then, forming two
artificial island
An artificial island or man-made island is an island that has been Construction, constructed by humans rather than formed through natural processes. Other definitions may suggest that artificial islands are lands with the characteristics of hum ...
s in Tokyo Bay known as the and the . The islands had a combined area of 377 hectares in 2011 and are expected to ultimately reach an area of 989 hectares.
Jurisdiction dispute
Jurisdiction over the Central Breakwater islands was disputed between the
special wards of
Koto and
Ota for 4 decades. Under Japanese law, any boundary dispute may be submitted to the prefectural government (in this case, the Tokyo metropolitan government) for resolution; a similar dispute with regard to the nearby
Odaiba and
Ariake area was resolved in 1982 by splitting the area between the three special wards that claimed it.
Koto has argued that the garbage used to create the landfill was hauled through Koto and that making the island part of the special ward would repay residents for their trouble, while Ota has argued that the site of the breakwater was historically used by Ota-based ''
nori'' cultivators, and that the island should be managed in coordination with nearby
Haneda Airport (which is part of Ota). The dispute is mainly considered an issue of brand image; jurisdiction over the island offers little practical benefit to the special wards, as fixed asset taxes on real estate are collected by the metropolitan government.
On October 3, 2019
Tokyo District Court ruled 79.3% of the Central Breakwater landfills to
Kōtō Ward and 20.7% to
Ōta Ward for multiple decades. Ota Ward stated that it won't appeal the ruling. Thus the 40 year dispute was closed.
From December 17 to January 31, 2020 the public made 532 proposals for the town name of the west side to be incorporated in Ota Ward. On 1 June 2020, Reiwajima (令和島) became the official name. The east side of Koto Ward uses the name Sea Forest (海の森) which they were accustomed to.
2020 Summer Olympics
The Central Breakwater is one of the planned venues for the
2020 Summer Olympics
The officially the and officially branded as were an international multi-sport event that was held from 23 July to 8 August 2021 in Tokyo, Japan, with some of the preliminary sporting events beginning on 21 July 2021. Tokyo ...
. The Inner Landfill will host the Sea Forest Cross-Country Course for equestrian events, while the Outer Landfill would have hosted the Sea Forest Mountain Bike Course but was eventually moved to
Izu, Shizuoka
is a Cities of Japan, city located in central Izu Peninsula in Shizuoka Prefecture, Japan. , the city had an estimated population of 30,678 in 13,390 households, and a population density of 84 persons per km2. The total area of the city was .
...
. The waterway between the two islands, named
Sea Forest Waterway, will be used for rowing and kayaking events. The venues will be maintained as recreational areas after the Games.
References
{{Olympic venues equestrian
Breakwaters
Artificial islands of Japan
Venues of the 2020 Summer Olympics
Olympic equestrian venues
Tokyo Bay
Internal territorial disputes of Japan