Shiogō Dam
Encyclopedia
The is a dam
on the main stream of the Ōi River
, located in the town of Kawanehon
, Haibara District
, Shizuoka Prefecture
on the island of Honshū
, Japan
.
.
The Shiogō Dam and neighboring Sasamagawa Dam
were constructed to provide water for the 58,000 KW Kawaguchi Hydroelectric Plant built by the Shimada city
government. Construction work began in 1958 and was completed by 1961. Although styled as a “dam”, the structure is in fact a weir
, as it does not meet the 15-meter height stipulated in Japanese construction regulations to qualify as a "dam".
and Japanese dace, which the dam replaced with an area of stagnant, algae-polluted water with an offensive smell. The dam also reduced the amount of sand and silt reaching the mouth of the Ōi River, thus further contributing to shoreline erosion. Legal efforts by local municipalities and landowners to recover water rights over the Ōi River and force the dismantling of the dam have consistently failed in courts.
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
on the main stream of the Ōi River
Oi River
The is a river in Shizuoka Prefecture, Japan.-Geography:The Ōi River flows from the Akaishi Mountains, the branch of the Japanese Southern Alps which form the border between Shizuoka, Nagano and Yamanashi prefectures. These mountains, with peaks ranging from 2000–3000 meters, are characterized by...
, located in the town of Kawanehon
Kawanehon, Shizuoka
is a town located in Haibara District, Shizuoka, Japan. As of February 2010, the town has an estimated population of 8,253 and a density of 16.8persons per km². The total area was 496.72 km².-Geography:...
, Haibara District
Haibara District, Shizuoka
Haibara is a district located in Shizuoka, Japan.As of 2004, the district has an estimated population of 95,091 and a density of 126.88 persons per km²...
, Shizuoka Prefecture
Shizuoka Prefecture
is a prefecture of Japan located in the Chūbu region on Honshu island. The capital is the city of Shizuoka.- History :Shizuoka prefecture was formed from the former Tōtōmi, Suruga and Izu provinces.The area was the home of the first Tokugawa Shogun...
on the island of Honshū
Honshu
is the largest island of Japan. The nation's main island, it is south of Hokkaido across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyushu across the Kanmon Strait...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.
History
The potential of the Ōi River valley for hydroelectric power development was realized by the Meiji government at the start of the 20th century. The Ōi River was characterized by a high volume of flow and a fast current. Its mountainous upper reaches and tributaries were areas of steep valleys and abundant rainfall, and were sparsely populated. From the 1930s through the 1960s, numerous concrete gravity dams had been constructed on the main flow of the Ōi River, and to its various tributary streamsTributary
A tributary or affluent is a stream or river that flows into a main stem river or a lake. A tributary does not flow directly into a sea or ocean...
.
The Shiogō Dam and neighboring Sasamagawa Dam
Sasamagawa Dam
The is a dam on the Sasama River, a tributary of the Ōi River, located on the border of the city of Shimada and the town of Kawanehon, Shizuoka Prefecture on the island of Honshū, Japan.-History:...
were constructed to provide water for the 58,000 KW Kawaguchi Hydroelectric Plant built by the Shimada city
Shimada, Shizuoka
is a city in Shizuoka Prefecture, Japan. As of February 2010, the city has an estimated population of 100,846 and a population density of 319 persons per km². The total area is 315.88 km².-Geography:...
government. Construction work began in 1958 and was completed by 1961. Although styled as a “dam”, the structure is in fact a weir
Weir
A weir is a small overflow dam used to alter the flow characteristics of a river or stream. In most cases weirs take the form of a barrier across the river that causes water to pool behind the structure , but allows water to flow over the top...
, as it does not meet the 15-meter height stipulated in Japanese construction regulations to qualify as a "dam".
Controversy
The Shiogō Dam was built in an area where the Ōi River made a number of turns over swift rapids. The area was a popular fishery for ayuAyu
The or sweetfish, Plecoglossus altivelis, is an amphidromous fish, the only species in the genus Plecoglossus and in family Plecoglossidae. It is a relative of the smelts and is placed in the order Osmeriformes...
and Japanese dace, which the dam replaced with an area of stagnant, algae-polluted water with an offensive smell. The dam also reduced the amount of sand and silt reaching the mouth of the Ōi River, thus further contributing to shoreline erosion. Legal efforts by local municipalities and landowners to recover water rights over the Ōi River and force the dismantling of the dam have consistently failed in courts.