Lake Hachiro ASI-34

Lat.39.924 Lng.140.022 Alt.0.52
Riparian Nation(s) Japan
Surface Area 46 km2 Mean Depth 4 m Volume 0.14 km3
Shoreline 70 km Catchment Area 823 km2 Residence Time 0.082 yr
Frozen Period Dec-Mar Mixing Type Polymictic Morphogenesis/Dam Remainder of Hachiro-gata (1978)
Related Info/Site

Description

Lake Hachirogata is located approximately 20 km north of Akita City. It used to be the second largest brackish water lake in Japan, having a surface area of approximately 22,000 ha and 12 km (E-W) x 27 km (N-S) in size. The maximum depth of the lake was only 4.5 m, and the lake bottom was rather flat and was covered by mud, allowing easy access to land reclamation by drainage and filling.

The lake reclamation work had long been drawing great interest, attracting a number of proposals which were never implemented. When two Dutch reclamation experts were invited to Japan in 1954 to study the case and two subsequent field study missions, one by the World Bank and the other by FAO, followed the next year, the value of the land reclamation project gained greater publicity. In 1956 the Ministry of Agriculture and Forestry prepared a comprehensive plan for reclamation which began to be implemented in 1957.

The pumping for draining started in November 1963 at the central reclamation site, and the entire reclamation work was completed in 1966. The newly established Ogata Village had the first batch of migrating farmers in 1968, and 580 families settled in the village by the fifth migration. Today there are 585 families, including those who were transferred in after being displaced by the construction of Tamagawa Dam, which are engaged in the first model farming project in Japan.

The land reclamation project of Lake Hachirogata has been approximately 78% completed to date, and there is only 4,564 ha of water surface set aside for water channels and flow regulation purposes. There are some 20 rivers and streams flowing into the lake and the freshwater drawn out from the now converted freshwater lake is used for irrigation at Ogata Village and other nearby settlements. The irrigation water is drawn from 19 intake points and the drainage water is discharged to Hachirogata through major artery drainage channels after being pumped up at the south and north pumping stations. A salt water barrier has been constructed at the outlet of the regulating reservoir through which water is discharged intermittently out to the Japan Sea. The lake water is also used for drinking and fishery and the lake front open spaces are being developed for various citizen recreational activities including picnicking, bird-watching and hunting, as well as for tourism promotion activities.

The completion of the land reclamation project in March 1978 ensued gradual eutrophication of the lake. In December 2007 the lake was appointed as the eleventh designated lake based on the Law Concerning Special Measures for Preserving Lake Water Quality. Akita Prefectual Government drew up the long term vision which describes the desired state of the lake in 2026. Aiming toward the goal, the current Phase II Water Quality Conservation Plan covers the period from 2013 to 2018. (1987, revised in 2018)

Photo of Lake Hachiro
Photo: Ogata Village Office