The Teruizeki irrigation canals were excavated over 800 years ago, around the year 1180. Traces were originally found during the excavation project of the historical monuments and sites of Hiraizumi which achieved UNESCO world heritage site status in 2011. The irrigation system itself is believed to have significant influence on the culture at the time.
Over the decades, repairs and developments were made to the canal system by the rulers of the land, to countermeasure draughts. Years of developments and changes have contributed to the fully operating Teruizeki irrigation system which is still in use today.
The irrigation system consists of a variation of weirs, regulating gates, unlined canals, stone canals, concrete canals, tunnels, elevated fumes, pipe bridges and also uses inverted siphons. The combined total length of the 8 canals is 64km which irrigate 1,073 ha of farmland.
The significance of the Teruizeki irrigation canals in local agriculture, as well as its importance in regional development which contributes to the nature, scenery and culture of the area were recognized in 2006 to be inducted into the best 100 irrigation canals in Japan. The canals are also introduced as a case study in the Japanese curriculum. Elementary school children are taught the history of the canals, and also participate in field trips to explore the tunnels.
Teruizeki irrigation system has supplied water to the grounds of the four famous temples which make up the historical sites of Hiraizumi, which achieved UNESCO world heritage site status in 2011. The multifunctional agricultural canals have an outstanding universal significance even today. The Teruizeki irrigation system shall be preserved long into the future, by relying on strong community togetherness to help maintain the flow of the water.