The Ryusai Ikkan Waterway uses water from generating electricity at Minakata Power Plant in Nakagawa Village, which draws water from Minakata Dam (also called Kise Dam) in Komagane City, to irrigate about 700 hectares (1,730 acres) of farmland along the right bank of the Tenryu River in Iida City, Matsukawa Town, and Takamori Town. Sluice gates were put on the Tenryu River in 8 places until the 1930’s, but the monetary and labor cost of replacing them when they were washed away with every flood was enormous. In 1948, government enterprise started large-scale renovations, and it came to look as it does now.
Of its roughly 24 km length, only about 4 km are above ground, with the other 20 km going through mountains.
Completed in 1963, Kegasawa Aqueduct is an aqueduct straddling the Kegasawa River from Matsuo to Dashina in Iida City. You can walk on a walkway on top of the canal. And there are places where you can tell the canal passes below Suzuoka Castle and Matsuo Castle.