Utilization of Water Resources
The water of Lake Towada is also used for power generation. The water is conveyed through a mountain driving channel from the Intake of Aobuna downstream to the Towada Power Plant. There are no major rivers flowing into Lake Towada, but the lake has its own source of water from rain and snow stored in beech forests on the outer rim. More water volume than the lake inflow amount is needed for power generation, so the lowering of the water level is inevitable. Thus, water taken in by each tributary flowing into the Oirase Stream (in the middle of the water conveyance from Lake Towada to the Power Plant) is sent back to Lake Towada in aims to help the water level recover. Additionally, a regulating gate at Nenokuchi, located about 300 m downstream from Lake Towada, controls the inflow of the stream. Even though the landscape of Oirase Stream was originally created by a stable aquatic environment in which flooding has been difficult to occur; explanations such as “the water gate controls water quantity, that’s why Oirase Stream seldom floods” are often made. However, there has been no case example in the past in which the water gate prevented flooding in the stream. The water gate is merely a facility for the Power Plant. In other words, the water gate merely discharges water for sightseeing purposes in measures to deal with damage to the landscape caused by falling water levels. The water used for power generation at Towada Power Plant is conveyed via Tateishi and Horyo Power Plants, respectively, and finally is utilized as irrigation water.