SAPPORO -- A government investigation has confirmed that tunnel construction for the shinkansen bullet train line extension to Sapporo caused a nearby river in northern Japan to run dry, a source told the Mainichi Shimbun on Jan. 27.

The Japan Railway Construction, Transport and Technology Agency (JRTT), a government-affiliated organization managing the project, made the determination. This is the first time that the project has been proven to cause the loss of a river. The agency is preparing to discuss compensation for farmers who relied on the river to water their livestock.

The river affected is the Jinja-no-sawa River, a tributary of the Shubuto River flowing through the town of Kuromatsunai in southwestern Hokkaido. Farmers began noticing a significant drop in water levels around the summer of 2023. The river, which had supplied water for livestock for around 40 years, became so depleted that they had to reduce their cattle numbers.

The JRTT reported that there was still water in the river during the spring snowmelt in April 2024, but in May, the flow dropped to just 0.2 cubic meters per minute, and completely dried up in June.

The construction of a 15-kilometer tunnel is underway beneath the Jinja-no-sawa River to extend the Hokkaido Shinkansen Line from Shin-Hakodate-Hokuto Station, which already connects Hokkaido with Shin-Aomori Station on the Japanese mainland. During tunneling, workers encountered significant groundwater flows -- up to 15 cubic meters per minute in some areas -- complicating the process.

To investigate the link between the construction and the river's disappearance, the JRTT began surveys in June 2024. This included mapping underground water distribution, comparing groundwater quality between the tunnel and the river, and locating the places where the river seeps underground, after its flow is restored by rainfall.

By December 2024, the JRTT concluded that groundwater had likely disappeared near the tunnel and that the river's water had been diverted underground into the tunnel. This conclusion was supported by groundwater quality tests at three locations along the tunnel. With no other underground construction in the area, the JRTT attributed the river's drying to the shinkansen project.

Despite these findings, construction continues. As of December 2024, the Uchiura Tunnel still had an average inflow of 6.3 cubic meters of water per minute. Tunnel boring is expected to finish by August 2025, with concrete pouring scheduled for October 2026. The JRTT has indicated a low likelihood of the river recovering even after construction is completed and is preparing compensation for affected farmers.

The agency is also studying the seasonal effects on local plant and animal life and the river's water levels, with a final report expected by fall 2025. A JRTT spokesperson commented, "We will respond carefully to avoid inconveniencing water users."

(Japanese original by Hiroyuki Katano, Hokkaido News Department)