Kushiro River Restoration

The Kushiro River on the northern Japanese island of Hokkaido used to meander across a vast area of green hills and rural communities, through the Kushiro wetlands, the country’s largest and home to some 2,000 species of wildlife, before disgorging into the blue waters of the Pacific Ocean at its port city namesake. Then something happened.

In a country with one of the highest population densities on the planet, maximizing the use of every available inch of land makes perfect sense. In the 1980s, environmental considerations played second fiddle to economic development. Engineers straightened the Kushiro, channelizing the river in the name of flood prevention and economic development. The latter took the form of work for the engineers and laborers employed on the project, reclaiming the land taken up by the natural bends of the river that would otherwise lie underutilized, and transforming the area into a neat and efficient grid.

The Kushiro wetlands, seen as a useless piece of swamp land, were planned to be drained and turned into a home for factories and other commercial buildings, creating employment for the region and adding another cog to Japan’s economic machine. Thankfully, the engineers never got around to competing this part of the project. The sad postscript is that nature is progressing the transition for them. An unintended consequence of human meddling in the natural course of the Kushiro is that the wetlands are drying up. At risk is a wonderful diversity of wildlife, which includes the red-crowned crane and Japan’s largest freshwater fish, the huchen.

Straightened rivers might reduce the risk of flooding, but they flow faster and deeper and serve as a conveyor belt to transport sediment from their catchment areas to their estuaries and the sea. Reduced or gone is the seasonal addition of nutrient rich sediments to flood plains and flow into ground water reserves. While the Kushiro was spared the full concrete treatment of its northern neighbor, the Pereke River, it has also lost its natural appeal and now more closely resembles a canal or irrigation channel than a river.

It may not be too late for the Kushiro. Work commenced in 2007 to restore some of the river’s natural shape. It will not restore the entire river and potentially creates new problems. Opponents argue that a number of upstream projects are releasing excessive amounts of sediment that could hasten the demise of the Kushiro wetlands by eventually burying them. Cynics argue that it just an employment creation project in a similar vein to the initial straightening.

Whether the project to restore the Kushiro will achieve its objectives is uncertain. Without a whole river approach, from source to sea, the outlook for the Kushiro’s future remains bleak. At best, the restoration efforts provide the possibility of improvement and some hope for the future.


“Forced to run straight, a river must now twist”, New York Times – November 7, 2007

“Kushiro River Embankment: Earthquake Disasters and Restoration”, Hokkaido Development Board – October 22, 2004

ARRN: Kushiro River, Asia River Restoration Network – July 13, 2006