Restoration of Kushiro River
Kushiro Swamp, at the downstream of Kushiro River, has precious natural environment. It’s dimension has
decreased due to economic activities around the area; the vegetation has shifted from reeds that live in wet
environment to alder that live in wet and dry environment. Growth of alder is said to be caused by: increasing
sediment inflow to the swamp area due to surrounding land development and straightened streams; and lowered
groundwater level. Kushiro Swamp’s natural environment deterioration is unfavorable for people, as well as for thewild animals, and certain measures to conserve and restore the original environment are required. Based on the river
law revision, Hokkaido Regional Development Bureau has started various efforts in coordination with the relatedorganizations. This is the first case in the country of river administrator’s positive involvement in swamp
conservation.

Key to Restoration¾Winding stream restoration¾

Swamp vegetation control experiment¾

Measures against sediment inflow

Overview of the River
Kushiro River, a class A river originating in Kussharo Lake in Akan
National Park in eastern Hokkaido, flows gently winding through the big
Kushiro Swamp area in Kushiro Plain, into the Pacific Ocean. Its total
length is 154 km and the basin dimension is 2510 km2. The population is
0.18 million, and the estimated flood area population is 71000. Since
salmon and trout run the river and salmon artificial hatching is operated,
it is an important river for natural resource conservation and reproduction.
Kushiro Swamp, located in Kushiro River downstream, is the biggest
swamp in Japan. Its dimension is 20000 ha, 5500 ha of which isregistered as a natural monument and as a designated wetland under theRamsar Convention.
Located near to urban area, the swamp serves as a flood adjuster as well
as scenic and tourism resources. In these fifty years, however, its
dimension has decreased by twenty percent and alder is rapidlyexpanding.
Ministry of Land, Infrastructure and Transport, together with Hokkaido
prefectural government, is investigating multiple concrete measures for:preventing sediment inflow by waterfront forests and sediment-control
pond; enhancing sediment inflow preventive function by forestation;
reviving the swamp; controlling vegetation; and restoring winding river.

KushiroRiver

Project Efforts for Restoration【Winding stream restoration】
In Kayanuma area along Kushiro River, multiple researches and preparatory work are underway aiming at
restoring the original winding river and at restoring the natural habitat.
【Swamp vegetation control experiment】
For conserving the swamp vegetation from the expanding alder, water storage experiment is conducted. The
groundwater level in Yukirihimon area, southwest of Kushiro drainage basin, has been increased in order toresearch its effect on alder.
【Measures against sediment inflow】
In order to prevent sediment inflow into Kushiro Swamp, research and investigation regarding possible measuresin Kuchoro River is in progress, e.g., sediment-control pond and stabilizing river courses.

Source: Hokkaido Regional Development Bureau (http://www.ks.hkd.mlit.go.jp/kasen/sizensai/)“River Restoration” seminar textbook. Foundation for Riverfront Improvement and Restoration.