Onuma Pond

About Onuma Pond

A freshwater lake 130 m above sea level at the southern foot of Mt. Komagatake. It formed when lava from Komagatake's great eruption in 1640 dammed the rivers. More than 120 islets called nagareyama float in Onuma and Konuma. It became Hokkaido's first quasi-national park in 1958 and, together with Konuma and Junsainuma, a Ramsar Site in 2012. Whooper swans winter here, and mandarin ducks breed.

Sources: Ministry of the Environment, Ramsar Site leaflet: Onuma, Ministry of the Environment, Overview of Quasi-National Parks, Environment Agency of Japan, Lake Survey Report (1993) (sources in Japanese)

Lake data

Area

5.31 km²#15 in Hokkaido

Maximum depth

11.6 m#20 in Hokkaido

Average depth

5.9 m

Surface elevation

129 m

Transparency

2.5 m#15 in Hokkaidoas of the 1991 survey

Origin

Dammed lake

Lake type

Eutrophic

Fresh or brackish

Freshwater

Freezing

Freezes in winter

Unmodified lake

No

Natural park

Onuma Quasi-National Park

Ramsar Convention

Ramsar Site

Lake number

1220number in the national lake survey

Sources: Geospatial Information Authority of Japan, Area Statistics of Prefectures and Municipalities 2026 (as of July 1), Geospatial Information Authority of Japan, Lake Survey (surveyed 1983), Environment Agency of Japan, 4th National Survey on the Natural Environment: Lake Survey Report (1993). Area and depth use newer figures from the Geospatial Information Authority of Japan where available. Origin, lake type, transparency, freezing and unmodified status are as of the 1991 survey.

Themes that include Onuma Pond

• Dammed lakes
• Eutrophic lakes
• Freshwater lakes