Lake Abashiri

Lake Abashiri 網走湖
A view from Mount Tento (July 2013)
Lake Abashiri 網走湖
Location	Abashiri, Hokkaidō, Japan
Coordinates	43°58′N 144°10′E
Lake type	Dimictic
Primary inflows	Abashiri River and Memanbetsu River
Primary outflows	Abashiri River
Catchment area	1,380 km2 (530 sq mi)
Basin countries	Japan
Surface area	33 km2 (8,200 acres)
Average depth	7.2 m (24 ft)
Max. depth	16.1 m (53 ft)
Water volume	0.2327 km3 (0.0558 cu mi)
Residence time	0.43 years
Shore length1	44 km (27 mi)
Surface elevation	0.4 m (1.3 ft)
Frozen	December to April
Islands	none
Settlements	Abashiri
1 Shore length is not a well-defined measure.

Lake Abashiri (網走湖, Abashiri-ko) is a meromictic lake in Abashiri, Hokkaidō, Japan. It is located in Abashiri Quasi-National Park. The Abashiri and Memanbetsu Rivers flow into the lake. Water exits the lake through the Abashiri River again and flows 7 kilometres (4.3 mi) to the Sea of Okhotsk.

History and formation

From core samples taken from the lake bed, the lake basin appears to have first formed some 20,000 years ago during the last period of glaciation. During the last 6000 years, the Abashiri River carved out the lake bed. Artifacts from the Jōmon period have been found in the area around the Memanbetsu River. In modern times, the course of the Abashiri River has been straightened to provide for irrigation resulting in a serious siltation problem for the lake.

Freezing and salinity

Lake frozen over (February 2004)

The lake freezes over from December to April with ice up to a meter thick. The reduced inflow of water during the winter season causes saltwater to flow upstream from the Sea of Okhotsk and into the lake. This influx of saltwater has created a layer of saline water with 10,000 ppm of chlorine, 10 metres (33 ft) below the surface of the lake with a freshwater upper layer that makes up 46% of the volume of the lake.

Fauna

The wakasagi (Hypomesus nipponensis) and corbicula (Corbicula japonica) are common in the lake.