Lake Biwako

Country/territory: Japan

IBA Criteria met: A4i, A4iii (2004)
For more information about IBA criteria please click here

Area: 72,224 ha

Wild Bird Society of Japan
Most recent IBA monitoring assessment
Year of assessment Threat score (pressure) Condition score (state) Action score (response)
2015 high near favourable high
For more information about IBA monitoring please click here

Site description
Lake Biwako is 670 km2 and the largest lake in Japan. In addition to Northern Lake (613 km2 - average depth of 43 m) and Southern Lake (57 km2 - average depth of 4 m), which are divided by Biwakoohashi Bridge, there are many shallow marsh grounds called Naiko (inner lake) scattered around Lake Biwako, and they form habitats for wildlife connecting each other. The environmental elements are divided into two parts, a deep and vast offshore area and a shallow water zone along the coastline. The zone is rich in environment with aquatic plants such as Phragmites australis communities, sand beaches, rocky coasts and artificial banks. Surrounding areas are also agricultural fields, forests and urban areas. About 460 large and small rivers flow into Biwako, and sandbanks are well developed at the mouths of large rivers such as the Azumigawa river, the Anegawa river, the Aichigawa river and the Yasugawa river. There are five islets in the lake, Okishima, Chikubujima, Takeishima, Okinoshiroishi and the artificial Kihan-to.

Recommended citation
BirdLife International (2022) Important Bird Areas factsheet: Lake Biwako. Downloaded from on 16/08/2022.