, also known locally as is a brackish-water lagoon-type estuary located in the city of Goshogawara in Aomori Prefecture,

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. It is the third-largest lake in Aomori Prefecture, after Lake Towada and Lake Ogawara, with a shoreline of and a maximum depth of 3 meters.

Etymology

Per the Goshogawara city tourist bureau, the lagoon is called Lake Jusan because different rivers flow into it. However, other sources state that the name comes from the

Ainu language Ainu (, ), or more precisely Hokkaido Ainu, is a language spoken by a few elderly members of the Ainu people on the northern Japanese island of Hokkaido. It is a member of the Ainu language family, itself considered a language family isolate ...

word "To Sam", meaning the "shoreline of a lake".

Hydrology

The primary inflow to Lake Jūsan is the

Iwaki River The is a river that crosses western Aomori Prefecture, Japan. It is in length and has a drainage area of . Under the Rivers Act of 1964 the Iwaki is designated as a Class 1 River and is managed by the Japanese Ministry of Land, Infrastructure, ...

. Several small rivers also flow into the lagoon. The only outflow of the lagoon is to the Sea of Japan at the northwest corner of the lake, opposite to the mouth of the Iwaki River.

Geology

Lake Jūsan was formed after the end of a glacial period about 7,000 years ago. The retreating glaciers left behind sandy deposits that divided the estuary from the Sea of Japan. After five hundred years a lake had formed. However, the lake would be filled in by sediments deposited by the

, causing it to become more shallow and brackish.

History

The primary source of the lagoon, the Iwaki River, supported numerous villages as early as the

Jōmon period The is the time in Japanese history, traditionally dated between 6,000–300 BCE, during which Japan was inhabited by a diverse hunter-gatherer and early agriculturalist population united through a common Jōmon culture, which reached a c ...

(14,000 – 300 BCE) as evidenced by numerous shell mounds. The river was revered as the "mother of the Tsugaru Plain" throughout its early history. The Iwaki River region, located in the vast northern

Mutsu Province was an old province of Japan in the area of Fukushima, Miyagi, Iwate and Aomori Prefectures and the municipalities of Kazuno and Kosaka in Akita Prefecture. Mutsu Province is also known as or . The term is often used to refer to the comb ...

, did not come under the control of the central government until the late Heian period (794 – 1185) The

Northern Fujiwara The Northern Fujiwara (奥州藤原氏 ''Ōshū Fujiwara-shi'') were a Japanese noble family that ruled the Tōhoku region (the northeast of Honshū) of Japan during the 12th century as their own realm.

clan, based in Hiraizumi in present-day

Iwate Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture at , with a population of 1,210,534 (as of October 1, 2020). Iwate Prefecture borders Aomori Prefecture to the north, Akita Prefectur ...

, controlled the trade with the Asian continent and Hokkaido via the

Port of Tosa A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as ...

, located on the western shore of the lake. Despite the loss of control of much of Japan later in the Heian period, the court maintained some level of military presence in Mutsu. This control ended when the Northern Fujiwara were conquered by Minamoto no Yoritomo (1147 – 1199) and clans of the

Kantō region The is a geographical area of Honshu, the largest island of Japan. In a common definition, the region includes the Greater Tokyo Area and encompasses seven prefectures: Gunma, Tochigi, Ibaraki, Saitama, Tokyo, Chiba and Kanagawa. Slight ...

, and the Iwaki River region came under the direct control of the Kamakura shogunate. By the mid-Kamakura period the Andō clan ruled the area, and Fukushima Castle was built on the north shore of the lake. The Andō controlled trade with the

Ainu Ainu or Aynu may refer to: *Ainu people, an East Asian ethnic group of Japan and the Russian Far East *Ainu languages, a family of languages **Ainu language of Hokkaido **Kuril Ainu language, extinct language of the Kuril Islands **Sakhalin Ainu la ...

via Tosaminato. Some records indicate that Port Tosa was destroyed in an enormous tsunami in 1340; however, historical records for this period are scarce and lack veracity. What is more certain is that the Andō were defeated by the Nanbu clan in 1442, and the port fell rapidly into disuse after that date. During the Edo period, the port was rebuilt as the point where rice harvested in the Hirosaki Domain was exported to the Osaka, but it never regained its former prosperity and fell into disrepair again after the proliferation of railroads during the Meiji period. The ruins of Port Tosa are preserved today as a National Historic Site. The folk song and dance pays tribute to the lagoon and the port. Economically, Lake Jūsan is noted today for its production of ''shijimi'' clams.

References

External links