Koito River

Koito River
Koito River in winter, Kimitsu, Chiba
Native name	小糸川
Country	Japan
Basin features
Main source	Mount Kiyosumi, Kimitsu
River mouth	Tokyo Bay, Kimitsu 0 m (0 ft)
Basin size	148.7 km2 (57.4 sq mi)
Physical characteristics
Length	82 km (51 mi)

Coordinates: 35°21′4″N 139°51′21″E / 35.35111°N 139.85583°E / 35.35111; 139.85583

The Koito River (小糸川, Koito-gawa^?) is a river in Futtsu and Kimitsu, Chiba Prefecture, Japan. The river is 82 kilometers (51 mi) in length and has a drainage area of 148.7 square kilometers (57.4 sq mi). The Koito is the third-longest river in Chiba Prefecture, and under the Rivers Act of 1906 the Koito is designated as a Class 2 River. The name of the river in Japanese is a combination of two kanji characters, the first meaning “little”, and the second meaning “thread”.

The Koito River originates from a deep valley in forests around Mount Kiyosumi in the Bōsō Hill Range. The river cuts through the Kazusa Hill Range, a smaller part of the Bōsō Hill Range, and in its upper part, meanders northwest. The Koito creates picturesque ravines throughout the Bōsō Hill Range, and passes by Mount Karasuba and Mount Kiyosumi. The middle and lower parts of the Koito feature fluvial terraces. Extensive land reclamation was carried out near the mouth of the river, and this land was used to build the Nippon Steel Kimitsu Works. The Kimitsu Works sits on the north bank of the Koito River where it empties in Tokyo Bay.