The Sonthi River (Thai: ลำสนธิ, rtgs: Lam Sonthi, [lam sǒntʰíʔ]) is a tributary of the Pa Sak River. It originates at the Ruak and Phanghoei mountains in the border area of Lam Sonthi district, Lopburi province and Si Thep, Phetchabun province. The river flows southward as the backbone of Lam Sonthi district and joins with the Phaya Klang River from Muak Lek district, Saraburi province. Then the river flows ahead to west and tributes the Pa Sak River in Chai Badan. It is 70 kilometres (43 mi) long.
References
Sonthi River Wikipedia(Text) CC BY-SA