Lachen River

{{Use dmy dates|date=August 2019}}

{{Infobox river

| name = Lachen River

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| subdivision_name1 = India

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| source1 = Himalayas

| source1_location = Himalayas, Sikkim, India

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| mouth = Teesta River

| mouth_location = Mangan district, Sikkim, India

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File:Confluence of the Lachen and Lachung c.pngs c. 1885]]

The Lachen River is a tributary of the Teesta River in the state of Sikkim, India. It is one of the two main tributaries of the Teesta along with the Lachung River, which rise on opposite sides of the Donga Range in neighbouring Bhutan{{cite book|title=Memoirs of the Geological Survey of India|url=https://books.google.com/books?id=tnKNWMMc0VQC|year=1912|publisher=By order of the Governor-General of India|page=8}} and converge in Chungthang in the North Sikkim district.{{cite web|url=http://sikkim.nic.in/sws/poi_nor.htm|title=North Skikkim|publisher=National Informatics Centre|accessdate=12 August 2015|archive-url=https://web.archive.org/web/20150821103458/http://sikkim.nic.in/sws/poi_nor.htm|archive-date=21 August 2015|url-status=dead}}