Yom River

Yom River
Yom River in Mueang Phrae District, Phrae Province
Country	Thailand
Tributaries
- right	Ngao River
Source
- location	Bun Yuen village, Pong district, Phi Pan Nam Range, Phayao Province
- elevation	347 m (1,138 ft)
Mouth	Nan River
- location	Chum Saeng district, Nakhon Sawan province
- elevation	28 m (92 ft)
Length	787 km (489 mi)
Basin	24,047 km2 (9,285 sq mi)
Discharge	for Nakhon Sawan
- average	103 m3/s (3,637 cu ft/s)
- max	1,916 m3/s (67,663 cu ft/s)
Map of the Chao Phraya River drainage basin showing the Yom River

The Yom River (Thai: แม่น้ำยม, rtgs: Maenam Yom, IPA: [mɛ̂ːnáːm jom]) is the main tributary of the Nan River (which itself is a tributary of the Chao Phraya River). The Yom river has its source in the Phi Pan Nam Range in Pong district, Phayao Province, Thailand. Leaving Phayao, it flows through Phrae and Sukhothai as the main water resource of both provinces before it joins the Nan River at Chum Saeng district, Nakhon Sawan Province.

Tributaries of the Yom include Pong, Ngao, Ngim, Sin, Suat, Pi, Mok, Phuak, Ramphan, Lai, Khuan and Kam Mi Rivers.

The Yom river and its tributaries drain a total area of 24,047 square kilometres (9,285 sq mi) of land (called the Yom Basin) in the provinces of Sukhothai, Phitsanulok, Phichit, Phrae and Lampang. The Yom Basin is part of the Greater Nan Basin and the Chao Phraya Watershed.