The River Farg is a small tributary of the River Earn, located in the lieutenancy area of Perth and Kinross, central Scotland. Its source is located in Glen Farg reservoir; it winds round roads and farms, and has been forced in many places to change course due to human interference. It ends in a confluence where it joins the Earn.
The name Farg means "wrathful" in Gaelic, referring to the force of the river when in spate.
The river was polluted with aluminium sulphate killing nearly all the fish in May 2014. Scottish Water was fined £8,000 for the incident.
Coordinates: 56°20′41″N 3°20′41″W / 56.34461°N 3.34465°W