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 may represent an Old Gaelic adaption of Brittonic *wergā, meaning "anger" (c.f. Welsh gwery).[1]
The river was once a boundary of the Lordship and Barony of Balvaird.
The river was polluted with aluminium sulphate killing nearly all of the fish in May 2014. Scottish Water was fined £8,000 for the incident.[2]