A river that flows eastwards from Loch Ore for 17 miles (27 km) before joining the River Leven between Milton of Balgonie and Cameron Bridge.
It separates Auchterderran from Cardenden and passes through the southern end of Thornton. The water of the river is rich in iron in its lower course, a problem that was particularly marked during the 1960s and 1970s as a result of minewater discharge from the Westfield Opencast Coal Site into its tributary the Lochty Burn.