One of its tributaries, Darlot Creek, approximately 51 kilometres (32 mi) in length, flows from near Branxholme in a southerly direction through Lake Condah then along the eastern side of the Tyrendarra lava flow before joining the river close to its mouth.[4]
The river was named Clark's River in December 1834 by Edward Henty after the first person in his party to sight it near Tyrendarra. In August 1836 Major Mitchell, who, at the time, was unaware of the presence of the Hentys at Portland Bay named it after FitzRoy Somerset, 1st Baron Raglan when he crossed it near the site of Heywood.[1][5] Darlots (later Darlot) Creek was named after Henry Darlot who rested cattle beside the creek in 1840 and 1841 prior to the establishment of pastoral leases in the area.[6]