 The Chetwynd River, draining the region north of and , joins the Glenelg east of Burke Bridge.The Glenelg flows generally southwest, to the west of Dergholm State Park towards Dergholm, joined by a number of minor tributaries.From here the river flows south by east, through the town of Casterton, and south of which the Wannon River forms its confluence with the Glenelg.