From the foothills of the Herveys Range, the Bogan River rises to the west of the headwaters of the Little River at Cooks Myalls, near Goonumbla, 19 kilometres (12 mi) north-west of Parkes. The river flows in a generally north-north-westerly direction past Tottenham, Peak Hill and through Nyngan. East of Bourke, the Bogan River joins with the Little Bogan River to form the Darling River. The Bogan River has over twenty tributaries. The main tributaries to the west are Bullock, Bulbodney, Pangee and Whitbarrow Creeks. The eastern catchment between the Bogan and Macquarie Rivers is ill-defined and has only one major tributary, Mulla Cowal.:11 Other sources have claimed that Bugwah Cowal, and Burrill, Duck and Gunningbar Creeks are important tributaries.
Unlike the other main rivers of inland New South Wales, the Bogan does not rise in the well-watered highland areas, so its flow is low and erratic and not much use for irrigation.
Major weirs along the watercourse are at Muddal Weir, located west of Peak Hill; the Nyngan Weir, located north of Nyngan; and Gongolgon Weir, where the mean daily flow exceeds 700 megalitres (25×106 cu ft).:16