The Coolumbooka River is formed by the confluence of the Badgerys Creek and the Horseys Swamp Creek in a swampy area, located approximately 10 kilometres (6.2 mi) east northeast of the village of Cathcart.

The river flows generally west southwest, joined by one minor tributary before reaching its confluence with the Bombala River near the town of Bombala.

The river descends 105 metres (344 ft) over its 26 kilometres (16 mi) course, flowing through the northern boundary of the Coolumbooka Nature Reserve.

[2] The river is impounded by Coolumbooka Weir that provides water supply to the town of Bombala.

This New South Wales river or creek related article is a stub.