The Tarago River rises in the Tarago State Forest and flows into the Tarago Reservoir at Neerim, which sits in the upper reaches of the Tarago River and harvests inflow from all upstream tributaries. Downstream of the reservoir, the river flows close to the town of Rokeby before meeting the Bunyip River (of which it is a major tributary) at Longwarry North. From there, the Bunyip River flows through a modified, straightened channel — Bunyip Main Drain — to flow into Western Port. This downstream reach supplies many irrigators in the catchment.
The Tarago River continues to be an important place for Traditional Owners and their Nations. The Registered Aboriginal Parties (RAP) covering small sections of the Tarago catchment are the Bunurong Land Council Aboriginal Corporation and the Gunaikurnai Land and Waters Aboriginal Corporation.