It makes its way down the valley and flows through and looping around the eastern suburbs of Blenheim where it is crossed by the Opawa River Bridge.

It joins the Taylor River in Blenheim (keeping the Ōpaoa name) and flows into Big Lagoon, the estuary it shares with the southern mouth of the Wairau River at Cloudy Bay.

Rangitāne iwi say that the name Ōpaoa literally means smoky river.

With Blenheim built on swampy land, the river was often brown (or 'smoky') as a consequence.

This article about a river in the Marlborough Region is a stub.