The Awatere Freshwater Management Unit (FMU) takes its name from the largest river in the catchment, the Awatere River, and is 1,573 square kilometres in area. The Awatere FMU stretches over 110 kilometres from mountains southeast of Molesworth to the sea between Clifford Bay and Cloudy Bay. To the south are the Inland Kaikoura Mountains with the highest peak being Mt. Tapuae-O-Uenuku (2885m) and to the west and north are several ranges of mountains with peaks between 1600-1800m, including the Black Birch Range. This range separates the Awatere Valley in the south from the Wairau/Waihopai valleys to the north.
Over most of its length, the valley floor is narrow and flanked by intermittent terraces. Inland, the valley floor is largely made up of discontinuous terrace surfaces which, together with low rainfall and severe winters, largely preclude intensive forms of farming. The lower Awatere Valley area is more suited for intensive land use, with a more agreeable climate and more continuous, well-developed terraces.