By: Christopher Cookson
Castle River is a small tributary of the Awatere River, with its source in mountains to the north of the Awatere Valley the Molesworth area of Marlborough. The Castle river flows east, then south to its confluence with the Awatere River is near Middlehurst Station. The Castle River is crossed by the Awatere Valley Road. Much of the river is braided, however downstream of the Awatere Valley Road bridge to its confluence with the Awatere, it is mostly constrained to a single channel. The bed is shingle, and the riparian zone includes native scrub such as matagouri, grasses, and willows.