The Leatham River is a river of the Marlborough Region of New Zealand's South Island. It is the main tributary of the Branch River, itself a tributary of the Wairau River. The Leatham flows north in a parallel valley to the Branch for most of its length before turning northwest to join with the Branch 6 kilometres (4 mi) from its outflow into the Wairau 40 kilometres (25 mi) south of Richmond, New Zealand.
"Place Name Detail: Leatham River". New Zealand Geographic Placenames Database. Land Information New Zealand. Retrieved 12 July 2009.
Coordinates: 41°40′S 173°11′E / 41.667°S 173.183°E