Grey River

The river was named by explorer Thomas Brunner in honour of New Zealand politician Sir George Grey. The Maori name for the river system and surrounding area is Māwhera, with Māwheranui being distinguished from the northern branch Little Grey River / Māwheraiti.

Numerous sizable rivers are tributaries of the Grey, and several of them also drain lakes. Notable among these are the Ahaura River and the Arnold River, the latter of which is the outflow of Lake Brunner, the largest lake of the northwest South Island. A variety of economic activities occur in the Grey catchment, including dairy farming, coal mining and alluvial gold mining.

Nutrient levels in the lower Grey River have been slowly increasing over the last 10-20 years, but water quality remains satisfactory, primarily due to the majority of its water coming from bush clad hill country.