The Upper Grey River is a river of the West Coast Region of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

's South Island

South Island

The South Island is the larger of the two major islands of New Zealand, the other being the more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman Sea, to the south and east by the Pacific Ocean...

. As the name suggests, it is a stretch of the Grey River

Grey River

The Grey River / Māwheranui is located in the northwest of the South Island of New Zealand. It rises in Lake Christabel, one of numerous small lakes on the western side of the Southern Alps,12 kilometres southwest of the Lewis Pass, and runs westward for 120 kilometres before draining into the...

, and the name is used for the section between the confluence of the Blue Grey River, Brown Grey River, and Crooked Mary Creek in the Southern Alps

Southern Alps

The Southern Alps is a mountain range extending along much of the length of New Zealand's South Island, reaching its greatest elevations near the island's western side...

 and the Upper Grey's confluence with the Little Grey River

Little Grey River

The Little Grey River, also known as the Māwheraiti is a river of the West Coast Region of New Zealand. It is a major tributary of the Grey River / Māwheranui which it joins at Ikamatua....

 25 kilometres southwest of Reefton.