Its mean discharge is approximately 15 cubic kilometres (3.6 cu mi) per year, but the river flows only in the summer as it is frozen to several metres for the rest of the year.

The Inuit village of Kangirsuk lies near the mouth of the Arnaud River on the north shore of Payne Bay, 13 kilometres (8.1 mi) inland from the western coast of Ungava Bay.

About 22 kilometres (14 mi) upstream from Kangirsuk is the Hammer of Thor archaeological site.

Most of the basin is almost totally barren owing to the harsh climate - the mean temperature is only about 7 °C (45 °F) even at the height of summer and continuous permafrost extends deep from only half a metre below the surface.

The only vegetation is low shrubs at the lower levels, for no trees grow within the Arnaud basin even in the most sheltered sites, and the river freezes for too long[clarification needed] to make hydroelectric development feasible.