The headwaters are on the eastern flanks of the Southern Alps. The river flows for 70 kilometres (43 mi) through the southernmost part of the Mackenzie Basin before reaching the Ahuriri Arm of Lake Benmore, one of the lakes in the Waitaki hydroelectric project. From there, the waters join with those of the Waitaki, which has its outflow in the Pacific Ocean.
A notable rock formation, the Omarama or Ahuriri River Clay Cliffs, is located close to the river's north bank some 10 kilometres west of the township of Omarama. Omarama is the main settlement close to the river.
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