Waitaki District falls partly within the Otago region and partly within the Canterbury region, with 90% of its population living in the Otago region. ​The district incorporates the Ahuriri, Corriedale and Waihemo wards. The district reaches inland from the Waitaki River mouth, up the Waitaki River Valley, through Ohau to the top of the Ahuriri River Valley. It extends south along the east coast beyond Palmerston to Flag Swamp.