The district of Waitaki , in the regions of Canterbury and Otago in New Zealand , stretches the traditional border between the two regions , the Waitaki River . The Waitaki district , in the Canterbury and Otago regions of New Zealand , straddles the traditional border between the two regions , the Waitaki River . The Waitaki River district in the regions of Canterbury and Otago in New Zealand spans the traditional border between the two regions , the Waitaki .