Delta at the head of Lake Benmore where the Tekapo and Ohau Rivers drain into the Lake. Both these rivers are artificially held back with water from Lakes Ohau, Tekapo and Pukaki diverted through the canal system the end of which can be seen entering the Lake at the Ohau 3 Power Station.
The Mackenzie Basin is a great place to visit and figure out the engineering making this all possible...