The two trees were among five that were removed from an area near the Information Technology Services Building and taken to a local nursery for safe-keeping while the work was being done. Only one of the five trees has survived.
The memorial trees were a kauri, planted in 1976 and dedicated to prominent New Zealand poet and literary figure Charles Brasch; and a mountain beech planted in 2004 for Dr Robin Law of the Geography Department, who joined the university in 1994 and who died in 2003.
ORC Chief Executive Sarah Gardner said in a statement the council had apologised to the university and to friends and associates of Brasch and Dr Law, and ''expressed its sympathy for the actions that led to the death of the memorial trees''.
She said council staff sincerely regretted any distress the loss had caused.
“The Otago Regional Council wishes to acknowledge the significance of both the memorials and the work of Charles Brasch and Dr Robin Law, to whom the trees were dedicated.
“The Flood Protection Scheme is intended to improve the surroundings to the Water of Leith and the University of Otago’s future Memorial Garden is a part of that work.
"It is our hope that by replacing trees of the same size and species, and perhaps repurposing the wood of the former trees into a feature or sculpture, that we can contribute to the University’s goal of creating a contemplative and shady garden that can be enjoyed by all members of staff and students for years to come.”