Historic piece of dam spillway discovered

It may be showing all the wear and tear of the past 150 years, but a rotting and muddy piece of wood discovered below Dunedin’s Ross Creek reservoir shows one small part of the city’s historic water infrastructure.

The piece of flume, or spillway, from the oldest large dam still in use in New Zealand was discovered as contractors worked on a refurbishment of the 1867 facility.

The $6.1million in work to provide emergency backup water for Dunedin will improve dam safety through the removal of trees and the strengthening of the reservoir bank. An overflow channel is being upgraded and a pipeline built to pump water out of the reservoir.

Council engineering project manager Janan Nirainjanan said the flume was installed about the same time as the reservoir was built.

It was later replaced with a concrete spillway. Contractors excavated upstream and downstream of the wooden flume, but did not find any more sections. The piece had to be removed because of the work, and the council would seek advice on the next steps to remove and preserve the wood, Mr Nirainjanan said. The wooden section would be securely wrapped and kept on site for inspection by archaeologists from Opus and Heritage New Zealand.The dam has a category 1 heritage listing.david.loughrey@odt.co.nz