Concerned Balclutha residents alerted the Otago Daily Times to the gradual growth of gravel islands in the Clutha River recently.
One correspondent, Stephen Hurring, said the banks were reaching a size at which, in the past, they would have been cleared both to mitigate flood risk, and provide construction material. He said the banks were a hazard to rivercraft, and could exacerbate flooding during periods of elevated flow, and questioned why authorities were not managing the increase as he believed they had in the past.
However, the Otago Regional Council said the council did not undertake gravel extraction from the river, although that was likely to form part of future operations as new management plans took shape.
ORC acting consents manager Alexandra King said only one contractor — Andrew Haulage, of Balclutha — held an active consent at present.
"There are rules in our regional water plan about removal of gravel from rivers and other bed-disturbance activities. Some of these activities can be undertaken without consent and others require a resource consent," Ms King said.
Andrew Haulage’s consent, which expires in November 2025, allows it to "disturb the bed of the Koau Branch of the Clutha River/Mata-au for the purpose of extracting up to 5000 cubic metres of gravel per year".
Other contractors holding consents which have expired during the past 30 years — some to extract up to 20,000 cubic metres a year — include Beeby Construction, South Roads, Blackhead Quarries, Fulton Hogan and Mike Hurring Logging.
ORC engineering manager Michelle Mifflin said although the council had not held a consent to extract gravel from the river in the past, this would form part of new regulations.
"Gravel extraction for flood mitigation is being included in the renewal of ORC engineering consents, [which is] in progress with the consent authority. It will be one method to be used where other methods, such as gravel redistribution, have not been successful," Ms Mifflin said.
The council was in the process of developing river management plans for catchments across the province, which were expected to include gravel extraction for flood mitigation, she said.
