Cold Gold Clutha Ltd is seeking consents to suction-mine for gold on the Upper Clutha River from the Luggate Bridge to the confluence of the Clutha and Lindis Rivers — about 23km.
The hearing is in front of commissioners Craig Welsh, of Nelson, Rob van Voorthuysen (chairman), of Napier, and Jane Sinclair, of Queenstown. Consents are required from the Otago Regional Council, the Central Otago District Council and the Queenstown Lakes District Council.
The company has consents to dredge between Roxburgh Dam and Tuapeka Mouth, which were re-consented this year until 2035, authorising mining over more than 900ha of riverbed.
The dredge is a self-powered steel pontoon catamaran 23.9m long with a beam of 6.6m. It is a suction-type dredge which uses hydraulically driven high-pressure water pumps to create suction on the river bottom and send river gravel through a 350mm pipe on to the dredge.
Mr van Voorthuysen said there had been late submissions received up until last week and the applicant agreed to accept them.
Cold Gold Ltd director Peter Hall said gold was needed for fine jewellery as well as for low-carbon alternatives to fossil fuels.
Cold Gold Ltd counsel Bridget Irving offered conditions of CODC and QLDC consents to mitigate concerns raised about the operation, including monitoring noise levels and reducing light spill.
It offered a consent condition of restricting the dredge from spending any longer than three months in a single 250m stretch of river and not returning to that site within the lifespan of the consent. Another condition was not having the dredge within 1km of visible residences on Maori Point and River Ridge Rds and associated side roads or within 500m of the Upper Clutha river trail.
Hours of work would be between 7am-8pm and there would be no work on public holidays.
The company also offered to engage an ecologist to conduct a survey within 10 days of starting work to determine if specified birds were nesting in the area.
If they were, work would not be done within 250m of the nesting area and at least six pest traps would be set around the nesting area.
Ecologist Mark Hammer said it was unlikely fish would be around the dredge for various reasons, including the species not being present in the area or it not being their preferred habitat.
Water clarity could be monitored with a turbidity meter upstream and downstream from the outfall of the dredge.
Testing could be done twice a day, he said.
Landscape architect Jessica McKenzie said suction dredge mining was an anticipated activity by both the CODC and QLDC. The bulk of the operational activity would be within the Central Otago district, which permitted commercial dredging operations using vessels up to 6m long with three staff.
The dredge would be confined to a very small portion of the river and would be transient in nature, meaning the natural characteristic of the bulk of the river would remain unchanged, she said.
Planner Darryl Sycamore agreed with Ms McKenzie the effect on the landscape would be minimal.
To comply with the relevant district plan noise limits, the company would carry out noise measurements within two months of starting work, Mr Sycamore said.
The hearing is set to continue until tomorrow.
Bloom predicted from agitating bed
A freshwater scientist believes dredging undisturbed riverbed will likely lead to a bloom in the Clutha River.
Maori Point residents aired their concerns over a suction dredge working in the waterway if consent is granted to Cold Gold Clutha Ltd.
Māori Point Wines and Vineyard owners Marilyn Duxson and John Harris live next to the river reserve next to the Clutha River.
Dr Duxson strongly disagreed that the effect would be "no more than minor" as the applicants submitted.
The "constant thrum of industrial noise" coming from the dredge would have a major effect on their environment, she said.
Many people walked along the river and the ability of extended family and visitors to swim or kayak in the river daily in summer would be endangered by the cables anchoring the dredge if it was working in the Māori Point area, Dr Duxson said.
She was concerned by the "slight nature of the evidence" in the environmental report commissioned by the applicants and had sought advice from freshwater scientist Roger Young of the Cawthron Institute in Nelson, Dr Duxson said.
Dr Young said the river was lake fed and stayed clear even after rainfall.
The sediment disturbed by dredging had been undisturbed for a long period. Disturbing that would affect the ecological and aesthetic values. A bloom was likely downstream of the dredging, he said.
It was surprising that the report prepared for the applicant by E3 Scientific did not include more than 20 years of data gathered by the Otago Regional Council, Dr Young said.
Trout spawning would occur within the dredging operation, he said.
Another Māori Point property owner, Duncan Kenderdine, asked where the dredge would go when it was not working.
He quoted from applicant Peter Hall’s evidence that he "would like to recover 4oz a day over the 200 days a year the dredge would be operating".
That suggested the dredge would be tied up for weeks or months, Mr Kenderdine said.
Noise was also an issue for Mr Kenderdine.
The dredge could be in the area for a long period, he said.
