Project Shotover, Queenstown's proposed $42 million wastewater treatment plant, could double wastewater rates by 2013 to more than $500 per househould.
Project Shotover strategic project manager Martin O'Malley presented his procurement plan to the Queenstown Lakes District Council at a council meeting on Tuesday. This report shows the predicted operational costs for the first year of operation (2013) as $2.3 million.
The present operational costs for the Shotover ponds is about $375,000 per year.
The council stated if the figure of $2.3 million would stand, it would lead to a wastewater rate of more than $500 per household ($270 in 2009).
Queenstown Mayor Clive Geddes said: "We have flagged in the 10-year plan that it could potentially double wastewater rates for Queenstown from 2013.
These are early projections, and we hope it will be lower than that.
"Once we fully understand the cost to households, then we will need to make that very clear so that our residents can plan for that cost in three to four years' time."
During the meeting, Cr Cath Gilmour said it might take quite an effort to explain the operating costs being six times higher than at present.
The council approved the procurement plan for Project Shotover, deciding on a "design, build and operate" contract to be tendered out to a contractor consortium.
After the meeting, Mr Geddes said the project had now been given "a further green light".