Is population growth in Waikato and Auckland regions going to put more pressure on water supply?
Auckland needs to quench the thirst of its ballooning population and is looking take more water from the Waikato River.
A leaked resource consent application suggests the supercity's population is expected to outgrow its water supply within the next 35 years.
Watercare, which is owned by the Auckland Council, has applied to take 200,000 cubic metres of water a day - roughly equivalent to 80 Olympic swimming pools - from the Waikato River to meet the region's public demand over the next three decades.
The council organisation already siphons 150,000 cubic metres of water a day from the river but Auckland's population is expected to grow by at least 800,000 people by 2049 - exceeding the city's current supply capabilities.
Ensuring the city's future supply is considered "essential" to the success of Auckland's 30-year growth plan and the Waikato River has been identified as the "preferred" source of water for the region.
But the proposal has alarmed a number of Waikato River users, who fear the plan has the potential to put unsustainable pressure on the resource and, at worst, stunt Waikato's growth.
Waikato Federated Farmers president James Houghton said the application was of "major concern" to farmers.
"There are other options for Auckland but this is the cheapest. Why should Waikato and Waikato industry be penalised because Auckland ratepayers need more water?"
The Hamilton City Council, Waikato District Council and Waipa District Council all take water from the Waikato River to supply homes and businesses.
The river is also used for electricity generation and irrigation.
However, if Watercare's proposed take is approved, the "allocatable flow" of the river would be exceeded, the application said. The "allocatable flow" refers to the percentage of water that can be allocated to users while ensuring the water body is not harmed.
One way of dealing with the over-allocation, the application noted, was for the regional council to "restrict" the take of existing users in the catchment - although that is seen as unnecessary. Waipa District Mayor James Mylchreest said he would be worried if the extraction impacted on other councils in the region.
"Water allocation is becoming a major issue for most councils around the country," he said.
Chris Allen, Hamilton City Council infrastructure general manager, said the council would form a position once it fully understood how the application might affect the river and the council's ability to supply water to Hamilton. Taking water from the Waikato River is one of four options being considered to meet Auckland's future growth.
Watercare is also considering a dam 25 kilometres northwest of Auckland at Riverhead, a new dam across the Mangatawhiri Stream and construction of a desalination plant.
The application said a dam at Campbell Rd (northwest of Auckland) and the Lower Mangatawhiri Dam could be used in combination with the additional Waikato River water but use of the river remained the "preferred future water source" for the Auckland region.
If approved, additional water could be pumped north within a decade, although the exact timing of work would depend on how fast Auckland's population grew. Chris McLay, Waikato Regional Council's resource use group manager, said he could not give an exact timeframe on when the application would be processed, as it was one of many.
Applications were assessed on a first-in, first-served basis. "Decisions on the other applications will need to be made to determine the allocation status for the Watercare application," he said.
The application, which numbers 522 pages, also seeks approval to build new intake and discharge pipes in the riverbed and, once the allocation is confirmed, to expand its water treatment plant near Tuakau.
Part of the proposal also includes an application to discharge water that does not meet the "high standards required for reticulation to users in Auckland" back into the river.
But a quick and easy approval may prove harder to come by than the Auckland Council hopes. Horticulture New Zealand, which represents a number of north Waikato growers with consents to take water from the river, is worried.
Mighty River Power, Fonterra and Waikato-Tainui are also concerned, the report said. Environmental effects included reduced river flow, effects on its water quality and ecology. A change in water level of up to 22 millimetres is predicted.
But all factors have been identified as "minor" or "insignificant". Auckland already receives about 10 per cent of its water supply from the river and has a consent to take 150,000 cubic metres a day until 2032.
- © Fairfax NZ News
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