Waikato River Source

In July 2002, treated water from the Waikato River entered Greater Auckland’s water supply.

The drought of 1994 and the expanding population meant that an additional, secure and sustainable water source was needed that did not rely on rainfall.

The previous one in 50-year drought security standard was lifted to a one in 200-year standard. This meant an increase from an unrestricted water supply 98 percent of the time to 99.5 percent, which is in line with the practice of major international operations.

At the beginning of the project there were 96 options for the additional water source put forward. These included piping water from Lake Taupo, building new dams in the Hunua Ranges or at Riverhead, extracting water from under Rangitoto Island, treating effluent from the Mangere Wastewater Treatment Plant and desalinating seawater at Westhaven. The various options were assessed against environmental, social, cultural and financial criteria.

In May 1995, all but five had been ruled out because they were too costly, too small or would not meet the needs of the region and the requirements of the Resource Management Act. The short listed options were:

• To take water from the Wairoa River at Trail Road in the Hunua Ranges.
• To construct a new dam at Lower Mangatawhiri in the Hunua Ranges.
• To construct a new dam at Riverhead to store water pumped from two small streams at times when the streams are running at high flow.
• To construct a pipeline from the Waikato River via Paparimu.
• To construct a pipeline from the Waikato River via Papakura.

In selecting the preferred option, Watercare subjected the Waikato proposal to extensive general public consultation. The company also consulted widely with local and national government, iwi, environmental organisations, community groups, schools and property owners. The results of the consultation process was scrutinised during the consent hearings under the Resource Management Act.

The Waikato River was identified as a drought resistant, plentiful, cost-effective source. The environmental impact on the river is minimal because the water is abstracted just before it goes into the Tasman sea and unlike with dam construction, no land is flooded. When there are low river levels, less than one percent of the river's volume will be needed.

The Waikato River water is treated to the highest standards and is safe to drink. The water meets the Ministry of Health New Zealand Drinking Water Standards 2000 and is equal or better to the existing supplies which have an 'A' rating. The plant is the most sophisticated plant in Australasia and uses membrane filter technology.

Up to 75,000 cubic metres of Waikato River water is pumped daily through 38 km of pipes to Auckland, supplying around 10% of the region's needs.