Waikato region

Two thirds of the water allocated from the Waikato region is from surface water and the remainder is from groundwater.   The region is largely covered by three main river systems;  the Waikato River is the largest, followed by the Waihou and the Piako.

The Waikato River co-management framework between Waikato River iwi and the Crown requires co-management between iwi and the Waikato Regional Council on all aspects of management of the Waikato River.

A large amount of water is imported, via the Tonagariro Power Scheme, into the Waikato region from the Manawatu region.  Exports of water from the region are much smaller than the imports and include water to Auckland city and Glenbrook steel mill.

Nearly all of the water allocated or used in the Waikato  is returned after use and available for further allocation downstream.  This can include water passed through hydro-power turbines where all the water taken is returned.  The majority of other activities return a large portion of the water taken directly back to the river after it is used.

The total amount of water allocated (including power station diversions) in the Waikato catchment exceeds 2900 m³/s (equivalent to 250 million m³/day). The average discharge of the Waikato River at the mouth in comparison is only 430 m³/s. This means that, on average, each drop of water is used more than seven times before flowing out to sea.

Domestic water supplies for both urban and rural communities are the largest consumptive water-use sector in the region. The largest individual abstraction is Auckland’s Waikato River take at Tuakau (Mercer to Mouth catchment) of up to 1.7 m³/s. This consumptive take is likely to increase in the future to meet any increase in Auckland city’s water demand. The next largest net take is for Hamilton’s water supply of 1.0 m³/s (noting that treated wastewater from the city is returned to the river). Other sizeable domestic takes also occur for Taupo and Cambridge. Auckland also takes water from two northern subcatchments of the river.

Irrigation water is primarily used in the agriculture and horticulture sectors.

There are five main sectors of industrial water use in the Waikato, namely timber and paper processing, quarrying and mining, steel production, food processing and electricity generation.