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Geothermal glossary

This glossary explains some of the technical words about geothermal resources used by Waikato Regional Council.

Chloride springs

Geothermal springs can be divided into two types, based on the temperature and composition of the water they produce. Most springs produce warm, weakly mineralised water.

Other springs, known as chloride springs, produce hot or boiling, heavily mineralised alkaline water that is high in chloride and silica. All geysers and springs that produce sinter terraces are chloride springs, for example those at Orakeikorako and Waiotapu.

Chloride springs are rare throughout the Waikato, throughout New Zealand, and throughout the world. They are very vulnerable to damage from the extraction of the geothermal fluid for other uses which divert the chloride water away from the springs.


Ecosystems are communities of living things that interact with each other and their physical environment.

Check out our Regional Policy Statement definition.


Plants and animals that occur naturally only in a specified area or locality.


A fumerole (or fumarole) is a hole from which superheated gas and steam discharge under pressure.

Megawatts (MW)

A watt is a unit of power or how much energy was produced in a certain time (one watt equals one joule per second). A megawatt is 106 watts.


Very small living organisms which can usually only be seen through a microscope (includes bacteria, viruses, fungi and protozoa).

Mineralised fluids

Water and steam containing minerals such as silica, lithium and boron. Also called geothermal water or geothermal fluids.

Check out our Regional Policy Statement definition of geothermal water.

Petajoules (PJ)

A joule is a unit of energy. A petajoule is 1015 joules.


A mineral crust or deposit formed from the minerals (mainly silica) in geothermal water, especially from geysers.

Check out our Waikato Regional Plan definition.