New Zealand is known for its many lakes. It is often photographed and painted. They are used extensively for boating and fishing, but they also provide water for irrigation, drinking, and electricity generation. Every lake is unique and treasured by the people who live near it.
Lake facts and figures
- New Zealand is home to 775 lakes, none of which are more than 0.5 kilometers long. The land area covered by lakes is approximately 1.3%.
- Lake Taupo in central North Island is the largest, covering 623 square kilometers. It is located in a deep basin formed by the massive eruption of Taupo volcano about 26,500 years back.
- All eight of the South Island’s largest lakes are glacial lakes.
- Lake Hauroko in western Southland is the deepest lake at 462 metres. It is the 16th deepest lake on the planet.
- Many lake names begin with the Maori word for lake, ‘roto’. Rotoiti, Rotoroa, Rotomanu (lake with birds), Rotomahana and Rotomanu are just a few examples.
Bathymetry: Studying the depth of lakes
Jack Irwin, a lake scientist, and his colleagues conducted surveys for the New Zealand Oceanographic Institute between 1967 and 1989 to determine the underwater structure and depth of larger lakes. A boat equipped with an echo-sounder, equipment to locate the boat, was used for depth measurements.
The New Zealand Lake Chart Series includes charts that show the contours of depth in approximately 125 lakes.
How lakes form
New Zealand is one of the few countries with lakes of comparable size. It has mountains, glaciers and volcanoes that surround them.
According to their origin, the 775 lakes with a length of half a kilometre and more have been classified.
- 38% of the South Island’s glaciers are responsible for its formation
- 16% for rivers
- 15% from dunes
- 8% artificial
- Landslides: 5%
- 4% from volcanoes (all on the North Island).
- Coast barriers: 4%
- 10% other/unknown.
Lake Tekapo, one of many glacial lakes that have a unique blue-green color, is one of them. This is due to tiny suspended particles (also known as rock flour), which have been removed from the underlying rocks by glaciers.
The glacial periods over the last two millions years covered a lot of the South Island’s higher country. Large, steep-sided valleys were eroded by the glaciers. They often left piles of soil and rocks that served as natural dams. Basins left by the glaciers when they retreated were now filled with lakes, such as Manapouri (Wakatipu), Wanaka, Pukaki and Coleridge. Electricity generation is controlled at the highest levels of many glacial lakes located in the Waitaki and Clutha Rivers.
The Taupo Volcanic Zone, Auckland and surrounding areas are the only places where volcanic lakes can be found. The calderas that fill Lakes Taupo, Rotorua are large volcanic depressions created by the collapse of land after an eruption of ash. Other volcanic lakes can be caused by explosive eruptions that form craters or by lava flows blocking the drainage from rivers.
Natural processes change the drainage, which causes water to pond upwards. This is how river, landslide, landslide, and coastal barrier lakes were formed. A flood can cause a river to change its course and leave behind a portion of the old channel as a lake.
Lake Waikaremoana has been dammed by an old landslide. Te Waihora (Lake Ellesmere), is kept in check by a coastal gravel block that is caused by strong northerly winds.
For power generation and water supply, more than 60 lakes have been man-made. To supply water to Auckland, a number have been created by damming narrow valleys within the Waitakere or Hunua ranges.
Hydroelectric power is generated by the creation of some of the largest artificial lakes. These include the Waikato River chain of artificial lakes and several rivers in the lower South Island. Lake Benmore is New Zealand’s largest artificial Lake, covering a total of 74 kilometres. It can be found on the Waitaki River. Lake Rotorangi is New Zealand’s longest lake, at 46 kms, and can be found near Whanganui on the Patea River.