The
Waikato River is the longest river in New Zealand. In the
North IslandThe North Island is one of the two main islands of New Zealand, separated from the much less populous South Island by Cook Strait. The island is in area, making it the world's 14th-largest island...
, it runs for 425 kilometres from the eastern slopes of
Mount RuapehuMount Ruapehu, or just Ruapehu, is an active stratovolcano at the southern end of the Taupo Volcanic Zone in New Zealand. It is 23 kilometres northeast of Ohakune and 40 kilometres southwest of the southern shore of Lake Taupo, within Tongariro National Park...
, joining the
Tongariro RiverThe Tongariro River is a river in the North Island of New Zealand. It originates in the Central Plateau of the North Island where it is fed by numerous Tributaries that flow off the surrounding hill ranges and mountains such as Mount Ruapehu...
system and emptying into
Lake TaupoLake Taupo is a lake situated in the North Island of New Zealand. With a surface area of , it is the largest lake by surface area in New Zealand, and the second largest freshwater lake by surface area in geopolitical Oceania after Lake Murray ....
, New Zealand's largest lake. It drains Taupo at the lake's northeastern edge, creates the
Huka FallsThe Huka Falls are a set of waterfalls on the Waikato River that drains Lake Taupo in New Zealand.A few hundred metres upstream from the Huka Falls, the Waikato River narrows from roughly 100 metres across into a narrow canyon only 15 metres across...
, and then flows
northwestThe four cardinal directions or cardinal points are the directions of north, east, south, and west, commonly denoted by their initials: N, E, S, W. East and west are at right angles to north and south, with east being in the direction of rotation and west being directly opposite. Intermediate...
, through the
Waikato PlainsThe Waikato Plains are a large area of low-lying land in the northwest of the North Island of New Zealand. They are the floodplains of the Waikato River, the country's longest river....
. It empties into the
Tasman SeaThe Tasman Sea is the large body of water between Australia and New Zealand, approximately across. It extends 2,800 km from north to south. It is a south-western segment of the South Pacific Ocean. The sea was named after the Dutch explorer Abel Janszoon Tasman, the first recorded European...
south of
AucklandThe Auckland metropolitan area , in the North Island of New Zealand, is the largest and most populous urban area in the country with residents, percent of the country's population. Auckland also has the largest Polynesian population of any city in the world...
, at
Port WaikatoPort Waikato is on the south bank of the Waikato River at its outflow into the Tasman Sea, in northern New Zealand. Now a small town with a population of under 300, it was an important port during the New Zealand Land Wars of the 19th century...
. It gives its name to the
WaikatoThe Waikato Region is a local government region of the upper North Island of New Zealand. It covers the Waikato, Hauraki, Coromandel Peninsula, the northern King Country, much of the Taupo District, and parts of Rotorua District...
region that surrounds the Waikato Plains. The present course of the river was largely formed by the large volcanic eruption from the Lake Taupo volcanic complex 1800 years ago. The large outflow of volcanic debris blocked the old channel to the Firth of Thames at Lake Karapiro and forced the river to turn west and then north. The remains of the old river path can be clearly seen at Hinuera where the cliffs mark the ancient river edges.
The river's main tributary is the
Waipa RiverThe Waipa River is in the Waikato region of the North Island of New Zealand. The headwaters are in the Rangitoto Range east of Te Kuiti. It flows north for 115 kilometres, passing through Otorohanga and Pirongia, before flowing into the Waikato River at Ngaruawahia...
, which has its confluence with the Waikato at
NgaruawahiaNgāruawāhia is a town in the Waikato region of the North Island of New Zealand. It is located 20 km north-west of Hamilton at the confluence of the Waikato and Waipa Rivers...
.
The name
Waikato comes from the
Māori languageMāori or te reo Māori , commonly te reo , is the language of the indigenous population of New Zealand, the Māori. It has the status of an official language in New Zealand...
and translates as
flowing water.
The Waikato River has
spiritualSpirituality can refer to an ultimate or an alleged immaterial reality; an inner path enabling a person to discover the essence of his/her being; or the “deepest values and meanings by which people live.” Spiritual practices, including meditation, prayer and contemplation, are intended to develop...
meaning for various local Māori
tribeA tribe, viewed historically or developmentally, consists of a social group existing before the development of, or outside of, states.Many anthropologists use the term tribal society to refer to societies organized largely on the basis of kinship, especially corporate descent groups .Some theorists...
s, including the large
TainuiTainui is a tribal waka confederation of New Zealand Māori iwi. The Tainui confederation comprises four principal related Māori iwi of the central North Island of New Zealand: Hauraki, Ngāti Maniapoto, Ngāti Raukawa and Waikato...
, who regard it as a source of their
manaMana is an indigenous Pacific islander concept of an impersonal force or quality that resides in people, animals, and inanimate objects. The word is a cognate in many Oceanic languages, including Melanesian, Polynesian, and Micronesian....
, or pride. The widely-respected
maraeA marae malae , malae , is a communal or sacred place which serves religious and social purposes in Polynesian societies...
, of
TurangawaewaeTurangawaewae Marae is a very significant marae of the Māori people of New Zealand and is the headquarters for the Māori King Movement...
, is close to its banks at Ngaruawahia.
For many years Tainui tribe have sought to re-establish their links to the river after the
New Zealand land warsThe New Zealand Wars, sometimes called the Land Wars and also once called the Māori Wars, were a series of armed conflicts that took place in New Zealand between 1845 and 1872...
(see Invasion of Waikato) and the subsequent confiscations of the 1860s, and are continuing negotiations with the current New Zealand government.The Tainui Iwi was advised not to bring a case for the river before the Treaty Tribunal as they would not win.An out of court settlement was arranged and the deed of settlement signed by the Crown and Waikato-Tainui in August 2008 settled the Raupatu claim to the Waikato River, although other claims for land blocks and harbours are still outstanding. Waikato-Tainui now have joint management of the river with Environment Waikato.
Course
The river starts as many small streams on the eastern side of Mount Ruapehu. The Mangatoetoenui Glacier (once called the Waikato glacier) is one of the principal sources. The southernmost tributary is called the Upper Waikato Stream. The
Waipakihi RiverThe Waipakihi River is a river of the Waikato Region of New Zealand's North Island. It is the first major tributary of the infant Waikato, flowing southwest from the Kaimanawa Range to reach the Waikato 15 kilometres east of Mount Ngauruhoe on the North Island Volcanic Plateau.-References:...
joins the Waikato from the Kaimanawa Mountains to the west. At the point the river meets the Waihohonu Stream, it becomes called the Tongariro River. The Pouto River joins from
Lake RotoairaLake Rotoaira is a small lake to the south of Lake Taupo on the North Island Volcanic Plateau in New Zealand. It covers an area of 13 km²....
to the east. The Tongariro flows northward, with State Highway 1 in parallel, through the town of
TurangiTurangi is a small town on the west bank of the Tongariro River, 50 kilometres south-west of Taupo on the North Island Volcanic Plateau of New Zealand. It was built to accommodate the workers associated with the Tongariro hydro-electric power development project and their families...
, and into the southern side of Lake Taupo. Extensive engineering of lakes, tunnels and canals are used to generate hydroelectric power in the
Tongariro Power SchemeThe Tongariro Power Scheme is a 360 MW hydroelectricity scheme in the central North Island of New Zealand. The scheme is currently operated by state-owned electricity generation company Genesis Energy....
.
At the northeast point of Lake Taupo is Tapuaeharuru Bay and the town of
TaupoTaupo is a town on the shore of Lake Taupo in the centre of the North Island of New Zealand. It is the seat of the Taupo District Council and lies in the southern Waikato Region....
. The Waikato River leaves the lake and flows northeast past the town, alongside State Highway 1, to the
Huka FallsThe Huka Falls are a set of waterfalls on the Waikato River that drains Lake Taupo in New Zealand.A few hundred metres upstream from the Huka Falls, the Waikato River narrows from roughly 100 metres across into a narrow canyon only 15 metres across...
.
State Highway 5State Highway 5 is the second shortest of New Zealand's eight national highways. It extends from SH 1 at Tirau, on the plains of the Waikato River to SH 2 close to the Hawke Bay coast at Bay View, 10 km north of Napier...
runs more or less parallel to the river as it flows further northeast. About 40 km from the lake, the river flows west and into the southern end of
Lake OhakuriLake Ohakuri, at 12 km², is the largest artificial lake of the Waikato river system in New Zealand. It forms the reservoir for the Ohakuri hydroelectric power station. Construction of the dam, approved in 1955, began in 1956 and was completed in 1960. The lake was filled over 14 days in January and...
. It exits from the northwest end of that lake and flows west through the small Lake Atiamuri and into the long east-west oriented Lake Whakamaru, with
State Highway 30State Highway 30 is a New Zealand State Highway, linking the Waikato and Bay of Plenty towns of Te Kuiti, Mangakino, Rotorua, and Whakatane....
following its course. It passes northwest through
Lake MaraetaiLake Maraetai is one of several artificial lakes formed as part of a hydroelectricity scheme on the Waikato River in the North Island of New Zealand...
and Lake Waipapa, where it is joined by the
Waipapa RiverThe southernmost and largest Waipapa River is a river of the Waikato Region of New Zealand's North Island. It flows generally northeast from its origins to the south of the Pureora Forest Park, passing through the southeast corner of the park to reach Lake Waipapa on the Waikato River 10 kilometres...
, then north through
Lake ArapuniLake Arapuni is one of several artificial lakes formed as part of a hydroelectricity scheme on the Waikato River in the North Island of New Zealand. It is located 65 kilometres southeast of Hamilton, to the north of Mangakino....
and into
Lake KarapiroLake Karapiro is an artificial reservoir lake on the Waikato River in the North Island of New Zealand. The lake, near Cambridge and some south-east of the city of Hamilton, was created in 1947 to store water for the Karapiro Power Station, the last of the eight hydroelectric power stations on the...
. Pokaiwhenua Stream joins the river in Lake Karapiro. Nine hydroelectric power stations at eight dams extract energy from the river between Taupo and Karapiro. All the lakes in this stretch of the river (apart from Lake Taupo) are artificial.
Northwest of Lake Karapiro, the river forms the Waikato Basin, flowing through the towns of
CambridgeCambridge is a town in the Waikato region of the North Island of New Zealand. Situated 24 kilometres southeast of Hamilton, on the banks of the Waikato River, Cambridge is known as "The Town of Trees & Champions".In the 1840s Cambridge had a Maori population but in the 1850's missionaries and...
,
HamiltonHamilton is the centre of New Zealand's fourth largest urban area, and Hamilton City is the country's fourth largest territorial authority. Hamilton is in the Waikato Region of the North Island, approximately south of Auckland...
, and
NgaruawahiaNgāruawāhia is a town in the Waikato region of the North Island of New Zealand. It is located 20 km north-west of Hamilton at the confluence of the Waikato and Waipa Rivers...
. It is joined by its largest tributary, the
Waipa RiverThe Waipa River is in the Waikato region of the North Island of New Zealand. The headwaters are in the Rangitoto Range east of Te Kuiti. It flows north for 115 kilometres, passing through Otorohanga and Pirongia, before flowing into the Waikato River at Ngaruawahia...
, at Ngaruawahia. It then flows north through the Taupiri Gorge to enter the lower Waikato region. Further north is
HuntlyHuntly is a town in the Waikato region of the North Island of New Zealand. It is on State Highway 1, 93 kilometres south of Auckland and 35 kilometres north of Hamilton. It is situated on the North Island Main Trunk Railway and straddles the Waikato River.Huntly was called Rahui Pokeka when...
and then
MeremereMeremere is a small town in the northern Waikato region in the North Island of New Zealand. It is located on the east bank of the Waikato River, 50 kilometres north of Hamilton....
, where the
WhangamarinoThe Whangamarino River is a lowland river of the Waikato Region of New Zealand's North Island, draining the Whangamarino Wetland and associated farmland catchment. The river converges with the Waikato River just north of Meremere...
and
Maramarua-References:...
Rivers join it. From Mercer, where the
Mangatawhiri RiverThe Mangatawhiri River is a river of the Auckland and Waikato Regions of New Zealand's North Island. It flows generally southwest from its sources in the Hunua Hills southeast of Clevedon before flowing through a system of irrigation canals at the northern edge of the Waikato Plains close to the...
joins it, the Waikato flows west and southwest. Just before its mouth at
Port WaikatoPort Waikato is on the south bank of the Waikato River at its outflow into the Tasman Sea, in northern New Zealand. Now a small town with a population of under 300, it was an important port during the New Zealand Land Wars of the 19th century...
, the Araroa River joins from the north.
The mean discharge of the Waikato River is 340 m3 /s, with the highest flows typically occurring in July and August. Specific mean annual floods are low (60-70 L s-1 km-2), and the frequency of events with greater than 3 times the median flow is 0.4 events / year, due to flow regulation and groundwater storage in pumice .
Human usage
As well as being a water and
recreationRecreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasure and are considered to be "fun"...
resource, the river was historically a critical communications and transport link for the communities along it.
TaupoTaupo is a town on the shore of Lake Taupo in the centre of the North Island of New Zealand. It is the seat of the Taupo District Council and lies in the southern Waikato Region....
,
MangakinoMangakino is a small town on the banks of the Waikato River in the North Island of New Zealand. It is located close to the hydroelectric power station at Lake Maraetai, southeast of Hamilton. Its population in 2001 was 1257...
,
CambridgeCambridge is a town in the Waikato region of the North Island of New Zealand. Situated 24 kilometres southeast of Hamilton, on the banks of the Waikato River, Cambridge is known as "The Town of Trees & Champions".In the 1840s Cambridge had a Maori population but in the 1850's missionaries and...
,
HamiltonHamilton is the centre of New Zealand's fourth largest urban area, and Hamilton City is the country's fourth largest territorial authority. Hamilton is in the Waikato Region of the North Island, approximately south of Auckland...
, Horotiu,
NgaruawahiaNgāruawāhia is a town in the Waikato region of the North Island of New Zealand. It is located 20 km north-west of Hamilton at the confluence of the Waikato and Waipa Rivers...
,
HuntlyHuntly is a town in the Waikato region of the North Island of New Zealand. It is on State Highway 1, 93 kilometres south of Auckland and 35 kilometres north of Hamilton. It is situated on the North Island Main Trunk Railway and straddles the Waikato River.Huntly was called Rahui Pokeka when...
,
Hampton DownsHampton Downs Motorsport Park is situated in North Waikato , New Zealand near the Meremere drag strip and the dirt track club. The motorsport park is an ambitious privately funded enterprise and the construction began in February 2007. The completion was planned for late 2008 but a particularly wet...
,
MeremereMeremere is a small town in the northern Waikato region in the North Island of New Zealand. It is located on the east bank of the Waikato River, 50 kilometres north of Hamilton....
,
WaiukuWaiuku is a country town in the Franklin District, in the North Island of New Zealand. It is located at the southern end of the Waiuku River, which is an estuarial arm of the Manukau Harbour...
and Port Waikato are on or close to it.The Waikato River in hamilton is frequently used by rowers ,kayakers and powered pleasure craft.Water skiiers and Jet Skis have zones outside the city limits where they can be used.There are 2 ramps for launching boats-one in Pukete and the other just north of the Traffic (Bridge St )bridge.
The river was of
militaryA military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...
significance in the land wars between
BritishThe British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...
and Māori soldiers around 1863, and significant battles were fought. In support of these wars, New Zealand developed its first "navy", the Waikato Flotilla. A
cemeteryA cemetery is a place in which dead bodies and cremated remains are buried. The term "cemetery" implies that the land is specifically designated as a burying ground. Cemeteries in the Western world are where the final ceremonies of death are observed...
containing the
graveA grave is a location where a dead body is buried. Graves are usually located in special areas set aside for the purpose of burial, such as graveyards or cemeteries....
s of the British military dead can be found at
RangiririRangiriri was a rural New Zealand parliamentary electorate in the Auckland Region from 1978 to 1984.-History:The electorate existed only from 1978 to 1984: it replaced the Franklin electorate in 1978, but the name was changed back to Franklin in 1984....
opposite the
hotelA hotel is an establishment that provides paid lodging on a short-term basis. The provision of basic accommodation, in times past, consisting only of a room with a bed, a cupboard, a small table and a washstand has largely been replaced by rooms with modern facilities, including en-suite bathrooms...
,
shopRetail consists of the sale of physical goods or merchandise from a fixed location, such as a department store, boutique or kiosk, or by mail, in small or individual lots for direct consumption by the purchaser. Retailing may include subordinated services, such as delivery. Purchasers may be...
s and
cafeA café , also spelled cafe, in most countries refers to an establishment which focuses on serving coffee, like an American coffeehouse. In the United States, it may refer to an informal restaurant, offering a range of hot meals and made-to-order sandwiches...
.
A
ferryA ferry is a form of transportation, usually a boat, but sometimes a ship, used to carry primarily passengers, and sometimes vehicles and cargo as well, across a body of water. Most ferries operate on regular, frequent, return services...
service along part of its length was for years conducted by Caesar Roose, several of whose descendants still live beside it.
Electricity generation
The Waikato's first hydro-electric
power stationA power station is an industrial facility for the generation of electric energy....
was the
Horahora Power StationHorahora Power Station was an early hydroelectric power station on the Waikato River in New Zealand. It was the country’s first large-scale power station, completed in 1913. Initially built to service a gold mine, the power station was expanded to supply a significant part of the North Island...
, now located under the
Horahora bridge deep beneath the surface of
Lake KarapiroLake Karapiro is an artificial reservoir lake on the Waikato River in the North Island of New Zealand. The lake, near Cambridge and some south-east of the city of Hamilton, was created in 1947 to store water for the Karapiro Power Station, the last of the eight hydroelectric power stations on the...
. Horahora was built to supply
electricityElectricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
for the Martha gold mines at
WaihiWaihi is a town in Hauraki District in the North Island of New Zealand, especially notable for its history as a gold mine town. It had a population of 4,503 at the 2006 census....
.
The river has a series of eight dams and nine hydroelectric power stations that generate electricity for the national grid. These were constructed between 1929 and 1971 to meet growing demand for electricity.
The power scheme begins at Lake Taupo, which has control gates to regulate the flow of water into the river. Once released through the gates it takes over 18 hours for the water to flow to the last power station at Karapiro. On its journey downstream it passes through power stations at Aratiatia, Ohakuri,
AtiamuriAtiamuri Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It is the third of eight hydroelectric power stations on the Waikato River. The station can easily be seen from State Highway 1 between Taupo and Tokoroa.Atiamuri Power Station is ...
,
WhakamaruWhakamaru Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It was the fourth hydroelectric power station on the Waikato River to be installed....
,
MaraetaiMaraetai Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It is the fifth of the eight hydroelectric power stations on the Waikato River, and at 360 MW, is the largest hydroelectric station on the Waikato.The station has two powerhouses -...
,
WaipapaWaipapa is a small township in the Bay of Islands, of Northland New Zealand. It is around 10 minutes drive from Kerikeri,the nearest 'urban' centre to Waipapa, located on State Highway 10. Waipapa itelf is so small, having no supermarket or school, that most people travel into Kerikeri on a daily...
,
ArapuniArapuni Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It is the seventh and penultimate hydroelectric power station on the Waikato River...
and
KarapiroThe Karapiro Power Station is a hydroelectric power station on Waikato River, in the North Island of New Zealand. The power station station lies on Lake Karapiro, upstream from the city of Hamilton...
.
Approximately 4000
gigawatt hoursThe kilowatt hour, or kilowatt-hour, is a unit of energy equal to 1000 watt hours or 3.6 megajoules.For constant power, energy in watt hours is the product of power in watts and time in hours...
(GWh) of electricity is generated annually by the scheme, which is around 13% of New Zealand's total electrical generating capacity.
The river also provides cooling water for the
coalCoal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
/
natural gasNatural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
fired
thermal power stationA thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which drives an electrical generator. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this...
at
HuntlyThe Huntly Power Station is the largest thermal power station in New Zealand and is located in the town of Huntly in the Waikato. It is operated by Genesis Power, a state-owned enterprise, and supplies around 17% of the country's power.-Generation:...
. However, in order to protect aquatic life, conditions are imposed by its resource consent (see
Resource Management ActThe Resource Management Act passed in 1991 in New Zealand is a significant, and at times, controversial Act of Parliament. The RMA promotes the sustainable management of natural and physical resources such as land, air and water...
), specifying the quantity of water that can be removed by the station along with the maximum temperature of the water when returned to the river (25°C). These conditions mean that on very hot summer days the station cannot operate at maximum capacity, sometimes reducing their total output to 40 megawatts (MW). A new
cooling towerCooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water to remove process heat and cool the working fluid to near the wet-bulb air temperature or in the case of closed circuit dry cooling towers rely...
has been built as part of expansion works at the site, which allows one 250 MW unit to run at full load even during such times.
Recreation
The Waikato is renowned among
whitewater kayakingWhitewater kayaking is the sport of paddling a kayak on a moving body of water, typically a whitewater river. Whitewater kayaking can range from simple, carefree gently moving water, to demanding, dangerous whitewater. River rapids are graded like ski runs according to the difficulty, danger or...
enthusiasts, specifically for the Full James rapid located north of Taupo. The Full James was the site of the 1999 World Whitewater Championships, as well as the pre-World event the year before. The lower Waikato is also popular amongst duck shooters.
Lake KarapiroLake Karapiro is an artificial reservoir lake on the Waikato River in the North Island of New Zealand. The lake, near Cambridge and some south-east of the city of Hamilton, was created in 1947 to store water for the Karapiro Power Station, the last of the eight hydroelectric power stations on the...
(an artificial lake) is regarded as one of New Zealand's best
rowingRowing is a sport in which athletes race against each other on rivers, on lakes or on the ocean, depending upon the type of race and the discipline. The boats are propelled by the reaction forces on the oar blades as they are pushed against the water...
venues. The
World Rowing ChampionshipsThe World Rowing Championships is an international rowing regatta organized by FISA . It is a week long event held at the end of the northern hemisphere summer and in non-Olympic years is the highlight of the international rowing calendar.The first event was held in Lucerne, Switzerland in 1962...
in 1978 and
2010The 39th 2010 World Rowing Championships were held at Lake Karapiro, near Cambridge, New Zealand between October 29 – November 7. The annual week-long rowing regatta was organised by FISA . Usually held at the end of the northern hemisphere summer, they were held later in the year in the southern...
, and the
1950 British Empire GamesThe 1950 British Empire Games was the fourth edition of what is now called the Commonwealth Games. It was held in Auckland, New Zealand between the 4th and 11th of February 1950, after a 12-year gap from the 3rd edition of the games...
were hosted at Karapiro.
Boosted by New Zealand Cycle Trail funding, construction is ongoing as of 2009 on completing the
Waikato River TrailsThe Waikato River Trails is a combined walk- and cycleway along the Waikato River. Originally conceived and started by local politicians and trustees, in 2009 the trails became one of the seven Quick Start Projects that form the beginning of the New Zealand Cycle Trail. The trail is proposed to be...
, a 100 km series of connected river cycling trails in the South Waikato.
The Wairere currently operates from
AratiatiaAratiatia Power Station is a hydroelectric power station on the Waikato River, in the North Island of New Zealand. It is the first hydroelectric power station on the Waikato River, and is located downstream of Lake Taupo....
to
OhakuriOhakuri is a dam and hydroelectric power station on the Waikato River, central North Island, New Zealand, midway between Taupo, Rotorua and Hamilton. Its dam is about 5 km upstream of the Atiamuri Dam....
on the Waikato River.
Species
The Waikato River and its hydro lakes are home to at least 19 types of native fish, 10 types of introduced fish. The introduced species include
rainbowThe rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....
and
brown troutThe brown trout and the sea trout are fish of the same species....
providing what has been called "the finest fly-fishing in the world". Other introduced species, like the
carpThe Common carp is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia. The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive...
and
mosquitofishThe mosquitofish is a species of freshwater fish, also commonly, if ambiguously, known by its generic name, gambusia. It is sometimes called the western mosquitofish, to distinguish it from the eastern mosquitofish . It is a member of the family Poeciliidae of order Cyprinodontiformes...
, have become major pests.
Environmental issues
The whole length of the river is administered by the Regional Council, or "Environment Waikato", based in Hamilton. Several major problems currently face the river.
The large
catchmentA drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
area of the Waikato River is highly fertile farmland, so intensive agriculture is present. Due to the agricultural activity within the catchment significant
agricultural pollutionAgricultural pollution comprises wastes, emissions, and discharges arising from farming activities. This includes runoff and leaching of pesticides and fertilizers; pesticide drift and volatilization; erosion and dust from cultivation; and improper disposal of animal manure and carcasses...
is
leachedIn agriculture, leaching refers to the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers, and other factors are taken into account to avoid excessive nutrient loss.Leaching may also refer to ...
into groundwater and contained in the
runoffSurface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
. The mismanagement of nitrogen fertilizer and
effluent spreadingEffluent spreading is a process in which a slurry of effluent from a dairy farm's milking parlor is pumped and spread on pasture. Commonly a rotating sprinkler is used. Dairy manure contains ammonium NH4-N....
practices in
dairy farmingDairy farming is a class of agricultural, or an animal husbandry, enterprise, for long-term production of milk, usually from dairy cows but also from goats and sheep, which may be either processed on-site or transported to a dairy factory for processing and eventual retail sale.Most dairy farms...
is seen as the major causes of this pollution.Since 2000 Environment Waikato has joined with conservation minded farmers to bring about more efficient and scientific use of fertilizers.
The removal of the native vegetation throughout the catchment to accommodate the increasing demand for farmland has also resulted in the
siltSilt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
ing-up of what was once a navigable channel in the river with loose
soilSoil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
s from eroded farmland.
ArsenicArsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
is also a major problem and in places the concentration reaches 0.035 grams of arsenic per cubic metre., greatly exceeding the
WHOWho may refer to:* Who , an English-language pronoun* who , a Unix command* Who?, one of the Five Ws in journalism- Art and entertainment :* Who? , a 1958 novel by Algis Budrys...
provisional guideline of 0.01 grams of arsenic per cubic metre. The majority of arsenic in the Waikato River comes from the
Wairakei Geothermal Power StationThe Wairakei Power Station is a geothermal power station near the Wairakei Geothermal Field in New Zealand. Wairakei lies in the Taupo Volcanic Zone.- History :...
. The amount of arsenic gradually declines, as the river flows northwards and is at its lowest at the Waikato River Heads.
Water at a rate of 75 million litres per day, making 10% of Auckland's needs, is pumped from a point near the seaward end of the river down a 38 km pipe north to
AucklandThe Auckland metropolitan area , in the North Island of New Zealand, is the largest and most populous urban area in the country with residents, percent of the country's population. Auckland also has the largest Polynesian population of any city in the world...
. This is purified in a new treatment plant that meets New Zealand's 2000 drinking water standards according to Water Care NZ. This is equal to or better than the A standard for Auckland's existing water supplies.
Slightly-modified
human wasteHuman waste is a waste type usually used to refer to byproducts of digestion, such as feces and urine. Human waste is most often transported as sewage in waste water through sewerage systems...
s are pumped into the river downriver of several towns. Hamilton city has one of the most modern water treatment systems in the world following a 2003 report by GHB water consultants. In 2007 $22 million was spent upgrading the existing intake station south of the city at Riverlea. This will meet the cities demand until 2016. Waste water in its untreated state is 99.9% water and .1% other matter. A series of sophisticated machines produce clean water of a high standard getting rid of bad tastes odours and toxins to meet the upgraded NZ water standards. The Pukete 2 project which started in 2002 will upgrade the plant in a series of stages costing $24 million. The largest stage -a new bioreactor/clarifier is due for completion in early 2010,according to the services website of the Hamilton City Council.
A further issue is industrial and metropolitan waste from early-established
landfillA landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
s and waste-emitting factories on the banks of the river.
These include an unlined waste dump at Horotiu, just downriver from Hamilton, whose
leachateLeachate is any liquid that, in passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed....
s include
persistent organic pollutantthumb|right|275px|State parties to the Stockholm Convention on Persistent Organic PollutantsPersistent organic pollutants are organic compounds that are resistant to environmental degradation through chemical, biological, and photolytic processes...
s such as
dieldrinDieldrin is a chlorinated hydrocarbon originally produced in 1948 by J. Hyman & Co, Denver, as an insecticide. Dieldrin is closely related to aldrin, which reacts further to form dieldrin. Aldrin is not toxic to insects; it is oxidized in the insect to form dieldrin which is the active compound...
in quantities toxic to
freshwaterFresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
marine life. The 2002 GHD report saw new regulations put in place to make industries comply with a new bylaw which stops hazardous substances entering the water system at all according to the HCC website. Tribes at the northern point of the river who took legal action to oppose the continued operation of this dump spoke of finding many dead, disordered and distressed
fishFish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
near their tribal lands.
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