Lake Ellesmere / Te Waihora is a broad, shallow coastal lake or
waituna
A waituna is a freshwater coastal lagoon on a mixed sand and gravel (MSG) beach, formed where a braided river meets a coastline affected by longshore drift. This type of waterbody is neither a true lake, lagoon nor estuary.
This classification di ...
, in the
Canterbury
Canterbury (, ) is a City status in the United Kingdom, cathedral city and UNESCO World Heritage Site, situated in the heart of the City of Canterbury local government district of Kent, England. It lies on the River Stour, Kent, River Stour.
...
region of the
South Island
The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...
of New Zealand. It is directly to the west of
Banks Peninsula
Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately and encompasses two large harbours and many smaller bays and coves. The South Island's largest cit ...
, separated from the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
by the long, narrow, sandy
Kaitorete Spit
Kaitorete Spit is a long finger of land which extends along the coast of Canterbury in the South Island of New Zealand. It runs west from Banks Peninsula for 25 kilometres, and separates the shallow Lake Ellesmere / Te Waihora from the Pacific O ...
, or more correctly Kaitorete Barrier. It lies partially in extreme southeastern
Selwyn District
Selwyn District is a predominantly rural district in central Canterbury, on the east coast of New Zealand's South Island. It is named after the Selwyn River / Waikirikiri, which is in turn named after Bishop George Selwyn, the first Anglican bis ...
and partially in the southwestern extension of the former
Banks Peninsula
Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately and encompasses two large harbours and many smaller bays and coves. The South Island's largest cit ...
District, which now (since 2006) is a ward in the city of
Christchurch
Christchurch ( ; mi, Ōtautahi) is the largest city in the South Island of New Zealand and the seat of the Canterbury Region. Christchurch lies on the South Island's east coast, just north of Banks Peninsula on Pegasus Bay. The Avon River / ...
. The lake holds high historical and cultural significance to the indigenous
Māori
Māori or Maori can refer to:
Relating to the Māori people
* Māori people of New Zealand, or members of that group
* Māori language, the language of the Māori people of New Zealand
* Māori culture
* Cook Islanders, the Māori people of the C ...
population and the traditional Māori name ''Te Waihora'', means ''spreading waters''. It has officially had a dual English/Māori name since at least 1938.
Geography and hydrology
Currently Lake Ellesmere / Te Waihora is a
brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
bar-type waterbody, commonly called a lake or
lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...
. It covers an area of , and is New Zealand's 5th largest lake (by area).
Waituna and river mouth lagoons, or
hapua
A hapua is a river-mouth lagoon on a mixed sand and gravel (MSG) beach, formed at the river-coast interface where a typically braided, although sometimes meandering, river interacts with a coastal environment that is significantly affected by long ...
, form an interlinked chain of habitats or
corridor
Corridor or The Corridor may refer to:
Arts, entertainment, and media
Films
* ''The Corridor'' (1968 film), a 1968 Swedish drama film
* ''The Corridor'' (1995 film), a 1995 Lithuanian drama film
* ''The Corridor'' (2010 film), a 2010 Canadia ...
, which run the length of the east coast of the
South Island
The South Island, also officially named , is the larger of the two major islands of New Zealand in surface area, the other being the smaller but more populous North Island. It is bordered to the north by Cook Strait, to the west by the Tasman ...
, from
Wairau Lagoon and
Lake Grassmere
Lake Grassmere / Kapara Te Hau is a New Zealand waituna-type lagoon in the northeastern South Island, close to Cook Strait. The lake is used for the production of salt.
Geography
Lake Grassmere, south of Blenheim and south of the mouth of ...
in Marlborough, through Lake Ellesmere / Te Waihora and
Coopers Lagoon / Muriwai
Coopers Lagoon / Muriwai is a small coastal waituna-type lagoon in the Canterbury region of New Zealand, located approximately half way between the mouth of the Rakaia River and the outlet of the much larger Lake Ellesmere / Te Waihora. While t ...
in Central Canterbury,
Washdyke
Washdyke is an industrial suburb in the north of Timaru, in south Canterbury, New Zealand. State Highway 1 passes through Washdyke on the way north out of the city. The northern terminus of State Highway 8 is in Washdyke.
Washdyke is home of ...
and
Wainono Lagoon
Wainono Lagoon is a shallow lagoon in the southern Canterbury region of New Zealand's South Island. A number of rivers flow into the lagoon, including the Hook River from the north and the Waihao River from the south. Nearby settlements include ...
s in
South Canterbury
South Canterbury is the area of the Canterbury Region of the South Island of New Zealand bounded by the Rangitata River in the north and the Waitaki River (the border with the Otago Region) to the south. The Pacific Ocean and ridge of the Souther ...
, to
Waituna Lagoon
__NOTOC__
The Waituna Lagoon is on the southern coastline of the South Island of New Zealand. It forms part of the Awarua Wetland, a Ramsar site that was established in 1976. It gives it name to waituna, a type of ephemeral coastal lake.
The la ...
in
Southland Southland may refer to:
Places Canada
* Dunbar–Southlands, Vancouver, British Columbia
New Zealand
* Southland Region, a region of New Zealand
* Southland County, a former New Zealand county
* Southland District, part of the wider Southland Reg ...
.
Catchment
Nearly all of the water entering Lake Ellesmere / Te Waihora is derived from the groundwater system that underlies the gravel-dominated strata of the
Central Canterbury Plains. The groundwater system is fed from two sources of recharge: rainfall incident on the plains and subterranean seepage from the
Rakaia
Rakaia is a town seated close to the southern banks of the Rakaia River on the Canterbury Plains in New Zealand's South Island, approximately 57 km south of Christchurch on State Highway 1 and the Main South Line. Immediately north of the ...
and
Waimakariri River
The Waimakariri River is one of the largest rivers in Canterbury, on the eastern coast of New Zealand's South Island. It flows for in a generally southeastward direction from the Southern Alps across the Canterbury Plains to the Pacific Ocean.
...
s. The exception to this is periods of persistent rainfall, usually during winter when discharge into Lake Ellesmere / Te Waihora is supplemented by surface flow derived from the foothills from the
Rakaia Gorge
The Rakaia Gorge is located on the Rakaia River in inland Canterbury in New Zealand's South Island.
Like its neighbour, the Waimakariri River, the Rakaia runs through wide shingle beds for much of its length, but is forced through a narrow can ...
to
Darfield. This illustrates why Lake Ellesmere / Te Waihora has undergone significant ecological transformation in recent years as land use practices in the catchment area have changed. Little detail is known about water level regimes, internal circulation or sedimentation regimes of such lagoons, however it is known that they are significantly vulnerable to human use of the surrounding land and contributing catchments through changes to their hydrological regimes, as well as their sediment and chemical input loads.
Nature
Southern elephant seal
The southern elephant seal (''Mirounga leonina'') is one of two species of elephant seals. It is the largest member of the clade Pinnipedia and the order Carnivora, as well as the largest extant marine mammal that is not a cetacean. It gets it ...
s have been observed here, spending short periods in the lake.
Basking shark
The basking shark (''Cetorhinus maximus'') is the second-largest living shark and fish, after the whale shark, and one of three plankton-eating shark species, along with the whale shark and megamouth shark. Adults typically reach in length. ...
s have occasionally entered the lake.
History
Although Lake Ellesmere / Te Waihora is less than 5000 years old it has undergone many dramatic changes over that short period of time. The lake is a dynamic feature, it has been up to twice its present depth and area in the past, and it has progressed through various stages as it has developed into the brackish bar-type
lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...
that we see today. In chronological order these stages began with the lake as part of Canterbury plains, which were then flooded, forming a bay, then an estuary and finally a lake / lagoon / waituna.
The original formation of Lake Ellesmere / Te Waihora was primarily a function of formation of Kaitorete Barrier. Kaitorete Barrier is often incorrectly referred to as a spit. However, by definition this is incorrect as a spit is widest at the updrift end and tapers to a narrow tip at the downdrift end, but the Kaitorete Barrier is narrower at the southern (updrift) end and widest at the northern (downdrift) end. Kaitorete is also attached to the land at both ends (although somewhat tenuously in south) and therefore technically classed as a
Barrier beach
Barrier islands are coastal landforms and a type of dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything from a ...
.
The formation of Kaitorete Barrier began at the end of the
Last Glacial Maximum
The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent.
Ice sheets covered much of Northern North America, Northern Eur ...
20,000 years ago valley glaciers advanced in Canterbury and subsequent glacial outwash rivers delivered vast quantities of sand, gravel and silt to the coast. Sea level in Canterbury was 130 meters lower than the present day due to glaciation and the coast was as far as 50 km east of its present-day position, meaning the Canterbury plains were double their present width. Subsequent rapid
sea level rise
Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cry ...
then drowned what is now the continental shelf, causing rapid westward migration of the coast. 10,000 years ago the Canterbury coast was approaching the area presently occupied by Lake Ellesmere / Te Waihora. The coast consisted then, as it does now of the unconsolidated sands and gravels of the fans of major rivers in the area such as the Rakaia and Waimakariri. The
Canterbury Bight
The Canterbury Bight is a large bight on the eastern side of New Zealand's South Island. The bight runs for approximately from the southern end of Banks Peninsula to the settlement of Timaru and faces southeast, exposing it to high-energy storm wa ...
was exposed to powerful southerly waves. The combination of weakly resistant unconsolidated sands and gravels and high energy wave action caused rapid coastal erosion and strong net northward transport of the resulting load of sands and gravels fed to the shore.
This completes the sequence of events leading up to the formation of Lake Ellesmere / Te Waihora; with rapid sea-level rise drowning the seaward edge of plains, rapid erosion of coast to south changing its position and providing, in addition to direct river-borne sediments, a massive supply of sea borne sediments and strong net northwards
longshore drift
Longshore drift from longshore current is a geological process that consists of the transportation of sediments (clay, silt, pebbles, sand, shingle) along a coast parallel to the shoreline, which is dependent on the angle incoming wave direction ...
by waves, moving the sediments towards
Banks Peninsula
Banks Peninsula is a peninsula of volcanic origin on the east coast of the South Island of New Zealand. It has an area of approximately and encompasses two large harbours and many smaller bays and coves. The South Island's largest cit ...
and providing the materials to construct
Kaitorete Barrier, that now encloses the lake.
If left to develop naturally Lake Ellesmere / Te Waihora will once again become a saltwater estuary over the next few centuries.
Cultural significance
Lake Ellesmere / Te Waihora has been a revered ''mahinga kai'' (site of traditional significance for food and other natural resources) for
Māori
Māori or Maori can refer to:
Relating to the Māori people
* Māori people of New Zealand, or members of that group
* Māori language, the language of the Māori people of New Zealand
* Māori culture
* Cook Islanders, the Māori people of the C ...
since ancient times and remains central to the lives of many Māori who now live in the area. Under the
Ngāi Tahu
Ngāi Tahu, or Kāi Tahu, is the principal Māori (tribe) of the South Island. Its (tribal area) is the largest in New Zealand, and extends from the White Bluffs / Te Parinui o Whiti (southeast of Blenheim), Mount Mahanga and Kahurangi Poi ...
Claims Settlement 1998, ownership of the lake bed of Lake Ellesmere / Te Waihora was returned to Te Rūnanga O Ngāi Tahu, who are now able to reassert their ''rangatiratanga'' (ownership) over this significant site through direct control of its management.
The traditional name for the lake was ''Te Kete Ika o Rākaihautū'' meaning "the fish basket of
Rākaihautū
Rākaihautū was the captain of the canoe () and a Polynesian ancestor of various , most famously of Waitaha and other southern groups, though he is also known in the traditions of Taitokerau, and in those of Rarotonga.
In Māori traditions ...
". The food sources of Lake Ellesmere / Te Waihora were once abundant and included ''tuna'' (eels), ''pātiki'' (flounder) and ''aua'' (mullet). Lake Ellesmere / Te Waihora was a famed ''mahinga manu wai māori'' (place for taking waterfowl). However, today the richness of Lake Ellesmere / Te Waihora as a ''mahinga kai'' has been largely lost to farmland. While it remains a ''mahinga kai'', its yields have been significantly reduced due to the periodic drainage of the lake in order to maintain reclaimed land and pasture. In the pre-Pākehā past however, the control of the lake’s level was retained at an optimum water level for the birdlife that lived there and provided ''kai'' (food) for many people. The lake was only drained when its level exceeded the normal maximum. ''Kōrari'' (
flax
Flax, also known as common flax or linseed, is a flowering plant, ''Linum usitatissimum'', in the family Linaceae. It is cultivated as a food and fiber crop in regions of the world with temperate climates. Textiles made from flax are known in ...
stalks) were dragged across the sand to make the initial opening of the water to the sea. Such carefully monitored drainage of the lake took place for several hundred years, consistently maintaining Lake Ellesmere / Te Waihora's abundant supply of ''kai''.
In 2007 an assessment of the cultural health of Lake Ellesmere / Te Waihora was undertaken as a combined effort by Ngai Tahu and the
National Institute of Water and Atmospheric Research
The National Institute of Water and Atmospheric Research or NIWA ( mi, Taihoro Nukurangi), is a Crown Research Institute of New Zealand. Established in 1992, NIWA conducts research across a broad range of disciplines in the environmental scien ...
(NIWA). Preliminary findings showed that the lake, and in particular the lake edge still holds significant ''mahinga kai'' values, despite obvious water quality, modification, pressure and native vegetation issues.
As a result of the study, and in particular the interviews with
Tāngata whenua, a number of unique themes and health indicators for Lake Ellesmere / Te Waihora were identified. Drivers of change were identified as: catchment land use modification and intensification; drainage, management and reclamation of wetlands; decline in quality; and access to ''mahinga kai'' and a decline in inflow and lake water quality and quantity. Major changes over time were identified as: the loss of ''mahinga kai'' habitat; loss of ''matauranga Ngai Tahu'' (the knowledge of the local iwi); domination of the fishery by commercial operators; declining access and use of the lake and ''mahinga kai''; and degradation of ''mauri'' (life force) of the lake and ''
mana
According to Melanesian and Polynesian mythology, ''mana'' is a supernatural force that permeates the universe. Anyone or anything can have ''mana''. They believed it to be a cultivation or possession of energy and power, rather than being a ...
''. For the indigenous population desirable outcomes for the future include regeneration and restoration of native habitat; higher and fluctuating lake levels; an increase in the native bird population; reduced sedimentation and erosion; integrated management action; more Ngai Tahu and community use; ''mahinga kai'' activity rejuvenated; and ''Te Kete Ika o Rakaihautu/The Fish Basket of Rakaihautu'' restored.
Recreation
![Little river railtrail near kaituna lagoon](https://upload.wikimedia.org/wikipedia/commons/1/1e/Little_river_railtrail_near_kaituna_lagoon.jpg)
As well as holding high cultural significance to the indigenous population Lake Ellesmere / Te Waihora is also rated as a nationally significant site for recreation. The lake is currently used for a wide range of water and land based activities. It has been identified as nationally significant for waterfowl hunting, and regionally significant for fishing and cycling on the rail trail.
A wide range of both water and land based activities are currently undertaken in the area including fishing, waterfowl hunting, bird-watching, picnicking, camping, cycling, trail biking, scenic driving and water sports such as kayaking and water-skiing. Many of these activities are reliant on a healthy natural ecosystem, especially fish and wildlife habitat, and a decrease in the number of people participating in trout fishing and other activities has been recorded since 1996.
State of the lake and future management
In a 2010 report on lake water quality Lake Ellesmere / Te Waihora was deemed the second most polluted lake in New Zealand in terms of nutrient content and algal growth. Algal blooms are a regular summer occurrence and toxic algae bloomed in the lake in 2009.
Furthermore, most tributaries to the lake exceed the contact recreation guidelines for faecal coliforms and levels of faecal coliforms in Boggy Creek and Doyleston Drain frequently exceed the stock-drinking water guideline value.
Results for E. coli levels are also poor with 42% of sites associated with the lake failing national recreational guide standards for water quality. No sites achieved the shellfish/food gathering standard or were fit for drinking.
However, there is some debate over the definition of the trophic status of Lake Ellesmere / Te Waihora. Although the lake has high nutrient and phytoplankton values that place it in the category of hypertrophic (extremely enriched) the lake does not exhibit many of the characteristics of such a classification. For example, it does not regularly undergo severe oxygen depletion, nor does it produce unsightly toxic algal blooms or fish kills, unlike other lakes in the area with the same trophic status. Furthermore, it supports abundant fish and bird communities.
![RiparianRejuvenation](https://upload.wikimedia.org/wikipedia/commons/d/dc/RiparianRejuvenation.JPG)
Recently it has been recognised that the combination of abstraction and climate was causing adverse effects on groundwater levels that in turn adversely affected the spring fed stream discharge into Lake Ellesmere / Te Waihora. The dependency of lake on the ground water system in its catchment cannot be reduced, but it is to be hoped that by managing groundwater abstractions during times when the inputs to the aquifer system are low the output system to the lake will be maintained at a level that ensures the protection of Lake Ellesmere / Te Waihora. Being a low land lake Lake Ellesmere / Te Waihora not only receives inputs within the immediate vicinity of the lake but also from the wider catchment across the plains to the foothills. The quality of lake tributaries reflects the intensive land use surrounding them, with elevated nutrients and bacteria found in many sites. This has implications for the scale of management issues. The dependency of Lake Ellesmere / Te Waihora on groundwater sourced input has resulted in local authority
Environment Canterbury
Environment Canterbury, frequently abbreviated to ECan. is the promotional name for the Canterbury Regional Council. It is the regional council for Canterbury, the largest region in the South Island of New Zealand. It is part of New Zealand's s ...
implementing a restorative programme for lowland streams. Riparian protection around the lake margin and tributaries will greatly help reduce some contaminant inputs such as sediment and phosphorus, but catchment wide nutrient and water allocation management will be needed to reduce nitrates and improve freshwater inflows to the lake.
See also
*
Lakes of New Zealand
There are 3,820 lakes in New Zealand that have a surface area larger than one hectare. Many of the lakes in the central North Island are volcanic crater lakes. The majority of the lakes near the Southern Alps / Kā Tiritiri o te Moana were carve ...
References
Further reading
* Originally from ''An Encyclopaedia of New Zealand'', edited by A. H. McLintock, published in 1966.
*
External links
Avenues Magazine– ''Ellesmere Swansong: the end of a lake?''
Public Address– ''The End of Lake Ellesmere''
Waihora Ellesmere Trust– set up to educate people about Lake Ellesmere
Map of Banks Peninsula ward, Christchurch
{{DEFAULTSORT:Ellesmere, Lake
Lagoons of New Zealand
Lakes of Canterbury, New Zealand
Wetlands of Canterbury, New Zealand