Lake Ellesmere / Te Waihora is a shallow coastal lagoon or waituna, in the Canterbury region of the South Island of New Zealand. It is directly to the west of Banks Peninsula, separated from the Pacific Ocean by the long, narrow, sandy Kaitorete Spit. It lies partially in extreme southeastern Selwyn District and partially in the city of Christchurch's district. The lake holds high historical and cultural significance to the indigenous Māori 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
Lake Ellesmere / Te Waihora is a brackish bar-type water body, commonly called a lake or lagoon. It covers an area of , and is New Zealand's fifth largest lake.
Nature
alt=Red-Necked Stint (Calidris ruficollis) at mudflat near the southern tip of Kaitorete Spit. This small wading bird is a regular summer migrant to New Zealand, and can regularly be seen on Lake Ellesmere's mudflats.|left|thumb|Red-Necked Stint (Calidris ruficollis) at mudflat near the southern tip of Kaitorete Spit. This small wading bird is a regular summer migrant to New Zealand, and can regularly be seen on Lake Ellesmere's mudflats.
Southern elephant seals have been observed here, spending short periods in the lake. Basking sharks have occasionally entered the lake.
alt=Pied Shag / Kāruhiruhi (Phalacrocorax varius) swimming on water's surface at the small settlement of Fishermans Point near the southern end of the lake. Pied Shags are a regularly seen resident on and around the lake.|thumb|Pied Shag / Kāruhiruhi (Phalacrocorax varius) swimming on water's surface at the small settlement of Fishermans Point near the southern end of the lake. Pied Shags are a regularly seen resident on and around the lake.
Lake Ellesmere is also home to a wide variety of birds, with over 200 species (if extinct species are also included) having been recorded at the lake and its direct surroundings. Lake Ellesmere has become a well-known bird watching location for certain rare species, such as the Australasian Bittern, Marsh Crake and Kotuku. Waterfowl are also prominent residents on the lake, with native species including Paradise Shelduck, New Zealand Scaup, Australasian Shoveler and Grey Teal. Long-Toed Stint, Stilt Sandpiper, and Cox's Sandpiper. Australian Terns are also rare visitors to the lake.
History
The lake 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 current brackish bar-type lagoon. 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.
Cultural significance
Lake Ellesmere / Te Waihora has been an important mahinga kai (site of traditional significance for food and other natural resources) for Māori since ancient times and remains central to the lives of many Māori who now live in the area.
The traditional name for the lake was Te Kete Ika o Rākaihautū meaning "the fish basket of Rākaihautū". The food sources of Lake Ellesmere / Te Waihora were once abundant and included tuna (eels), pātiki (flounder) inanga (whitebait), koura (freshwater crayfish) and aua (mullet). The lake was a famed mahinga manu wai māori (place for taking waterfowl), with many species of wetland birds. The lake was surrounded by raupo (Typha orientalis) and harakeke or New Zealand flax (Phormium tenax), and pīngao (Ficinia spiralis) grew on Kaitorete Spit; all three were harvested for weaving, and black mud (paruparu) from the lake was used for dyeing fibres.
The pā Taumutu, or Te Pā o te Ikamutu, was built at the southwestern corner of Te Waihora, close to the outlet to the sea, sited on a tongue of land surrounded by defensive swamplands. The pā was strategically positioned for access to the lake, to Banks Peninsula to the north, the pā at Kaiapoi and Poranui, and for coastal canoes from Te Maru (Timaru) to the south.</blockquote>Today Lake Ellesmere / Te Waihora is periodically lowered by bulldozers to prevent it encroaching on agricultural land. The bulldozers dig a dry channel to the sea over several days, leaving a small dam which is then breached; the lake then lowers over a week or two until the entrance is blocked by waves and storms again.
State of the lake and future management
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 (NIWA). 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.
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.