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Wairau Lagoons

Last Modified: 1-1-2021 8:22

Salt marsh, and channel, Wairau Lagoons
Salt marsh, and channel, Wairau Lagoons
© Christopher Cookson  License this image

The Wairau Lagoons are an extensive estuarine environment covering an area of 1576 hectares located 7.5km south-east of Blenheim at the mouth of the Wairau river. Both ecologically and archeologically they are of national significance. The lagoons formed between 5000-6000 years ago as a spit formed from eroded material washed north by southerly swells enclosing what are now the lagoons. The lagoons are shallow with an average depth of only 0.5 metres.

Human history

Along the boulder bank which separates the lagoons from Cloudy Bay are a series of Māori archaeological sites including middens, campsites and burial grounds (ūrupa). Archaeological evidence suggests that these represent some of the earliest humans to arrive in New Zealand. It is believed that the early Polynesian settlers herded moa from the Wairau plain and surrounding hills along this bank from which there was no possible escape. A number of archaeological remains of extinct water birds are also present including the flightless goose and giant coot. Many of the moa skeletons held in museums around the world come from the boulder bank. Māori dug a number of canals connecting to the lagoons. 

At the time of European settlement the Wairau lagoons stretched some distance inland and contained a large body of fresh water wetlands to the west of the present lagoons. This has since been drained and is now used for farming, however, the treated water from the Blenheim oxidation ponds is discharged through a series of man made wetlands which somewhat compensates for this. During the 1970s, Dominion Salt, operator of the Lake Grassmere solar salt production facilities, proposed using some or all of the lagoons to expand salt production, however a DSIR report1 recommended against any modification of the ecosystem, and the proposed development did not proceed.

Ecology

The saline lagoons attract around 70 species of birds, a number of which breed there. Several new migrants have also been sighted for the first time in New Zealand there. A number of fish species are also common in the warm shallow water, partly the reason for the bird life. Galaxids, bullies, and herrings are common as well as larger fish such as kahawai and baracouta which feed on shrimps and the common mud crab Helica crassa.

Vegetation is typical of South Island salt marshes with a mix of low salt resistant plants, including glasswort Salicornia australis and numerous creeping species. On higher ground stunted plants of saltmarsh ribbonwood and coprosma are present.

Recreation

A walking track from Harding's road provides access to the lagoons, and follows a loop to a shipwreck, the Waverley. This vessel was towed here after its useful working life. It was intended for use as a breakwaker for flood control, however floodwaters carried it to its current resting place where it was used for target practice by the army.

References

Walls, G. Y. (1976). Botanical/ecological notes on the Wairau lagoons, Marlborough. Retrieved January 1, 2021.

Web Links

Cite this page

Wairau Lagoons. (2021) Retrieved May, 8, 2021, from https://www.marlboroughonline.co.nz/marlborough/information/geography/wetlands/wairau-lagoons/

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