Lake Te Anau

Those sections of forest along the Te Anau lake shore, resting on unconsolidated material and within ca. 3m of the maximum natural lake level (204.3m above mean sea level), could be threatened by the predicted water table effects (Mark et al. 1972) of lake manipulation required for hydroelectric development. The floristics and structure of this forest were investigated. Five forest associations have been recognised, apparently related to differences in soil moisture conditions.

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These recommendations are aimed at providing the maximum water use for both Lake Manapouri and Lake Te Anau commensurate with the conservation of those features of their natural shorelines which provide ecological stability and a high aesthetic quality.

Approximately 44 per cent of the forested mainland shoreline of Lake Te Anau appears to be vulnerable to high water tables maintained for unnaturally long periods. Results of 22 traverses across representative sites suggest a delicate ecological balance between natural lake level variation, shoreline relief and vegetation.

At non-rocky sites on the shorelines of Lakes Manapouri and Te Anau floristic composition was recorded for one-foot intervals of elevation above and below lake level. Mean daily levels recorded since 1932 have been analysed to find the longest periods of submergence and emergence experienced at each level. A hypothesis that species distribution is governed by extremes of submergence and emergence is supported by the similar periods recorded at the limits of each species at both lakes.

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Lake Te Anau and Lake Manapouri, the two largest lakes in Fiordland National Park, are connected by the Upper Waiau River (Fig. 1). They have been the centre of a decade-long controversy involving the harnessing of their large hydro-electric potential—primarily to smelt bauxite brought from Weipa in Queensland, Australia to the smelter at Bluff.