The Resources of Lake Wanaka

Abstract

The purposes of the Lake Wanaka Preservation Act 1973 and the functions of the Guardians appointed by the Minister for the Environment appear to allow a wide or liberal interpretation. While the specific purposes of the Act are to preserve the water levels and shoreline in their natural state and to maintain and improve the quality of the lake water, a function directed to the Guardians is to report and make recommendations on any matter concerning the use of the lake for recreational purposes. With these considerations in mind the Guardians have deemed it important, if not imperative, to arrange for the compilation, publication and distribution of a definitive record of Lake Wanaka in its present natural ecological state, and as a regional locality of development with some problems to be resolved and resources maintained or preserved. In short, the guardians have posed these questions: What does the Wanaka system comprise in terms of natural resources that are implicit in the concept of guardianship? What problems are identified with the resources that may be reported within the purposes of the empowering Act? A report of the Guardians published in 1976, "The issues relating to the level of Lake Wanaka", discussed the significance of the lake and its levels within the context of the Clutha hydroelectricity plans. This critically important controversial topic is not further discussed at this stage. Information of scientific and general interest on Lake Wanaka is possessed by various people, most of whom signified willingness, when approached, to prepare reports on their subject areas of authority or knowledge. Further, it was both timely and fortuitous that the Working Party on Lagarosiphon weed in Lake Wanaka set up by the Officials Committee on Eutrophication had commissioned the Chemistry Division DSIR to provide detailed analyses of the Lake W anaka waters as background information to the inquiry on ingress and spread of this aquatic weed. Through this agency, therefore, the basic information on water quality became available. Until these data were provided, the Guardians would have been unable to plan or think in accord with one of their purposes: "to maintain and as far as possible improve the quality of water in the lake". The water and its chemical properties are reported on in this publication including two practical problems identified with Wanaka water, viz (1) Lagarosiphon: aquatic weed, a potential danger to the efficiency of hydro-electric dams in the Clutha River and (2) the public health problem, Duck or Swimmers' Itch, linked with a host/parasite syndrome. Other subjects the Guardians believe to be basic to an understanding and appreciation of the habitat include the fish and wildlife resources; the physical characteristics and morphology of the lake including bathymetric maps, together with geological features; the climate and meteorology of the region and botany and ecology of the shoreline.