Lake Heron, wetlands and catchment : reconciliation of conflicting uses

Abstract

The steady increase in the demand for land and water resources within the high country has increased the pressure on the resource base and the opportunity for conflict between existing and would-be resource users. It is acknowledged that to adequately satisfy all the various use demands, there is a need for a planning approach which recognises the qualities and limitations of the land for each possible use, which identifies possibilities for integration of uses and which recognises and accounts for the demands and aspirations of all user interests. This study demonstrates such an approach, using as a case study, the Lake Heron basin which lies between the upper Rakaia and South Ashburton Rivers. It begins with a description of the inherent characteristics of the area, and land classification following the land systems approach of Christian (1957). The trends in land use and tenure in the Lake Heron basin are examined in some detail. The interaction between land uses is also examined, and in particular the potential conflict between pastoral farming and wetland preservation is discussed. Tenure is seen as having a major influence on use and also as a means by which potential on site conflict is suppressed. Extensive pastoralism has been shown to have been unsustainable and a trend to more intensive use of the lower altitude land is recognised. However, it is also seen that this trend raises the likelihood of conflict with wetland preservation through nutrient enrichment of waterways from adjoining intensively grazed land. It is noted that protection of natural values occurring outside formally reserved areas cannot be guaranteed without specific protective mechanisms. Recreational use of the area is seen to be increasing. Although use densities are not high at present, the potential for conflict is likely to increase as demand increases. An evaluation is made of each of the land systems identified in the land classification, for their suitability for each of a range of possible land uses. This allows for the identification of suitable uses as a basis for allocation of land to particular uses. Suitability is seen as a necessary, but not sufficient condition for appropriate use of land. The demands and aspirations of user interests is seen to have an important bearing on the identification of appropriate uses. To identify these demands, the policies, goals and objectives of administrative agencies and the aspirations of user groups are described and clarified. The approach to reconciling incompatable demands is outlined but not described. Instead the study concentrates on an examination of the possibilities for integrating pastoral farming and wetland preservation within a portion of the Lake Heron basin. The resource requirements of each are described and a range of pastoral development options are examined from the perspective of financial viability and the impact on wetland values. It is shown that drainage of wetlands cannot be justified on financial grounds. Irrigation of shallow alluvial fan soils is not financially viable under current conditions although this may not necessarily impinge on wetland values. Development of downlands by topdressing, oversowing and subdivision is shown to be financially viable and is likely to have the least impact on wetland values. It is concluded that although a transition to more intensive use of lower altitude land is necessary and desirable from the runholders perspective, it is also shown that this need not conflict with the interests of wetland preservation.