The Hawkesbury-Nepean region: has the optimum population size been exceeded?

Abstract

The Australian Federal Government has not included population size as an intersectoral component of the environmentally sustainable development process. The aim of this article is to show how water quality is a key indicator of environmental degradation and of declines in the quality of life. This study is an analysis of the environmental impacts of population on the Hawkesbury-Nepean River System and of the costs involved in change. Environmental degradation is viewed as the result of population size per capita consumption the quality of technology and the organization of space and technology. The quantity and quality of freshwater systems are considered to be useful indicators of environmental degradation over large spatial areas because the impacts are associated with both land and water environments. The catchment area of this river system covers about 231730 sq. km (68% bushland 5% urban 25% agricultural and 0.1% industrial). About 45% of the land area is protected due to six dams which provide 98% of water used in Sydney Illawarra and the Blue Mountains. Estimated population usage is 600000-700000 people. River flows are modified by dams sewage discharges water abstractions and urban run-off from development. River use includes tourism fishing and recreation. The system suffers from severe eutrophication bacterial contamination toxic pollution and hypoxia. The conclusion was reached after many years of concern that large-scale development should be deferred. However housing plans continue for a 70% population increase by 2008. Sewage treatment improvements are costly. Alternatives are re-use of effluents ($2.5-3.5 billion for nonpotable use and $4-4.5 billion for potable use) diversion to the ocean ($3 billion) zero river discharge ($8400 per property for installation and $700 per annum maintenance) or inland disposal ($19 billion). Environmental protection efforts are also costly: $45 million worth of water for flushing away an algal bloom in 1988. Improvement in the present level of environmental quality is viewed as depending on reduced consumption better technology and improved social organization.