A range of pressures on our inland water environments arise from the drivers identified in Chapter 2 of this report (population and economic growth, and climate change). Impacts from pressures include global changes, such as reduced rainfall as a result of changes in climate and recent droughts; more regional impacts, such as the abstraction of water and changes in flow from water resource development; changes to drainage patterns and pollution from land use; changed land management, including fire regimes and forest practices; damage to riparian areas; and impacts on native ecosystems from invasive animals and plants.
4 Inland water | 3 Pressures affecting inland water environments
At a glance
Much of the pressure on our inland water environment is a legacy of the past—the clearing of native vegetation in catchments, the intentional or accidental introduction of weeds and pests, and the drainage of wetlands. Given the scale and practical irreversibility of this history, these pressures will remain, regardless of the choices we now make about our population growth or resource use.
Extensive land clearing has greatly decreased over the past 30 years (see Chapter 5: Land), but urban expansion continues to affect wetlands and streams on the urban fringe. Progress has been made towards controlling some of the serious weeds affecting inland water environments. The westward spread of cane toads across northern Australia is affecting systems in this region, and introduced fish species continue to have heavy impacts on aquatic ecosystems.
Progress towards restoring some environmental flows, and plans by metropolitan water utilities to reduce future additional demands on freshwater resources are positive changes with respect to the pressures from water abstraction from the natural environment. The breaking of the extended drought in south-eastern Australia has provided much-needed flows. Nevertheless, the long-term environmental health of many southern Australian systems remains compromised by the amount of water abstracted for use. Systems in northern Australia generally have a low level of environmental pressure due to water abstraction.
There is compelling evidence that the ongoing drought, since 1975, in south-west Western Australia is partly related to human-induced climate change.