This unit commences with a description of the distribution, hydrology, chemistry, and ecology of freshwaters with an emphasis on Australia and its water resources. Technologies and their impacts on the freshwater ecosystem are reviewed in detail with a focus on environmental allocations, water use for irrigation and domestic supply, technologies for water re-use and re-cycling, desalination, agricultural effluent re-use and groundwater exploitation, and their likely impacts. Chemical and bio-assessment methods (including river health assessments) for detecting impacts are demonstrated before the unit concludes with a holistic treatment of the trade-offs and management of social, economic, ecological and political issues in water resource management in Australia and overseas.