Glossary

anabranch. A branch of a river that leaves the main stream and rejoins it further downstream.

barrages. Five low, wide weirs built at the Murray Mouth to reduce the amount of seawater moving in and out of the Mouth due to tidal movement. They also help control the water level in the Lower Lakes and River Murray below Lock 1.

aquifer. An underground layer of soil, rock or gravel able to hold and transmit water.

baseline conditions. The current status of a system.

Basin Salinity Management Strategy (BSMS). This strategy guides communities and governments in working together to control salinity in the Murray-Darling Basin and their catchments. It establishes targets for the river salinity of each major tributary valley and the Murray-Darling system itself that reflect the shared responsibility for action both between valley communities and states.

biodiversity. The variety of life forms, plants, animals and micro-organisms; the genes they contain; the ecosystems they form; and ecosystem processes.

Cap on water diversions. The limit imposed on the volume of surface water that can be diverted from rivers for consumptive uses. Started in 1995 as the Interim Cap.

catchment.  The area of land drained by a river and its tributaries.

cavitation. Erosion of hydraulic structure surfaces (e.g. steel or concrete) due to the implosion of cavities in a fluid, particularly evident in areas of high flow and marked change of pressures, and characterised by pitting of the surface. It can be structurally damaging if severe and not addressed.

channel capacity. The volume of water that can pass along the river channel at a certain point without spilling over the tops of the banks.

connectivity. Related to maintaining connections between natural habitats, such as a river channel and adjacent wetland areas.

Council of Australian Governments (COAG). The peak intergovernmental forum in Australia, comprising the Prime Minister, state premiers, territory chief ministers and the President of the Australian Local Governments Association.

drawdown targets. A lake level to which it is planned to lower a reservoir or lake as part of an operations cycle, e.g. for environmental or water quality reasons. In some cases there is a targeted rate at which the drawdown occurs, as well as the level target.

dredging. A process whereby machines equipped with scooping or suction devices remove mud etc., in order to deepen a waterway.

easement. A grant of rights over land by a property owner in favour of another person to enter onto land for the purpose of installing and maintaining facilities such as cables, pipelines, etc. An easement may also grant the right to cross over land in order to gain access to other land.

EC (units). Electrical conductivity unit commonly used to indicate the salinity of water (1 EC = 1 microsiemen per centimetre, measured at 25°C).

end-of-valley targets. A water quality target for salinity, set for a point in the lower reach of each catchment.

environmental flows. Any river flow pattern provided with the intention of maintaining or improving river health.

environmental outcome. Project outcomes that benefit the ecological health of the river system.

Environmental Works and Measures Program (EWMP). An eight-year, $150 million program to deliver works and measures to improve the health of the River Murray system by making the best use of the water currently available, optimising the benefits of any water recovered in the future, and considering other policy interventions.

estuary. The part of a river in which water levels are affected by sea tides, and where fresh water and salt water mix.

failure modes effects analysis. A process to determine all the modes by which an asset may fail, the likelihood of that failure and the consequences of failure.

First Step Decision. A decision announced in November 2003 by the Murray-Darling Basin Ministerial Council. The initial focus of the First Step Decision is on maximising environmental benefits for the six significant ecological assets.

fishway. A structure that provides fish with passage past an obstruction in a stream.

flow regime. The spatial and temporal pattern of flows in a river.

fresh. A small rise in river flows, over and above normal flow conditions.

groyne. A protective structure of stone or concrete that extends from the shore into the water to prevent a beach or riverbank from washing away.

hydrology. The study of the distribution and movement of water.

integrated catchment management (ICM). A process through which people can develop a vision, agree on shared values and behaviours, make informal decisions and act together to manage the natural resources of their catchments. Their decisions on the use of land, water and other environmental resources are made by considering the effect of that use on all those resources and on all people within the catchment.

lock. Consists of a rectangular chamber of concrete with gates at each end. It allows vessels to move from one water level to another.

macroinvertebrate. An invertebrate animal (animal without a backbone) large enough to be seen without magnification.

Murray-Darling Basin (MDB). The entire tract of land drained by the Murray and Darling Rivers. The basin covers land in Queensland, New South Wales, the Australian Capital Territory, Victoria and South Australia.

Murray-Darling Basin Commission (MDBC). The executive arm of the Murray-Darling Basin Ministerial Council. MDBC is responsible for managing the River Murray and the Menindee Lakes system of the lower Darling River and advising the Ministerial Council on matters related to the use of water, land and other environmental resources of the Murray-Darling basin.

Murray-Darling Basin Initiative. A partnership of governments and communities formed to enhance the environmental resources of the Murray-Darling Basin.

Murray-Darling Basin Ministerial Council (MDBMC). A council of ministers of contracting governments who hold land, water and environment portfolios. A minister of the Australian Capital Territory also participates under the terms of the memorandum of understanding.

National Action Plan for Salinity and Water Quality (NAPSWQ). A commitment of $1.4 billion over seven years for applying regional solutions to salinity and water quality problems. The aim is for all levels of government, community groups, individual land managers and local businesses to work together in tackling salinity and improving water quality.

National Water Initiative (NWI). In June 2004 the Council of Australian Governments reached agreement on a National Water Initiative to improve the security of water access entitlements, ensure ecosystem health, expand water trading, and encourage water conservation in our cities.

Native Fish Strategy (NFS). This strategy aims to ensure that the Murray-Darling Basin sustains viable fish populations and communities throughout its rivers. The goal of this strategy is to rehabilitate native fish communities to 60 per cent of their estimated pre-European settlement levels within 50 years of implementation.

pile field. A series of closely spaced timber logs driven vertically into stream beds and banks to reduce erosion by dispersing stream energy and diverting flow away from sensitive areas.

rain rejection. The rejection of water (because it has rained while the water is in transit via river or irrigation canal) ordered for irrigation after it leaves the reservoir but before it is taken up by irrigators.

Ramsar-listed wetland. A wetland of international importance as listed in the Ramsar Convention in Iran.

Reference Group. A committee involving a range of expertise to inform and critique projects and project findings.

regulated flow. A controlled flow rate resulting from the influence of a regulating structure, such as a dam or weir.

remotely operated gate. A regulating gate that may be operated from a remote location, such as an office.

renewals annuities. A constant annual amount of funds that over a given time will provide sufficient funds for foreseeable maintenance programs to keep assets at a standard fit for purpose.

riparian. Of, inhabiting, or situated on, the bank and floodplain of a river.

river health. Status of a river system based on water quality, ecology and biodiversity.

River Murray Water (RMW). An internal business unit of the MDBC responsible by specific delegation for exercising the MDBC's function for water and asset management.

salinity. The concentration of dissolved salts in groundwater or river water, usually expressed in EC units or milligrams of dissolved solids per litre.

salinity credits and debits. Accounting units for the Salinity and Drainage Strategy. Credits are obtained through measures that reduce salinity of the River Murray.

salt interception scheme. Involves large-scale groundwater pumping and drainage projects that intercept saline water flows and dispose of them, generally by evaporation.

significant ecological asset (SEA). Six sites that were chosen because they are of regional, national and international importance for their ecological value, and there is concurrence that they are at risk and require improved water flow regimes. These sites are Barmah–Millewa Forest, Gunbower and Koondrook–Perricoota forests, Hattah Lakes, Chowilla Floodplain, Murray Mouth, Coorong and Lower Lakes, and the River Murray Channel.

stoplog. A beam (timber, concrete or steel) inserted into a slotted frame to retain water.

Sustainable Rivers Audit (SRA). A program designed to measure the health of the rivers within the Murray-Darling Basin. The Audit aims to determine the ecological condition and health of river valleys in the Murray-Darling Basin; to give us a better insight into the variability of river health indicators across the Basin over time; and to trigger changes to natural resource management by providing a more comprehensive picture of river health that is currently available.

turbidity. The relative clarity of water, which may be affected by material in suspension in the water.

water market. The buying and selling of water entitlements, on either a temporary or permanent basis, in order to improve the efficiency of water use.

weir. A dam placed across a river or canal to raise or divert the water, or to regulate or measure the flow.

weir pool. The body of water stored behind a weir.

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