Bill McCormick, Science, Technology, Environment and Resources
Over the years there has been an over-allocation of water
entitlements in many areas of the Murray Darling Basin (MDB). Water
resources have not been able to meet the water needed for
environmental flows and human requirements. To address the problem
the Murray-Darling Basin Ministerial Council introduced a permanent
Cap, starting on 1 July 1997. The Cap is a limit imposed on the
volume of water which could be diverted from the rivers for other
uses such as dams or irrigation.
In 2007 the Commonwealth intervened to address over-allocation
and established the Murray-Darling Basin Authority (MDBA). The MDBA
was to develop and implement a Basin Plan to include Sustainable
Diversion Limits (SDLs). On 1 September 2010 the MDBA
announced that it would be publicly releasing the Guide to the
Proposed Basin Plan on 8 October 2010. Later it will
release the Proposed Basin Plan and the Basin Plan. CSIRO has
advised the MDBA about future climate scenarios for use in modeling
future water yield from catchments for the Basin Plan. A 2008
amendment to the Commonwealth Water Act 2007 provided a
commitment for critical human needs.
The Murray Darling Basin Authority
The MDBA is responsible for planning the integrated management
of the water resources of the MDB. The MDBA will prepare the Basin
Plan for adoption by the Commonwealth Minister for Water and will
implement and enforce the Plan—this will set a new cap on
water use in the Basin. The MDBA also advises the Minister on the
accreditation of state water resource plans (WRP).
The drought from 2001 through 2009 has severely reduced the
water resources of the MDB. The years 2006–07, 2007–08
and 2008–09 had the first, third and seventh lowest inflows
to the Murray River on record. The low flows plus continued water
use, albeit at reduced levels, resulted in the Lower Lakes dropping
to record low levels, exposing acid sulphate soils to the air and
increasing salinity levels six-fold. The drought resulted in a
decrease in both area of irrigation and volume of water used.
The Basin Plan
The Basin Plan, due to begin in 2011, must contain:
- long-term average SDLs for the amount of surface water and
groundwater that can be taken from Basin water resources
- requirements that state WRPs must comply with
- an environmental watering plan for the Basin
- a water quality and salinity management plan for the Basin
- rules about trading of water.
These will operate together to ensure that the social, economic
and environmental outcomes of the water resources are not
compromised. The Plan will also include an outline of risks to
Basin water resources, such as climate change, along with
strategies to manage those risks.
The SDLs will be implemented through the water resource plans,
which will be developed by the states but accredited by the
Commonwealth. However there will be a five-year phase-in period for
the SDLs for each WRP.
The Wentworth Group, in a June 2010 paper, argued that the
MDB should not have its flow regime reduced below two-thirds of its
natural level. To ensure that flow rates stay about this,
reductions in SDLs would be required across the Basin. While the
SDLs could remain at more than 90 per cent of present
diversion levels for most catchments, cuts to diversions in the
Murray and Murrumbidgee rivers would have to be
39 per cent and 65 per cent respectively.
Such potentially large reductions in allocations have been of
great concern for irrigation and farming groups. Early this year
the National Farmers Federation said that, for agriculture, the
Basin Plan was a ‘train smash waiting to happen’.
Reduction in water diversions
In the present WRPs, the reduction in water allocations that are
necessary to meet the new SDLs will be achieved by the Commonwealth
purchasing water entitlements on the water market, and through
improving water use efficiency. Two programs aim to achieve
- the $31 billion Restoring the Balance in the Murray-Darling
Basin program to purchase entitlements for use as environmental
- the $5.8 billion Sustainable Rural Water Use and
The ALP gave a 2010 election commitment that it would buy as
much water as necessary from willing sellers to restore the Murray
River to health as needed under the Basin Plan.
Mining and water
Farmers in parts of the MDB have raised the issue of the impact
of coal mining and coal seam methane extraction on the quantity and
quality of the groundwater resources. Section 255A of the
Water Act 2007 requires independent studies of the impacts
of subsidence mining on the groundwater systems in the Basin before
any mining licences are granted. Concerns remain about the impacts
of coal seam methane production.
Snowy River flows
The Snowy Mountains Scheme diverted water to the MDB and this
reduced the flow of the Snowy River above the Mowamba River to just
one per cent of its normal long-term average. In order to
reduce the environmental impacts on the Snowy from this diversion,
in 2002 NSW, Victoria and the Commonwealth agreed to fund a scheme
to return 21 per cent (212 gigalitres) of the
Snowy’s original flows by 2012. The recent drought has
resulted in a slower release of environmental water than expected.
During the 2010 election campaign the ALP announced that it had
reached an agreement with the NSW and Victorian Governments. This
agreement promised a $13.7 million compensation payment to
Snowy Hydro for the 56 gigalitres in water to be released from
the Jindabyne Dam into the Snowy River over the next two years.
Library publications and key documents
Murray Darling Basin Authority (MDBA),
Issues paper: development of sustainable diversion
limits for the Murray-Darling Basin, MDBA, Canberra, 2009,
A Martyn, J Tomaras and B McCormick, Water
Amendment Bill 2008, Bills digest, no. 45, 2008–09,
Parliamentary Library, Canberra, 2008, http://www.aph.gov.au/library/pubs/bd/2008-09/09bd045.pdf
FHS Chiew, W Cai and IN Smith, Advice on
defining climate scenarios for use in the Murray-Darling Basin Plan
modelling, CSIRO report prepared for the Murray-Darling Basin
Authority, Canberra, 2009,
Wentworth Group of Concerned Scientists (WGCS)
RQ Grafton, I Kowalick, C Miller, T Stubbs,
F Verity and K Walker, Sustainable diversions in the
Murray-Darling Basin: an analysis of the options for achieving a
sustainable diversion limit in the Murray-Darling Basin,
Wentworth Group, Sydney, 2010.