Geoscience Reference
In-Depth Information
Table 29.3
Some policy initiatives relevant to environmental flows in the Lower Murray, 1995-2010.
Authority
Key actions
1995
MDB Ministerial Council
(MDBMC)
Adoption of Cap on diversions, set at 1993-1994 diversion volumes
(Cap later found ineffective with users switching to linked sources,
hence increased diversions)
2002
MDBMC
Commenced dredging at mouth; estimated 6 months' duration but
continuing indefinitely (cost A
$
5.2M yr
-1
)
The Living Murray Program
, target 500 GL yr
−1
by June 2009, to improve
fish passage and flows to designated 'icon sites'
2004
MDBMC
2004
National Water Initiative
(all state governments)
States commit to restore over-allocated systems to sustainable levels of
extraction
2006
Plan for Water Security
(Commonwealth
Government)
Federal government pledged A
10B: A
3.1B buy-back, A
5.8B
$
$
$
infrastructure, A
$
0.5B water forecasting, A
$
0.5BMDBA
2006
Senior Basin Officials Group
Crisis conditions: special accounting rules triggered as storages fall below
critical levels
2007
MDBA
Authority appointed to develop Basin Plan
2008
Water for the Future
(Commonwealth
Government)
New federal government extended water security plan to A
$
12.9B, added
extra A
$
2.9B for necessary governance changes to support reforms (e.g.
water trading; Inter-Governmental Agreement)
2008
MDBA
Sustainable Rivers Audit showed 20 of 23 valleys in MDB in 'poor' or 'very
poor' ecological condition
2009
MDBA
By November 2009, 465 GL water entitlements purchased but little
delivered due to restricted supply
2010
MDBA
Release of Guide to the draft Murray-Darling Basin Plan
discharge (e.g. 3000-4000 GL yr
−
1
), they should
be regarded as averages over, say, a decade. The
most conservative ecological prescriptions suggest
that environmental flows for the Lower Murray
need to be delivered as a managed regime of
flow pulses of different magnitudes, with a peak
target of over-bank flows of 10 weeks' duration
every 3 years (1500 GL per event) (Jensen
et al
.
,
2003). This would require flows of 85 000 ML
d
−
1
reaching the South Australian border, achieved
by manipulating storages to augment a minimum
flow of 60 000 ML d
−
1
. When flows are less than
60 000 ML d
−
1
, environmental allocations could be
used to target key wetlands at lower elevations
via floodplain-creek systems. At sites which are
flooded artificially through river regulation, the
floodplain needs dry phases to promote seasonal
pulses of wetland flora and fauna, but the soils also
need to retain sufficient moisture to support plant
germination and seedling survival (Jensen, 2008).
Evolving policy
There have been important policy initiatives
regarding environmental flows (Table 29.3).
In 1995, the Murray-Darling Basin Ministerial
Council authorized a limit ('Cap') on basin-wide
diversions, set at 1993-1994 levels of water
resource 'development'. This had some effect, but
consumers soon turned to other, linked sources,
such as groundwater and on-farm dams, and net
diversions in the ensuing 10 years rose by about
30% (CSIRO, 2008). Moreover, the Cap offered
no defence against a drying climate, foreshadowed
by the first recorded (temporary) closure of the
Murray Mouth in 1982.
In 2004, state governments signed the
National
Water Initiative
(NWI), designed to restore over-
allocated resources in the Murray-Darling Basin
to ecologically sustainable levels of extraction.
Ecologically sustainable levels of extraction have
subsequently been defined as providing sufficient
