A River in Crisis: The Lower River Murray, Australia - River Conservation and Management - page 340

Lakes for 2010-2011 are approaching the long-
term average, compared with record low inflows
in 2002-2009, one year of higher flows has
not been sufficient to repair long-term ecological
damage. The Basin Plan and regional Long-Term
Plan therefore still have critical roles to play in
establishing new water-sharing arrangements to
support ecosystem health, irrigated agriculture and
communities.

needs a minimum 3000-4000 GL annual discharge
for environmental maintenance. Some ecologists
argue that this is insufficient, and figures as high
as 7600 GL yr − 1 have been suggested (Jones
et al . , 2002; MDBA, 2010; Kingsford et al ., 2011).
Increased environmental flows could be sustained
while still providing water to agriculture and Basin
towns, but this will require major reforms and
social adjustment, and the costs as well as the
benefits would need to be shared equitably among
all Australians. Early public reactions to the Guide
to the Basin Plan suggest that concessions to
environmental needs will be limited by concerns
over socio-economic issues.
While targets for environmental flows typically
have

Opportunities

Scientific basis for management
In the last two decades, advances in understanding
water needs for ecological health (Table 29.2) have
led to wide agreement that the Murray Mouth

been expressed as an annual rate of

Table 29.2 Recommendations for environmental flow allocations relevant to the Lower Murray, 1997-2011.

Authors Findings

1997 Jensen and Nicholls, 1997;

Jensen et al . , 1997

Environmental flows to Lower Murray and weir manipulation to increase
flood extent/duration. Preferred Murray water to turbid Darling water.
Managed seasonal variability in mainstream levels

2000 Thoms et al . , 2000 Environmental flows to reinstate key elements of hydrograph, including

small spring floods, seasonal level variations, changed seasonality of
peaks

2000 Jensen et al . , 2000 Environmental flows for Coorong, Lower Lakes and Murray Mouth to

promote fish passage, maintain mudflats for waders and increase tidal
flushing. Maintain salinity in Coorong; keep river mouth open

2001-2002 Whittington et al ., 2001;
Jones et al . , 2002

Concept of 'healthy working river' as compromise between river condition
and human use. Flows required 30% (low probability of recovery), 50%
(medium) and 70% (high), 4000 GL yr −1 needed

2002 Jensen, 2002a, b Wetland wetting and drying cycles managed on 2-yr cycle, max. 18 months

wet, starting spring-summer, max. 6 months dry to limit dry-phase
biomass

2002-2003 Walker, 2002; Nicol et al . ,
2003

Critical indices of water regime are continuity of exposure, rate of
drawdown and depth

2003 Jensen et al . , 2003 Environmental flows to icon sites to complete life cycles of key species, for

initial duration 1 week, 1 in 3 yr (350 GL), interim duration 4 weeks
(700 GL), and long-term duration 10 weeks, 1 in 3 yr (1500 GL)

2008 Wentworth Group of

Concerned Scientists

For moderate-high probability of healthy river system, require additional
1630-3350 GL yr −1 of environmental flows. Total environmental flow
4609-6843 GL yr −1 ,cost $ 8-9 billion

2009 Brookes et al . , 2009 Coorong, Lower Lakes and Murray Mouth require 2000 GL yr −1 through

barrages. Option to pump hypersaline water from South Lagoon as last
resort, to restore hyper-marine conditions

Median annual flow of 3800 GL yr −1 at barrages to sustain ecosystems.
Concern at fragmentation of system

2011 Kingsford et al. , 2011