Lower Lakes, Coorong and Murray Mouth



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3. ecological objectives and WATER REQUIREMENTS


The six The Living Murray icon sites were selected because of their high conservation, recreation, cultural, heritage and economic value. Based on an understanding of the icon site’s characteristics and ecological requirements, specific First Step Decision interim ecological objectives were developed and approved by the Murray–Darling Basin Ministerial Council in 2003. The aim of the First Step Decision objectives is to maintain the healthy aspects of the icon sites and to begin to address the apparent declines in health of other aspects, as part of a larger contribution to establishing a healthy working river.

3.1 The Living Murray First Step Decision icon site objectives


Since the objectives were approved by Ministerial Council in 2003, jurisdictional agencies have continued to review and refine the First Step interim objectives to develop refined ecological objectives for icon sites. These refined ecological objectives reflect eight years of learnings from the delivery of environmental water, monitoring, modelling and consultation activities and scientific research, and enable a clearer, more effective, evaluation of environmental responses to environmental water delivery. The Lower Lakes, Coorong and Murray Mouth Environmental Water Management Plan includes both the First Step Decision objectives and refined ecological objectives and targets.

The overarching vision of The Living Murray actions in the Lower Lakes, Coorong and Murray Mouth icon site is to facilitate:



A healthier Lower Lakes and Coorong estuarine environment.

The expected outcomes resulting from the successful delivery of the First Step Decision should provide a number of biological and physical benefits, including:



  • an open Murray Mouth (M)

  • more frequent estuarine fish recruitment (F)

  • enhanced migratory wader bird habitat in the Lower Lakes and Coorong (B).

These expected outcomes are recognised as the icon site’s ecological objectives.

3.1.1 Icon Site Ecological Target Review


In order to achieve the objectives of the First Step Decision, ecological and physical targets were developed to specifically quantify changes in the condition of the Lower Lakes, Coorong and Murray Mouth icon site. These targets are based on the site’s requirements to function in a ‘healthy’ ecosystem state, regardless of what is available in environmental water portfolios. Targets are icon site-specific and enable assessment of management actions implemented by The Living Murray program or other environmental water holders.

Ecological targets for the Lower Lakes, Coorong and Murray Mouth icon site have been developed and subsequently revised by a panel of scientific experts, in conjunction with natural resource managers and other key stakeholders e.g. MDBA, CLLMM Scientific Advisory Group (DWLBC 2006; SA MDB NRM Board 2009). Revision has seen targets clarified and has incorporated knowledge gained throughout the ongoing condition monitoring process and consideration of the changing environmental conditions in the icon site.

Each of the revised ecological targets for the Lower Lakes, Coorong and Murray Mouth icon site contributes to at least one environmental objective of the icon site (Table : Summary of revised ecological targets and their contribution to icon site objectives). The relationships between ecological targets and icon site objectives can be either direct and/or indirect.

The purpose of these targets is to enable ongoing assessments of specific bird, fish, vegetation and invertebrate communities of the Lower Lakes, Coorong and Murray Mouth icon site, and the water quality and connectivity conditions which affect the biotic condition, all of which informs the level of achievement of the icon site objectives. Measurable changes to some of the targets can be specifically attributable to management actions of The Living Murray and other environmental water holders, while others may only be inferred.


3.1.2 Other objectives and targets developed for the icon site


The South Australian Department of Environment, Water and Natural Resources long term plan for the Coorong, Lower Lakes and Murray Mouth, “Securing the Future” identifies targets which complement The Living Murray Lower Lakes, Coorong and Murray Mouth Icon Site Environmental Water Management Plan First Step Decision objectives, and provides clear objectives for the future management of the region as a healthy, productive and resilient Wetland of International Importance (DEH 2010b) (Table ). The first six objectives in DEWNR’s long-term plan support Ngarrindjeri cultural life. The open mouth, fish recruitment and bird habitat objectives of TLM also help support Ngarrindjeri cultural life.

The Murray–Darling Basin Plan also complements The Living Murray Lower Lakes, Coorong and Murray Mouth icon site objectives by providing for the integrated management of the Basin water resources in a way that promotes the objectives of the Water Act 2007 (Cth), in particular by providing for:



  • giving effect to relevant international agreements, including the Biodiversity Convention and the Ramsar Convention, to the extent they relate to the use and management of Basin water resources

  • establishment and enforcement of environmentally sustainable limits on the quantities of surface water and groundwater that may be taken from Basin water resources

  • Basin-wide environmental objectives for water-dependent ecosystems, and water quality and salinity objectives

  • use and management of Basin water resources in a way that optimises social, economic and environmental outcomes

  • water to meet its most productive use through the development of an efficient water trading regime across the Murray–Darling Basin

  • requirements that must be met by water resource plans

  • improved water security for all uses of Basin water resources.

The ecological objectives and environmental water requirements of The Living Murray Lower Lakes, Coorong and Murray Mouth Icon Site EWMP were developed in a separate process to those of the Basin Plan, and for different purposes and time scales. As a result, there are some minor differences between some indicators in these Plans; however they are broadly consistent.

The LLCMM Icon Site EWMP indicators aim to identify the flow targets and other water requirements to ensure the site functions in a ‘healthy’ ecosystem state. They are aspirational in nature. They are also focussed on water required for real-time management of the site. Basin Plan indicators were developed as long term statistics for modelling purposes.


Table : Summary of revised ecological targets and their contribution to icon site objectives

Target ID#

Na.

Icon site objective

Ecological target

Open mouth

Fish recruitment

Bird habitat

B1

Maintain or improve bird populations in the Lower Lakes, Coorong and Murray Mouth

Yes

No

Yes

F1

Maintain or improve recruitment success of diadromous fish in the Lower Lakes and Coorong

Yes

Yes

No

F2

Maintain or improve recruitment success of endangered fish species in the Lower Lakes

No

Yes

No

F3

Provide optimum conditions to improve recruitment success of small-mouthed hardyhead in the South Lagoon

No

Yes

No

F4

Maintain or improve populations of black bream, greenback flounder and mulloway in the Coorong

Yes

Yes

No

I1

Maintain or improve invertebrate populations in mudflats (both exposed and submerged)

Yes

Yes

Yes

I2

Provide freshwater flows that provide food sources for Goolwa cockles

Yes

No

No

M1

Facilitate frequent changes in exposure and submergence of mudflats

Yes

No

Yes

M2

Maintain habitable sediment conditions in mudflats

Yes

No

Yes

V1

Maintain or improve Ruppia megacarpa colonisation and reproduction

No

Yes

Yes

V2

Maintain or improve Ruppia tuberosa colonisation and reproduction

No

Yes

Yes

V3

Maintain or improve aquatic and littoral vegetation in the Lower Lakes

No

Yes

Yes

W1

Establish and maintain variable salinity regime with >30% of area below sea water salinity concentrations in estuary and North Lagoon

No

Yes

Yes

W2

Maintain a permanent Murray Mouth opening through freshwater outflows with adequate tidal variations to improve water quality and maximise connectivity

Yes

Yes

Yes

W3

Maximise fish passage connectivity between the Lower Lakes and Coorong

No

Yes

No

W4

Maximise fish passage connectivity between the Coorong and the sea

Yes

Yes

No

Icon site objectives – Open mouth: an open Murray Mouth; Fish recruitment: more frequent estuarine fish recruitment; Bird habitat: enhanced migratory wader bird habitat in the Lower Lakes. Target ID – B: bird-related target; F: fish-related targets; I: invertebrate-related targets; M: mudflat-related targets; V: vegetation-related targets; W: water-related targets.


Table : Summary of how the South Australian Department of Environment, Water and Natural Resources long term plan for the CLLMM targets compliment The Living Murray LLCMM EWMP icon site objectives

CLLMM long term plan target

LLCMM EWMP icon site objective

N/A.

Open mouth

Fish recruitment

Bird habitat

Lake Alexandrina and Lake Albert remain predominantly freshwater and operate at variable water levels

Yes

No

No

The Murray Mouth is predominantly kept open by end-of-system river flows

Yes

Yes

Yes

There is a return of salinity gradients along the Coorong that are close to historic trends with a corresponding response in species abundance

Yes

Yes

Yes

There is a dynamic estuarine zone

Yes

Yes

Yes

The biological and ecological features that give the CLLMM wetlands their international significance, albeit a changed and changing wetland, are protected

Yes

Yes

Yes

There is a return of amenity for local residents and their communities

Yes

No

Yes

There are adequate flows of suitable quality water to maintain Ngarrindjeri cultural life

Yes

Yes

Yes

Tourism and recreation businesses can utilise the lakes and Coorong; and productive and profitable primary industries continue

No

Yes

Yes

Icon site objectives – Open mouth: an open Murray Mouth; Fish recruitment: more frequent estuarine fish recruitment; Bird habitat: enhanced migratory wader bird habitat in the Lower Lakes.



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