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Objective 1: Protection and enhancement of the Basin’s shared environmental assets and water resources

Strategy 1.4

Monitor and report on the health of the Basin’s water and natural resources to inform better decision making

Implementation of this strategy involves combined activity associated with the Sustainable Rivers Audit, the statutory River Murray Water Quality Monitoring Program, assessment of floodplain development proposals along the Murray, and the Northern Basin Program.

Sustainable Rivers Audit

First-ever Basin-wide check on river health

What is the condition of the Murray–Darling Basin’s rivers? For the first time, this question has been comprehensively answered for each of the Basin’s 23 river valleys.

In 2007, the SRA completed the first-ever Basin-wide assessment of river health based on three years of data collection. The assessment was the product of groundbreaking collaboration on river health monitoring by the governments of the six Basin jurisdictions (Queensland, New South Wales, the Australian Capital Territory, Victoria, South Australia, and the Australian Government), and an independent group of river ecologists (the Independent Sustainable Rivers Audit Group (ISRAG)).

ISRAG presented the audit results to Ministerial Council in May 2008, and they have been released as SRA Report 1: a report on the ecological health of rivers in the Murray–Darling Basin, 2004–2007. The ecological health assessment is based on three main ‘themes’ or indicators: fish, macroinvertebrates, and hydrology.

A companion summary report, Murray–Darling Basin Rivers: Ecosystem Health Check 2004–2007, provides ‘report cards’ on river ecosystem health for each of the 23 valleys in the Basin. The report cards visually present a graphic ‘at a glance’ summary of the scientific findings, accompanied by text summaries. This report will enable everyone who is interested in sustainable management of the Basin — from the general community to managers, policy-makers and scientists — to become better informed about the ecological health of the Basin’s rivers.

The report concludes that 13 of the Basin’s 23 valleys are in ‘very poor’ health and an additional 7 are in ‘poor’ health, reinforcing the challenge that has been identified nationally to improve the management of the Basin and its water resources. Valleys in the north are generally in better health than those in the south. The ecological impacts are complex and not cumulative from headwaters to the mouth of the Murray. Table 1.7 shows the ecosystem health assessments by valley.

Table 1.7 SRA ecosystem health assessments by valley

Rank	Valley	Ecosystem health	Fish	Macro-invertebrates	Hydrology
1	Paroo	Good	Moderate	Moderate	Good
2	Border Rivers	Moderate	Moderate	Moderate	Moderate to good
2	Condamine	Moderate	Moderate	Poor	Moderate to good
3	Namoi	Poor	Poor	Poor	Good
3	Ovens	Poor	Poor	Poor	Good
3	Warrego	Poor	Poor	Poor	Good
4	Gwydir	Poor	Poor	Poor	Moderate to good
5	Darling	Poor	Poor	Poor	Poor
5	Murray, Lower	Poor	Poor	Poor	Poor
5	Murray, Central	Poor	Poor	Poor	Moderate
6	Murray, Upper	Very poor	Extremely poor	Moderate	Moderate to good
6	Wimmera	Very poor	Poor	Very poor	Poor
7	Avoca	Very poor	Poor	Very poor	Moderate to good
7	Broken	Very poor	Very poor	Poor	Moderate to good
7	Macquarie	Very poor	Very poor	Poor	Moderate to good
8	Campaspe	Very poor	Extremely poor	Poor	Moderate
8	Castlereagh	Very poor	Extremely poor	Poor	Good
8	Kiewa	Very poor	Very poor	Poor	Good
8	Lachlan	Very poor	Extremely poor	Poor	Moderate to good
8	Loddon	Very poor	Extremely poor	Poor	Moderate
8	Mitta Mitta	Very poor	Extremely poor	Poor	Good
9	Goulburn	Very poor	Extremely poor	Poor	Poor
9	Murrumbidgee	Very poor	Extremely poor	Poor	Poor to moderate

Information provided by the SRA on river health will be a key input to MDBC’s Integrated Basin Reporting process as well as to the development of the Basin Plan by the new Murray–Darling Basin Authority. The report brings the dimension of river health/condition to the assessment of water resources and provides critical information that, considered in conjunction with CSIRO Sustainable Yields Project outputs, will assist in making informed decisions on sustainable diversion limits for Basin valleys.

Ministerial Council has approved an additional $5.7 million over the next three years to expand the scope of SRA monitoring to include the new themes of riverine vegetation and physical form, and to cover the floodplain system as well as the river channel (see illustration below). Approval was granted subject to successful completion of a detailed design phase that will assess the feasibility of using remote sensing as well as field sampling.

Water Quality Monitoring Program

Water quality reflects low inflows

Water quality in the Murray River during 2007–08 reflected the low inflows and associated operating strategies. Water from the upper Murray system — Dartmouth and Hume dams — was relied on for much of the summer, supplemented wherever possible by downstream tributary inflows.

When most of the Murray water comes from Hume Dam, turbidity in the river downstream remains low. The falling flow velocities in the Mallee Reach of the Murray below Boundary Bend allow suspended solids to settle and further reduce turbidity, increasing the risk of algal blooms. In a wetter year, higher flows keep the solids in suspension and help suppress algal growth.

Higher flows occurred in the Mallee Reach in early January and early February 2008 as a result of summer rainfall in the northern Victorian tributaries, raising turbidity at Red Cliffs to levels that were more akin to a wet year. Figure 1.6 shows turbidity and flow during 2007–08, compared with turbidity in a much wetter year (1995–96).

Accordingly, at nearby Colignan there were far fewer days of high algal alerts, compared with the previous summer, when the water was less turbid and the flows were lower. A high algal alert is issued when 4 mm3 or more of toxic algae are present in a litre of river water, and contact with or use of the water must be avoided. Flow manipulation is one of the few measures that will suppress algal growth.

Lake Hume Integrated Water Quality Study

The very low storage levels in Lake Hume as a result of the drought provided an opportunity to study the lake under these conditions. MDBC initiated further sampling and research to better define the risks and to identify opportunities to predict and mitigate poor water quality.

The Lake Hume Integrated Water Quality Study revealed how cyanobacteria growth and movement in Lake Hume appear to be driven by a combination of hydrodynamics and temperature. The Murray arm of the reservoir is a ‘hot spot’ for nutrient production, where stratification promotes release of nutrients from the sediments. At low lake levels nutrients are released into the warm surface layer, stimulating cyanobacteria growth. Warm inflows from the Murray River can then push the blooms towards the main basin of the lake. Under certain conditions, lake levels and inflows can be manipulated to minimise cyanobacteria growth.

The study also found that Lake Hume changes the algal community structure in the Murray River. Upstream of the reservoir, green algae dominate; within and downstream of the reservoir, cyanobacteria dominate. Much of the algal biomass found downstream appears to originate from Lake Hume.

Monitoring algal bloom using digital aerial imagery

At the beginning of 2007, the predictions for low Murray River flows into South Australia were a cause for concern. The potential water quality issues from these low flows included elevated cyanobacterial blooms and buildup of cyanobacteria in connected wetlands. SA Water, with support from MDBC, undertook a pilot project to investigate the use of high-definition aerial photography for the early detection of potential water quality issues.

This monitoring has proven to be invaluable. Algal blooms were detected early in the river channel and water treatment was enhanced at the local treatment plant. Blooms in connected wetlands were detected, as well as numerous issues in both the main channel of the Murray and in backwaters and wetlands. The aerial imagery enabled improved management of these issues and has established a benchmark for Murray River floodplain management.

Assessment of floodplain development proposals

Clause 46 of the Murray–Darling Basin Agreement requires the contracting governments to inform the Commission of proposals that may significantly affect the flow, use, control or quality of the Murray River.

More than 120 development applications were referred to the Commission for advice in 2007–2008. Assessments are based on the Ministerial Council’s stated policy of maintaining or improving water quality.

Northern Murray–Darling Basin Program

New strategic plan developed

The Northern Murray–Darling Basin Program adopted a new strategic plan early in 2008 that focuses on the following priorities:

• improving knowledge of the hydrology and ecology of the northern Basin’s rivers and wetlands to support improved management, including more systematic approaches to long-term ecological research and monitoring. This includes consolidating information that the program has already gained in terms of northern Basin distinctiveness, and linkages with other Basin studies and programs.
• using structured approaches to engage with community, industry and governments. This will involve implementing a communications strategy addressing the features of water resources in the northern Basin and engaging with key stakeholders to inform governments of emerging issues.
• providing support for informed policy responses in areas such as water use efficiency, water recovery and reallocation. This will include collaborating with jurisdictions in identifying priorities and options for water recovery and environmental water allocation to the region’s significant wetlands.

Flooding events and first-ever ‘temporary water’ purchase

During the 2007–2008 summer, the northern Basin’s rivers experienced one of the most significant flood events in the past decade, with significant floods in the Paroo and Warrego systems.

The widespread summer rains resulted in the partial filling of the Ramsar-listed Narran Lakes, but high temperatures in February and March resulted in rapid evaporation.

Large numbers of waterbirds had been attracted to the area to breed. This breeding event was one of the largest ever recorded at Narran Lakes, and the largest for colonial waterbirds in the Murray–Darling Basin since 1998.

In April, MDBC purchased 10,423 ML of irrigation water to provide environmental flows to the wetlands at Narran Lakes, maintaining lake water levels to sustain the breeding birds. Over 74,000 breeding pairs were recorded, including straw-necked ibis and royal spoonbills, and an estimated 80,000 chicks were fledged, due in part to the environmental flows.

This is the first time MDBC has purchased environmental water in the northern Basin, and the also the first time the commission has purchased ‘temporary water’1 for environmental purposes.

The successful outcomes from this initiative were due to the collaboration, involvement and support of the Queensland and New South Wales agencies that provided important data on the feasibility of purchase. Once the decision was made to purchase the water, these agencies also provided on-ground support to liaise with landholders along the Narran River and manage the flow event from the farm involved. Overall, these outcomes are a good example of cooperation among multiple jurisdictions.

A planned comprehensive monitoring and evaluation program aims to determine the ecological responses to the watering and to identify future principles and options for delivering environmental water in the northern part of the Basin, including future use of ‘temporary water.’

Understanding the whole ecosystem

Historically, investment in ecological monitoring and research has largely been on a project-by-project basis. This results in fragmented data and information, and limits the opportunity to improve our understanding of how the Basin ecosystem functions as a whole and our ability to adaptively manage the Basin’s rivers and wetlands.

As part of the Research Data and Reporting Program (see Strategy 3.4), a process has been established and approved this year to review, collate, analyse and synthesise ecological data collected by various MDBC programs. This process will develop an improved systems understanding of the ecological responses of river and wetland systems to management interventions. As a result, MDBC will be able to more effectively implement adaptive management and identify opportunities to increase the ecological benefit generated by the available environmental water.

The process will involve collaboration among a number of MDBC initiatives, including The Living Murray (TLM), Native Fish Strategy, Water Quality Program, Sustainable Rivers Audit and River Murray Water. Additionally, it will feed directly into the Integrated Basin Reporting program.

1     Unlike in the southern connected valleys of the MDB, there are no temporary or annual allocations in unregulated rivers of Qld and northern NSW rivers. In the case of the water purchased for the Narran Lakes, ‘temporary’ water refers to water extracted from rivers or through floodplain harvesting under approved event flow management rules. This water is usually diverted to large on-farm storages until applied to crops.

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