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Part 1: Protect and enhance the shared water resources and environmental assets of the Basin

Strategy 1.3
Coordinate the implementation of the Basin Salinity Management Strategy

The Basin Salinity Management Strategy (BSMS) 2001–2015 provides a comprehensive approach to addressing one of the most challenging environmental and economic issues facing the Basin. River salinity targets have been established for each tributary valley and for the Basin as a whole measure at Morgan (Morgan target). This approach reflects the shared responsibility for action between the partner governments and the valley communities. It provides a stable and accountable framework for the partners’ joint efforts to manage salinity.

Key elements of the Basin Salinity Management Strategy

Key elements of the Basin Salinity Management Strategy include the setting of salinity targets, the construction of salt interception schemes and a framework to ensure that salinity costs are accounted for and that salinity mitigation offsets are provided if required.

As in the past years, salinity levels in the Murray River, with the exception of the Lower Lakes, continued to be very low during 2006–07. For the 2006–07 year, Murray River salinity at Morgan, South Australia was below 452 EC for 95 per cent of the time compared with the Morgan target of 800 EC. The peak EC recorded at Morgan was only 530 EC.

Salinity levels are influenced by the drought, the operation of the salt interception schemes and improved irrigation practices. In times of drought, there is a decline in rainfall and irrigation infiltration entering the groundwater system. More salt remains in the landscape rather than discharging to tributary rivers and irrigation drains as happens in wetter years. Also, salt accumulates in the lower Murray floodplains such as Chowilla, rather than being regularly flushed to the River by flooding.

Figure 3 shows the salinity levels recorded at Morgan on a daily basis over the past year and the estimated levels that salinity would have reached without salt interception schemes or dilution flows.

Figure 3 The effect of salinity management in the Murray-Darling Basin Daily salinity levels – July 2006 to June 2007

2695 MDBC AR figure 3 effect of salinity.eps

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Table 5 summarises salinity levels recorded at Morgan over four time intervals: one, five, 10 and 25 years. The comparison shows the improvement in salinity levels in the River over almost 30 years. While the recorded salinity is relatively low at present, modelling shows that, under climatic conditions experienced over the Benchmark Period (1975–2000), long-term salinity at Morgan would be less than or equal to 800 EC for 89 per cent of the time, rather than the 95 per cent of the time set as the target by the Strategy.

Table 5 Summary of salinity levels recorded at Morgan
  Time interval Average Median 95 percentile % Time
> 800 EC
1 year July 2006 – June 2007 377 378 452 0%
5 years July 2002 – June 2007 411 386 615 0%
10 years July 1997 – June 2007 477 459 709 0%
25 years July 1982 – June 2007 553 523 937 11%
25 years Recorded 1975–2000 632 608 1,061 23%
25 years Modelled 1988 conditions 1975–2000 665 666 1,058 28%
25 years Modelled 2007 conditions 1975–2000 557 536 876 11%

Implementation of the BSMS

In 2006–07, Ministerial Council and the Commission oversaw the following activities relating to implementation of the BSMS:

  • Progress was made in developing an Irrigation Salinity Accountability Framework in response to the expansion of interstate water trade to the Riverine Plains irrigation region. It is intended that the framework will be completed in 2007–08. It will add to the work already completed in the Mallee region.
  • Progress was also made in developing principles that underpin accounting and assessment frameworks for the salinity and environmental impacts of BSMS and The Living Murray program activities.
  • Improvements were made to the Salinity Registers, including a prototype database for the documentation and decisions underlying each Salinity Register entry.
  • The following reports for 2005–06 were published: the BSMS Annual Implementation Report, its Summary Brochure and the Report of the Independent Audit Group for Salinity.

The Independent Audit Group for Salinity undertook its fourth audit during November 2006. The auditors found that most of the recommendations from their 2004–05 report had been pursued. In particular, they commended:

  • restoration of the rate of implementation of the BSMS, expected to achieve 71 EC credits by 2010
  • positive changes to the Registers requiring significant cooperation and input from the states and the MDBC, and
  • impressive achievements by regional groups in implementing investment plans.

Salinity impact mitigation

Mid-term review

The BSMS requires that a mid-term review be completed by 31 December 2007. The review progressed well throughout 2006–07 and will report on achievements to date and provide an assessment of the implications for salinity management from recent changes in knowledge and policies. The review will also provide an indication of future directions aimed at enabling the BSMS to meet its objectives over the longer term.

Rolling five-year reviews

In addition to the mid-term review, the BSMS requires a five-yearly review of each Salinity Register entry including the impacts of each tributary valley. These reviews may consider the effect of actions on end-of-valley targets and the Basin salinity target (at Morgan, South Australia).

The status of reviews in 2006–07 is as follows:

  • Reviews were completed for the Shepparton Irrigation Region Land and Water Management Plan in Victoria, and the New South Wales Murray Irrigation Land and Water Management Plan.
  • Reviews were undertaken for the Warrego–Paroo catchments; New South Wales’s upland catchments; and the Mallee region. Final reports are expected to be available for these areas early in 2007–08.
  • Reviews started for the Nyah to the Border and Nangiloc–Colignan Salinity Management Plans in Victoria and the Condamine–Balonne in Queensland.

Murray Valley salt interception schemes

In accordance with Schedule C to the Murray-Darling Basin Agreement, and as set out in the Basin Salinity Management Strategy Operational Protocols, a program of joint salt interception schemes is to offset the predicted future increase in the average salinity at Morgan by a total of 61 EC by December 2007. The predicted future increase arises from the impact of past actions and Accountable Actions.

Figure 4 shows the 13 groundwater pumping and drainage disposal schemes in the Murray system.

Figure 4 BSMS achievements
Salt interception schemes remove over 500,000 tonnes of salt annually.

Figure 4

  1. Walkerie groundwater
  2. Woolpunda groundwater
  3. Noora drainage
  4. Bookpurnong groundwater
  5. Rufus River groundwater
  6. Curlwaa groundwater
  7. Lake Hawthorn drainage
  8. Buronga groundwater
  9. Psyche Bend groundwater
  10. Mildura–Merbein groundwater
  11. Mallee Cliffs groundwater
  12. Barr Creek drainage
  13. Pyramid Creek groundwater

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Investigations 2006–07

Sunraysia region

Possibilities for optimising salt interception in the Sunraysia region, on a regional ‘no borders’ approach, continue to be studied.

Considerable effort was focused on understanding the present and future salt disposal requirements for the region. It is intended to present a disposal options paper to the River Murray Water Committee in late 2007.

Salinity monitoring program

Six new salinity measurement pontoons were installed to provide information on the performance of current salt interception schemes within the region and to assist in monitoring further interception opportunities. The project followed a detailed review of surface water salinity monitoring within the region.

Mildura–Merbein

Investigations continued for the Mildura–Merbein Salt Interception Scheme (Victoria). These addressed the potential of full refurbishment of the existing scheme and a possible extension to intercept additional salt loads downstream of the existing works. It is intended that concept designs for the refurbishment will be completed in the next 12 months.

Redcliffs

Investigations have identified potential to develop an interception scheme in the Redcliffs reach to address predominantly pre-1988 salt impacts on the River and floodplain.

Dareton

Investigations have identified interception opportunities in the Dareton Reach of the River.

The focus for 2007–08 will be a proposal to rehabilitate and augment the Mildura–Merbein Salt Interception Scheme, the development of the preferred regional disposal option, and the development of investment proposals for Redcliffs and Dareton areas.

Upper Darling salt interception opportunity (New South Wales)

There is an economic interception opportunity in the Upper Darling that would provide at least a 3.54 EC average benefit at Morgan. In September 2006, Ministerial Council approved the construction of the Upper Darling Salt Interception Scheme subject to the groundwater modelling being independently reviewed and agreed to be ‘fit for purpose’.

Murtho Salt Interception Scheme (South Australia)

There is an interception opportunity in the Murtho area located opposite the town of Renmark and the Chowilla floodplain. Estimates show that about 129 tonnes of salt a day enter the Murray River in this reach, and the amount could rise to 471 tonnes a day by 2015. In December 2006, the MDBC considered a South Australian proposal to construct this scheme. Approval to proceed to a ‘construction ready’ stage was agreed.

Waikerie 2L Salt Interception Scheme (South Australia)

It is feasible to extend the existing Waikerie Salt Interception Scheme from the downstream end of the Waikerie IIA SIS to the downstream boundary of the area serviced by the Qualco–Sunlands Trust Groundwater Control Scheme. Investigations for the proposed Waikerie 2L scheme are complete.

Design and construction of new salt interception schemes, 2006–07

Loxton

At the Loxton Salt Interception Scheme the Thieles and the Caravan Park floodplain borefields are on target to be commissioned by the end of August 2007. Effective interception of the highland component of this scheme is proving to be extremely difficult due to the specific features of the target aquifer.

Pyramid Creek

The borefield and collector pipelines have now been completed at the Pyramid Creek scheme. In addition a deep bore has been drilled close to the salt harvesting operation to provide security of supply to the salt harvester so that the lined ponds can be protected.

Operation and maintenance

Operation and maintenance of the existing MDBC salt interception scheme assets continues to focus on minimising running costs. A particular target was the cost of energy for pumping. By careful monitoring, it has been possible to maintain target groundwater levels while scheduling pumping times to coincide with periods of lower power tariffs. As a consequence significant cost reductions have been achieved.

Table 6 shows the performance of the salt interception schemes over the past year.

Table 6 Joint salt interception scheme performance reporting 2006–07
Salt interception scheme Volume pumped Salt load diverted Average salinity Target achieved Power consumption kWh
(ML) (Tonnes) (EC Units) (% of time)   Totals
Pyramid Creek 1,067 28,475 39,688 100% 140,302
Barr Creek 4,381 30,084 14,339 100% 87,804
Mildura–Merbein 1,432 39,844 47,292 70% 84,214
Mallee Cliffs 1,960 62,550 53,000 70% 661,290
Buronga 2,880 87,930 46,640 98% 597,281
Bookpurnong 1,564 39,569 40,025 50%a 298,901
Woolpunda 5,033 101,800 30,000 98% 3,240,000
Waikerie 3,335 58,300 25,800 95% 1,350,000
Rufus River
Line 1 270 1,364 8,871 77% 20,318
Line 2 207 7,452 54,653 100% 31,772
Line 3 59 2,950 71,982 100% 34,266
Line 4 52 1,820 53,152 100% 30,774
Minor P/S 0 0 200,000 100% 388
Major P/S 494 8,991 29,724 100% 26,180
Sub-total Rufus River 22,577 143,698
Total 22,734 471,129 6,603,490

a. Bookpurnong target achieved was only about 50% due to the extended shutdown to repair the headworks.
Note: This report does not include work under construction at Loxton.

During the year the newly commissioned Bookpurnong Salt Interception Scheme had to be taken out of service due to the failure of a plastic pipe flange that formed part of the pipework at the top of every bore. A new, more robust flange fitting had to be sourced and every flange of that type replaced before the scheme could be put back into service. The faulty flanges had also been incorporated in the Loxton Salt Interception Scheme design, although only a few had been installed. The flanges were replaced and construction of the remainder of the Loxton Scheme will include the replacement type of flange.

Pipeline to the sea

Investigations have been initiated to establish the feasibility of a pipeline delivery system that would efficiently and effectively dispose of saline groundwater from the Riverland Region in South Australia to the sea. The project team is expected to report later in 2007.

Buronga Salt Interception Scheme outfall at Mourquong Basin. Photo: Alison Reid (MDBC)

Buronga Salt Interception Scheme outfall at Mourquong Basin, New South Wales.

(Photo: Alison Reid (MDBC))