Mythbusting

There are unfortunate misunderstandings and misconceptions surrounding the draft Basin Plan and its implications. The Authority will set the record straight here, as without correction these untruths take on a life of their own.

SDLs do adjust for  annual variability

There have been claims made that the Sustainable Diversion Limits in the proposed Basin Plan do not adjust for annual variability. This is completely wrong. The amount of water able to be taken in a given year under the Basin Plan will vary based on a range of conditions including storage levels etc, using allocation arrangements set out in state water plans and in a similar manner to the current cap arrangements. The important thing is that, on average, the amount taken must not exceed the SDL for a particular catchment - the MDBA will have in place sophisticated accounting arrangements to ensure this does not happen.

We weren't wrong on flood data

The journalist has misunderstood the Authority’s approach to estimating the amounts of water that can be sustainably diverted from the river. It is true that adding the two extra years of inflows will change the long term average of inflows (by 0.13%) but long term average inflows do not simply translate into estimates of SDLs. The information is available on our Mythbusters site – as well as contained in numerous reports on our website – and that information shows that we estimate the SDLs using a model which balances environmental water requirements and socio-economic factors. Therefore the extra two years of inflows do not affect the SDL estimates.

As previously explained and widely reported, we will not be changing the draft plan’s 2009 baseline figures, and changes to historical inflows averages do not mean that the 2,750 GL SDL will be changed by 32 GL (shared across the entire Basin). If people choose to make a formal submission regarding these issues, then those submissions will be considered in the development of the final Basin Plan.

Water will not become salty

The comments by the Wentworth Group are incorrect as they continue to quote from the Goyder Institute's analysis of the preliminary modelling undertaken by the MDBA in 2010. Since that time further substantial analysis and modelling has been done by the MDBA. The work behind the draft Basin Plan draws upon this in-depth analysis.

This modelling indicates that the long-term average salt export target of 2 million tonnes per year will be met with the proposed SDLs in the draft basin Plan. This work involved detailed analysis since 1975, from which point river salinity has been closely modelled, and then extrapolating this information to the 114-year modelled period used for the draft.

The modelling done to inform the draft Basin Plan also indicates that average and peak salinity will be reduced in the lower Murray as a result of the Basin Plan. In relation to drinking and irrigation water quality, salinity concentration is more important than salt load.

The Authority has recently released a report entitled 'Hydrologic modelling to inform the proposed Basin Plan: Methods and results' which sets out the detailed technical analysis of this modelling, including in relation to salt export.

Will adding two years of inflow data make a difference?

The NSW Irrigators' Council and Senator Barnaby Joyce have suggested that the MDBA needs to include the last two years' climate data to determine the sustainable diversion limits ( SDLs) because this will significantly change the estimates. This is not the case.

Estimating SDLs is not a simple averaging and subtraction exercise. The SDLs have been determined using detailed and sophisticated modelling techniques, which are 'the best available hydrologic models for the Murray Darling Basin'.

As the MDBA explained at Senate Estimates on 14 February 2012, we used the historic climate record (the 114 year period between 1895 and 2009 which included the millennium and federation droughts as well as very high flow periods of mid 1950s and 1970s) to model the environmental outcomes of different SDL reduction scenarios (2400 GL, 2750 GL, 2800 GL and 3200 GL) compared with the 'without development' scenario.

It is important that the climate record includes as much natural variability as possible so we can test the performance of each scenario in the very dry, the very wet and all the times in between. But it is the effectiveness of management changes between the various scenarios that is important and how they best meet our desired environmental outcomes, not the climate baseline. If we changed the climate baseline to include 2010 and 2011 data, the relativities between the SDL scenarios would not change. The last two years have been very wet but no wetter than the very wet periods already included in the 114 year period we have used to test the scenarios.

The following graph shows the last 116 years of river flows for the River Murray at Euston and the Darling River at Bourke, and paints a picture of a water supply in Murray–Darling Basin that is highly variable from year to year and highly variable between the Northern and Southern Basin.

Click to enlarge

The MDBA uses models as a way to assess river management options and plans in a highly variable climate. The MDBA has determined that the recovery of a certain volume of water is necessary to achieve the required environmental outcomes in a repeat of the 114 years from 1895 to 2009. The addition of two extra years to the modelling period will not alter the volume of water that needs to be recovered to meet the environmental objectives in the first 114 years of the period.

Recent comments at community meetings have demonstrated a strong belief that the government will force farmers to give up their water.

No-one in the Basin will be forced to give up their water entitlements as a result of the Basin Plan either in the 7 years before the plan is fully implemented or after 2019. If you own a water entitlement, it is up to you whether you sell or keep your water. This guarantee has been given by both the MDBA and Minister Tony Burke, whose department is responsible for water recovery. In addition, the MDBA has strongly recommended that water be recovered as much as possible through infrastructure upgrades rather than buybacks.

The Wentworth Group claims that the 2010 Guide to the Basin Plan is the best publically available science and proposed that between 3,856 GL and 6,983 GL of water needs to be recovered from consumptive use.

The Guide proposed environmental water recovery of 3,000–4,000 GL/y based on a 'rule of thumb' analysis that assumed the environmental water needs would be met by achieving 60–80% of natural flows at the end of each of the major rivers in the Basin. This 'end-of-system' method was not based on the detailed analysis of the 18 key environmental asset indicator sites, as claimed by the Wentworth Group.

On the contrary, the Draft Basin Plan is based on a 'hydrological indicator site' method that uses this detailed environmental analysis of flow needs at sites along the whole length of rivers throughout the Basin (see here).
The end-of-system methodology used in the Guide was not peer reviewed. However, the hydrological indicator site method has been independently reviewed three times throughout its development, the most recent review completed in November 2011 by a scientific panel led by CSIRO. This review confirmed that this science is sufficient to use as a starting point for an adaptive management approach.

The Wentworth Group claims the draft Plan 'does not identify the volume of water required to deliver a healthy working river.'

The draft Basin Plan proposes that surface water use be limited to 10,873 GL/y (long-term average) in order to achieve environmentally sustainable levels of use. The Authority has published a report outlining the methods and modelled outcomes of the process for determining environmentally sustainable levels of surface water use in the draft Plan (also, see our December 7 blog post). The detailed technical reporting on the environmental water requirements of individual sites and the outputs from modelling underpinning this work will be available in February.

The Wentworth Group claims that under the draft Plan most environmental flow targets will not be met and therefore 2,750 GL is not enough.

As identified by CSIRO, the modelled outcomes from the draft Basin Plan proposals see:

many of the achievable flow targets for ecological outcomes are met and for most of the remaining achievable flow targets, there are major improvements relative to current flow conditions. For example, one of the flow targets (16 gigalitres per day for 30 days) for the Gunbower-Koondrook-Pericoota Forest in the Murray, shows an improvement from being met in 32 per cent of years currently, to up to 69 per cent of years under the proposed Basin Plan compared to a target of 70 per cent of years.

The Authority has acknowledged that the higher floodplains in the Lower Murray cannot be inundated with targeted environmental water due to operating rules on river channel capacity, which are in place to prevent flooding of private property.

The Wentworth Group claims the draft Plan cites river management 'infrastructure' as the limiting factor but does not assess the feasibility or cost of redesigning river management infrastructure.

The constraints in the regulated river system are related to major water infrastructure and river operational rules. An example of this is on the Goulburn River, where releases from Lake Eildon are limited to 10,000 megalitre (ML) per day to prevent inundation of private properties.

The Authority has identified opportunities where changes to river management infrastructure, along with river operational rules, physical constraints and environmental works and measures could contribute to more effective and/or efficient use of environmental water. These are outlined in this report.

The Wentworth Group claims the draft Plan does not incorporate in the modelling the impact that increasing groundwater extractions by over 2,600GL will have on surface water flows.

The Wentworth Group claims the draft Plan does not incorporate in the modelling the impact that increasing groundwater extractions by over 2,600GL will have on surface water flows.

In setting the groundwater limits, the Authority has assessed the rates of recharge and the risk of increases in groundwater use to groundwater dependent ecosystems, river flows and the productive base. Currently, up to 2,352 GL/y can be taken from the Basin. In the draft Plan, the Authority is proposing sustainable diversion limits (SDLs) on groundwater use of 4,340 GL/y, which represents about 0.1% of the total groundwater resource (see Delivering a Healthy Working Basin and Catchment by catchment summaries).
The detailed technical reports on the modelling and methods will be available in February.

Read the detailed technical report on the groundwater modelling and methods here.

The Wentworth Group claims the draft Plan sets long term diversion limits on the assumption that there is no risk to river health from climate change.

The draft Plan recognises climate change as a significant risk, but given the uncertainty of climate change impacts in the first 10 years of the first Basin Plan, the proposed SDLs have been developed using the historic climate sequence (1895–2009). This climatic record takes into account extremes of climate, including the recent 'millennium drought' when inflows were 40% below the long-term average. The variability in this climatic sequence is greater than the mid-range climate change impacts projected by CSIRO's Sustainable Yields Project on average water availability for 2030.

The reduction in water use proposed under the draft Basin Plan will provide buffering for the environment from the predicted climate change effects, while further detailed exploration of the implications of climate change continues to be carried out and incorporated in future Plan revisions.

The Basin Plan incorporates current adaptive water allocation processes in place under state water resource plans that take into account seasonal water availability.

The Wentworth Group claims there is no information presented on the effectiveness of the Plan to cope with long dry periods or deliver the volumes of water required keep the Murray mouth open and export the 2,000,000 tonnes of salt each year.

The report The proposed "environmentally sustainable level of take" for surface water of the Murray—Darling Basin: Method and Outcomes details the expected outcomes under drought conditions for key sites, including Hattah Lakes, Chowilla Floodplain and the Coorong, Lower Lakes and Murray Mouth in drought conditions under the draft Basin Plan.

The modelling suggests that under the draft Basin Plan, there is sufficient water available to avoid exceeding salinity thresholds for the Coorong's south lagoon, mitigate most peak salinity periods in the north lagoon and to keep the Murray Mouth open 89% of years.

Surface Water Reductions

The NFF has recently suggested that the reduction being proposed in surface water (in the draft Basin Plan of 2750 GL) is around 33%. To calculate this they are estimating that 20% of water use in the Basin is not for agricultural purposes, and will, therefore, not be included in the recovery of water for the environment.

The MDBA disagrees with this. Under the draft Basin Plan, water can be recovered from any current type of water use, including interception. However, there are some types of water use that are unlikely to be recovered under the current bridging the gap activities. If we look at excluding all interception activities then the reduction in surface water diversions, is around 25%. If we further exclude water diversions for urban use and unregulated diversions then the proposed reductions in surface water diversions increases to around 27%.

Previous water recovery effort

Recent comments suggest that the draft Basin Plan does not take previous water recovery efforts into account. In the 'Delivering a Healthy Working Basin' document we show how we have taken water recovery efforts by communities and government into account since 2004: the year the National Water Initiative was introduced.

Since 2005, 960GLs per year have been recovered for the environment through programs such as The Living Murray, Water for Rivers and Water Sharing plans. 136GL per year is returned to the Snowy River system leaving 823GLs per year for the Murray Darling system. A figure explaining environmental water recovered to date follows:

Figure: Environmental water recovery

To listen to the Chair of the Authority, Craig Knowles, explain how we have taken previous water recovery efforts into account please click here.

Job Impacts

An article on page 1 of The Australian (29th November 2011) includes a table attributed to the NSW Irrigators' Council and the Victorian Farmers Federation. Information in the table lists incorrect figures for the sustainable diversion limits for each catchment. The correct figures are here.

The table refers to 'water cuts' but does not include the recovery to date and the amount of water that remains to be recovered and so has the potential to confuse readers about actual remaining reduction to be achieved over the next seven years. For example, some people from the Lachlan believe that there needs to be further recovery in their valley whereas it is clear in the MDBA's figures that there is no further recovery required.

The table also includes misleading figures on 'current water use allocations', which are substantially different from the amount of water used in each catchment. For example, the table lists the 'current water use allocation' of the Condamine-Balonne as only 118 GL a year and states that more water needs to be recovered than is currently used. However, the actual figures for the Condamine-Balonne is 978 GL a year with a remaining 95 GL of water to be recovered.

Estimates of job losses are contradicted by the independent studies we commissioned from experts from Monash University and ABARES . We've summarised the employment impacts these experts predict as part of our synthesis report (Part A, pages 81-84) on all of the socio-economic studies. Here's an excerpt from that report:

Short-run employment effects14 (14 All jobs estimates calculated using 2006 ABS Basin employment figure of 921,300.)

4.44 In the short run (i.e. until approximately 2015), taking into account the water reductions and the offsetting construction stimulus effect from infrastructure investment and buyback proceeds:

• Monash University modelling estimates that employment could be approximately 0.22 per cent higher (around +2,000 jobs) when compared with baseline employment.

• ABARES modelling estimates that the short-run net effect could increase employment by 0.33 per cent (approximately +3,000 jobs).

4.45 In the short run, if we ignore the offsetting construction stimulus effect from infrastructure investment and buyback proceeds:

• Monash University modelling estimates that employment could be approximately 0.03 per cent lower (around -300 jobs) when compared with baseline employment.

• ABARES modelling estimates that the short-run net effect could reduce employment by 0.05 per cent (approximately -500 jobs).

Long-run employment effects

4.48 In the long run—after the construction stimulus effect has dissipated - Monash University estimates that employment will be 0.17 per cent lower (around -1,600 jobs) if the buybacks proceeds are not reinvested in the economy and 0.08 per cent higher (around +700 jobs) if the buyback proceeds are reinvested (Wittwer 2011a). ABARES (2011d) estimates that employment will be 0.03 per cent (around -300 jobs) lower if buyback proceeds are reinvested.