Selected Highlights from the Guide to the Murray-Darling Basin Plan

 

 

Introduction:

The Guide to the Murray-Darling Basin Plan presents Sustainable Diversion Limit proposals for surface water and groundwater that balance the environmental water requirements with the potential social and economic impacts in line with The Water Act 2007. They then developed proposals for transitional arrangements to support communities, individuals, industries and businesses to make the transition to the SDLs, when finalized.

The amount of surface water diverted for consumptive use such as towns, industry and irrigation has increased from about 2,000 GL/y in 1920 to entitlements of approximately 11,000 GL/y in the 1990s.

However, the impact of drought over the past decade has seen actual diversions drop significantly.

The combination of drought and historic diversions means that there have been no significant flows through the Murray Mouth since 2002.

How water is currently shared between the environment and consumptive uses:

This analysis shows that:

• The long-term average rainfall for the Basin is about 500,000 GL/y

• The amount of rainfall that ends up in the river system, which is referred to as inflow, is about 32,800 GL/y and for groundwater recharge is about 26,500 GL/y.

• The average amount of that inflow that is used for consumption is 15,400 GL/y. This is made up of 13,700 GL/y surface water and 1,700 GL/y groundwater.

• Surface-water use is made up of 10,940 GL/y taken from watercourses and floodplains (watercourse diversions) and 2,740 GL/y is taken by farm dams and plantation forestry. This second category is generally referred to as interceptions and these are generally not as closely regulated.

• The long-term average amount of water that would flow through the Murray Mouth if there was no development is about 12,500 GL/y. Although this is highly variable, on average, 83% of this would come from the Murray system and 17% would come from the Darling system.

• At present, with current levels of development, the long-term modeled average amount of water flowing out of the Murray Mouth is about 5,100 GL/y.

Social and economic affects considered when modelling SDL’s:

• Depending on the actual size of the reduction in current diversion limits, this could have serious effects on some communities. Any reduction in water availability will affect communities.

• Industries with high water usage but lower or more volatile value products such as broadacre cereals, rice and cotton will be more severely impacted than other industries with higher value products such as grapes, nuts and fruit.

• Those regions with a relatively high dependence on irrigated agriculture would be expected to experience a larger reduction in economic activity compared to regions with more diverse economic activities. The regions expected to experience the greatest reduction in economic activity are Murrumbidgee, Moonie, Goulburn–Broken and, to a lesser extent, Condamine–Balonne, Murray (in all three states), Macquarie, Campaspe and Loddon.

• Smaller towns with heavy dependence on irrigated agriculture could experience greater social and economic implications due to their dependence and the lack of alternate industries.

• Severe and prolonged drought across the Basin (from 2000 to 2009) has resulted in a sustained period of substantially reduced water available for economic purposes. This has adversely affected the cash flows and capital and increased the debt levels of farms, households and businesses in the agriculture, forestry and fishing industry and related sectors.

• A significant proportion of Basin communities appear to have sufficient diversity of economic activity and social capital that they will be relatively resilient to the proposed reductions in diversions.

Several regions appear to be at a relatively higher risk of substantial social impacts, including in the north-east of the Basin, the Border Rivers, Gwydir, Namoi and Macquarie Castlereagh regions and, in the southern Basin, the Lachlan, Loddon, Murrumbidgee and Murray regions.

The Authority is particularly concerned about the potential flow-on effects to communities, industries and individuals in key areas. Given the dependence on water availability and the diversity of regional economies, some industries, businesses and communities would be more severely affected than others.

In the short and long term, sectors most adversely affected are likely to be irrigated broadacre agriculture (e.g. rice, cereals) where reductions in gross value of irrigated agriculture production may be greater than 30%. Cotton is likely to incur a reduction in gross value of irrigated agriculture production of around 25%, dairy around 10%, and horticulture less than 5%.

All catchments would be likely to experience reductions in economic activity at least in the short to medium term, with the greatest percentage reductions estimated to occur in the Moonie, Gwydir and Barwon–Darling regions in the northern Basin, and the Murrumbidgee, Loddon and Murray (NSW Murray) regions in the southern Basin. Depending on the local communities’ capacity to adapt, these regions would also be likely to be the most at risk in terms of adverse social impacts.

Conclusion

Based on the above analysis the Authority has made a number of critical judgments in developing these proposals.

1)
· The Authority decided only to examine scenarios for setting surface water SDLs at the lower end of the range of additional water needed for the environment (that is the lower end of the 3,000 GL/y to 7,600 GL/y range).

· The Authority believes reductions that exceed 4,000 GL/y will not meet the requirements of the Water Act. Indeed, reductions of this size would not represent an optimisation of the economic, social and environmental outcomes under the Water Act. The Authority therefore determined that it would only examine scenarios with reductions of between 3,000 GL/y and 4,000 GL/y.

2) The SDLs will be applied to:

• Watercourse diversions — including diversions from watercourses to provide water for towns, community water supplies and irrigators and industries. These are normally provided by a system of entitlements administered by Basin states through water resource plans. Watercourse diversions also include floodplain harvesting which is normally included in water resource plans

• Interception activities — including uses such as farm dams and forestry plantations.

With the release of the Guide, it enables stakeholders to provide feedback to the Authority on its proposals. Feedback can be provided through regional meetings, by letter, or through the Murray–Darling Basin Authority website.

With the release of the Guide, it enables stakeholders to provide feedback to the Authority on its proposals. Feedback can be provided through regional meetings, by letter, or through the Murray–Darling Basin Authority website.