Sustainable yield relative to surface water cap
Understanding the relationship between sustainable yields and surface water
caps is critical to understanding the status of surface water management in
Australia . In a water management area with a cap set at or below the sustainable
yield, then it is expected that development within that cap could be supported
on an ongoing basis, pending any future impacts on the level of resources.
In an area with a cap above the sustainable yield, then the current level of
development cannot be supported and the cap and all entitlements to water will
have to be reduced.
Nearly half of the water management areas in Australia have a cap, with more
than a third of these being provisional caps; the rest are absolute caps. Most
caps have been assessed since 1997, and many have since been re-assessed to
determine whether they allow for environmental water requirements (refer to
Environmental water provisions).
Australian Capital Territory
The Australian Capital Territory has one surface water management area, which
is capped within the sustainable yield volume. This cap was assessed in 1999.
New South Wales
In New South Wales, reducing the level of entitlements back towards the sustainable
yield is included in the water sharing plans by introducing a plan limit for
extractive use. A number of surface water management areas in New South Wales
are highly developed, and most of these areas will come under either macro
water plans or water sharing plans during the next five to 10 years.
Northern Territory
Sustainable yields have been determined for all surface water management areas
in the Northern Territory . The volume of sustainable yield is extremely variable,
with six surface water management areas having a sustainable yield less than
eight gigalitres per year in the arid south of the Territory, while 27 surface
water management areas located in the north of the Territory have a sustainable
yield in excess of 100 gigalitres per year. The area caps in all surface water
management areas in the Northern Territory , with over two thirds being absolute
caps, and the remainder are provisional caps. In most cases this is because
there is little resource to assess.
Queensland
Queensland has 20 capped surface water management areas—seven of these are
absolute caps, and another 13 are provisional caps. The sustainable yields
have not been assessed in Queensland and so the relationship to the caps cannot
be reported.
South Australia
Sustainable yields are not always relevant in South Australia because these
are not representative of the management regime in place. Caps have been determined
for prescribed areas only, but they are applied using a rules-based approach
(except for the River Murray), with development (farm dams) and extraction
considered prior to any granting of an allocation in systems that have not
reached the sustainable usage limit. Rules can include:
- an allocation that is based on a rate of extraction above
certain threshold water levels (e.g. Morambro Creek Prescribed Watercourse
Area)
- a percentage rate of capture of runoff (e.g. Eastern Mt Lofty
Ranges)
- using sustainable usage limits for extractions in individual
subcatchments which are below caps (e.g. Clare Valley Prescribed Water
Resources Area ).
Areas under a ‘notice of intent to prescribe' have a moratorium placed on
development (a provisional cap) to limit further extraction until developments
and existing allocations are determined and rules developed. The four prescribed
areas have an absolute cap, which represents sustainable yield. The sustainable
yield for the 18 surface water management areas in South Australia with provisional
caps have preliminary values and are being further investigated.
Tasmania
Tasmania has 38 surface water management areas with a cap on surface water
use and abstraction. In each case, the cap is considered to be below the sustainable
yield in all surface water management areas where the sustainable yield has
been determined, with the exception of the Clyde Surface Water Management Area,
which is considered to be at the sustainable yield. None of the surface water
management areas in Tasmania is considered to have a cap that is above the
sustainable yield.
Victoria
Victoria did not consider the sustainable yield volume to be representative
of the sustainable management regime that is used in each surface water management
area. Nevertheless, a figure on sustainable yield was provided from which the
relationship to caps could be ascertained. Qualitative information that was
provided on the caps indicated that, where reaches are flow-stressed, there
are specific targets being set under water recovery projects to improve the
environmental water reserve. Where the cap is considered to be above the sustainable
yield, management actions are in place to bring the cap down to the sustainable
yield through the sustainable
water strategies currently being formulated for
different areas of Victoria.
Western Australia
Sustainable yields have been determined for all surface water management areas
in Western Australia .
The accompanying map illustrates the surface water management areas for which
sustainable water yields have been determined and compares these to the caps
set in those areas.
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Surface water sustainable yield as compared to the
cap. |
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Surface water sustainable yield as compared to the cap. (1.6 Meg )
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