Australian Capital Territory - environmental water provisions
In the Australian Capital Territory , the Water
Resources Act 1998 requires environmental flows to be defined
for all waterbodies in the Australian Capital Territory . The Australian
Capital Territory has also released a policy document Think
Water Act Water as part of an overall water resource strategy.
Environmental flows are defined in guidelines that were first produced
in 1999. The guidelines were reviewed in 200506 to produce the current
2006 Environmental Flow Guidelines.
The guidelines set out the volumes and timings of environmental flows and abstraction
limits in streams, rivers, lakes, and aquifers.
The single set of guidelines that cover the whole of the Australian Capital
Territory has been developed using the most up to date scientific information
available, and will be used with the Water Resource Management Plan Think
Water Act Water to manage Australian Capital Territory water resources.
The environmental flow guidelines apply to all rivers and streams in the Australian
Capital Territory , although specific rules have been set for only a subset
of rivers. The 2006 Environmental Flow Guidelines replace the 1999
Environmental Flow Guidelines .
To account for natural variability, the 2006 Environmental Flow Guidelines include
protection of particular components of the natural flow. These are baseflow,
small floods (riffle maintenance flows), larger floods (pool or channel maintenance
flows), and special purpose flows. Special purpose flows can be used to provide
flows for specific ecological needs, such as fish breeding events, but none
is currently specified in the guidelines.
Environmental flows are provided either by releases or spills from dams, or
by putting restrictions on the volume of water that can be abstracted from
a subcatchment. Environmental flow volumes are allocated before other uses.
Abstraction rules are also applied to ensure that licensed abstractors do not
impact on rivers during very low flow periods.
Ecological objectives for rivers and streams allow specific ecological values
to be protected by components of the environmental flow regime. In addition,
ecological objectives can be used to assess the effectiveness of environmental
flows, and the information used to refine the guidelines. The ecological objectives
and indicators of these objectives identified in the guidelines are based on
advice from the Cooperative Research Centre for Freshwater Ecology. For example,
an ecological objective for the Cotter River reach between Bendora Dam and
Cotter Dam is to maintain populations of the endangered fish species Macquarie
Perch. An indicator of success in meeting this objective is that more than
40 fish are captured in a standard monitoring effort.
Environmental flows in the various types of catchments are as follows:
- water supply catchmentsflows specified for these catchments
are based on extensive research and monitoring and are the minimum requirement
for healthy aquatic ecosystems to ensure that both water supply and conservation
objectives can be met. Special rules for drought periods recognise that,
when the urban population faces water restrictions during dry times, it is
appropriate that environmental flows also be reduced without impacting on
aquatic health, particularly the two endangered fish species that live in
the Cotter River
- urban catchmentsthe guidelines identify the natural baseflow
and channel maintenance flow that should be protected, and recommends that
the additional runoff from urban development be made available for abstraction.
This serves the dual purpose of protecting streams from unnaturally high
and permanent flows, and allows more use of second-class water in the urban
- other catchmentsenvironmental flow requirements are also
set for streams in natural ecosystems, such as those within Namadgi National
Park and Tidbinbilla Nature Reserve, and in modified ecosystems in rural
areas. The guidelines for these systems are designed to protect the baseflow
and also protect most of the volume of flood flows that are necessary to
maintain the channel form. In these catchments, limiting the quantity of
water that can be abstracted protects environmental flows.
The linked map shows the status of environmental water provisions throughout
the Australian Capital Territory for each surface water management area.
A map for environmental water provisions for the Australian Capital Territory
can be downloaded from the Maps environmental water provisions section.