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Review of the 1999 ACT Environmental Flow Guidelines: A report by the CRCFE to Environment ACT


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Ogden, R, Davies, PE, Rennie, B, Mugodo, J and Cottingham, P 2004 , Review of the 1999 ACT Environmental Flow Guidelines: A report by the CRCFE to Environment ACT.

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1) This is an ecological review of the 'ACT Government Environmental Flow
Guidelines' (1999) (or EFG). The EFG are a statutory document that
establishes the water requirements in streams and lakes in the ACT, to ensure
aquatic ecosystems are sustained. The CRC for Freshwater Ecology has been
asked to provide advice on the efficacy of the EFG, and on improvements that
can be made in the general approaches and actual flow rules for sustaining
ecological values.

2) The approach taken in the review is to assess the effectiveness of prescribed
environmental flows by reference to monitoring data and research on rivers
within the ACT, and by consulting with local scientific experts. Advice is
provided on the retention of current flow practices, or their modification to
better achieve ecological objectives. This information could contribute to
adaptive management in the near term, or to a more systematic formulation of
environmental flow guidelines, should that be undertaken in the future.

Performance of the environmental flow guidelines
3) The performance of environmental flows needs to be considered in reference
to objectives that reflect catchment uses as well as river condition. The
approach taken in this review is to judge sustainability in reference to
established �performance criteria� where they exist.

4) In regulated parts of the Cotter River system the current EFG low-flow levels
(supplemented by unmanaged reservoir spills and inflows), are delivering
many desirable ecological benefits. General river condition is at or above
levels specified in performance criteria, and appears to have improved since
the implementation of the EFG, despite the drought and fires. Both Macquarie
Perch and Two-spined Blackfish have successfully spawned during the

5) Adaptive management principles embedded in the EFG, and further developed
in practice, worked well in the Cotter River during 2003/04 in relation to
setting environmental flows during drought and under a demonstrated needs
scenario, as well as in relation to capturing new information.

6) In the Queanbeyan River downstream of Googong Dam the current EFG are
maintaining conditions at or above performance criteria levels.

7) The monitoring data are insufficient to determine the ecological value of
environmental flows in other systems.

Advice on retention of or changes to guidelines
8) A process of setting clear ecological objectives could be considered for all
river types and reaches within the managed area. The process could target
CRC for Freshwater Ecology ACT e-flow guidelines review systems with tailored environmental flows, and could involve focused
monitoring to allow assessment of performance against the objectives.

9) This review provides draft ecological objectives, arising from a workshop held
as part of the review. The review also proposes environmental flows that
should achieve the objectives, or that can be trialled.

10) Some suggestions are made for changes to existing environmental flows,
including introducing flow variability in releases from the dams, major
refinements to flushing flows, and a reduction in the flow required for fish
spawning in the Cotter River.

11) Continued integration of environmental flow management, monitoring and
assessment, within an adaptive management framework, will lead to ongoing
benefits. Consideration should be given to having clearer formalisation of an
active adaptive management strategy in the EFG.

12) Monitoring of the effectiveness of environmental flows to areas beyond the
water supply reaches should be considered.

Item Type: Report (Technical Report)
Authors/Creators:Ogden, R and Davies, PE and Rennie, B and Mugodo, J and Cottingham, P
Keywords: Australia, freshwater, environmental flow, ACT, EFG
Publisher: CRC for Freshwater Ecology & Freshwater Systems
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