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Environmental flows

Abstraction of supply water and run-off from disturbed surfaces (rural or urban) can place endangered and vulnerable aquatic species in and ecosystems of the ACT’s waterways at increased risk due to changed conditions.

Water quality and flow can be maintained by releasing ‘environmental flows’ downriver. Environmental flows often mimic the natural flow of rivers and streams. They generally consist of a base flow, smaller and larger floods, and special purpose flows (e.g. water released to maintain fish refuges during drought). They may comprise water released from dams or be a protected portion of the natural flow. Environmental flows are used for protecting aquatic habitats of plants (e.g. plants that require regular inundation on the floodplain) and animals (e.g. profiding flows for Macquarie perch breeding).

  • In water supply catchments, emphasis is on ensuring a natural level of water is allowed to flow in the river and that this water has comparable temperature and chemical characteristics to a natural flow.
  • In disturbed catchments (rural or urban), emphasis is on reducing pollutant levels (gross, fine and nutrient) and ensuring that streams do not suffer from excess of flood conditions. Design of urban impoundments in the ACT does not enable release of environmental flows and most are managed so that they are generally full with an equivalent amount of water to that entering being released downstream. Water released from the base of these pools is quite detrimental to the environment. Downstream flows are augmented by flows from urban tributaries.

More information is needed about the particular needs of some species and community education is required to help people understand the multitude of factors involved.

Achievement of this target will ensure that the environmental flows necessary to support water ecosystems are released. Existing environmental flow guidelines set objectives (with respect to macro-invertebrates, sediments and, in some cases, populations of endangered species) for rivers in the ACT depending on whether they are natural, modified or built by people.

Success of environmental flow regime in Cotter River

Since introduction of managed environmental flows in the Cotter River, both Macquarie perch and the two-spined blackfish have successfully spawned.

Environmental flow regimes objectives

All rivers, streams and created ecosystems

  • To maintain healthy ecosystems, prevent degradation of habitat and loss of macrophytes

Corin Dam to Bendora Reservoir

  • To maintain populations of the two-spined blackfish; and population numbers and distribution of the Cotter River frog

Bendora to Cotter Reservoir

  • To maintain populations of Macquarie perch and the two-spined blackfish

Below Cotter Reservoir

  • To maintain populations of Macquarie perch
TARGET 12. Environmental flows
Intermediate
  • The ecological objectives in the environmental flow guidelines are achieved (2015)
    • Long-term
  • The ecological objectives in the environmental flow guidelines are surpassed (2030)

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    Molonglo Catchment Group

    Molonglo Catchment Group The Molonglo Catchment Group works largely in NSW and covers the catchments of the Molonglo and Queanbeyan Rivers, Jerrabomberra Creek and the urban areas of inner Canberra and Queanbeyan.

    Ginninderra Catchment Group

    Ginninderra Catchment GroupThe Ginninderra Catchment Group works in the urban areas of Belconnen, West Belconnen, Hall, Gunghalin, and the rural areas and nature reserves of the Ginninderra Creek catchment.

    Southern ACT Catchment Group

    Southern ACT Catchment Group The Southern ACT Catchment Group operates in the southern areas of the ACT covering Woden, Weston Creek, Tuggeranong, Tharwa, Tidbinbilla, the Cotter Road, Namadgi National Park and related rural areas.
    Theme by Dr. Radut.