Water Management
Environmental monitoring in regulated rivers
The term 'regulated river' is a legal term under the Water Management Act 2000 that applies to rivers where downstream flows are regulated by a major storage, or dam, to supply irrigation water. Many other rivers in NSW have modified flow regimes attributable to water storages but they are not legally defined as regulated rivers, eg. the Hawkesbury-Nepean River.
Environmental flow rules
As environmental knowledge and awareness grew in the 1990s, it was recognised that toxic blue-green algal blooms, loss of native fish and waterbird populations, rising salinity and other adverse environmental outcomes would become more prevalent in New South Wales unless water was shared in an equitable manner between extractive users and the environment. These problems were particularly apparent in regulated rivers.
By 1997 the NSW Government had introduced environmental flow rules in the regulated Gwydir, Namoi, Macquarie, Lachlan, Murrumbidgee, and Hunter River Valleys, as well as the Barwon-Darling River. Environmental rules were generally designed to provide water for the environment across a range of flow events, from floods to very low flows.
The environmental flow rules now form the basis of environmental water provisions within statutory water sharing plans, prepared under the Water Management Act 2000. Ecological benefits of these flow rules include reduced algal blooms, increased wetland biodiversity, more abundant native fish and more natural ecosystem processes.
Integrated Monitoring of Environmental Flows
The Integrated Monitoring of Environmental Flows (IMEF) program, established in 1997, is a systematic scientific program assessing the ecological benefits of the environmental flow rules. The program uses around 180 targeted sites on inland and coastal rivers to gather information and data.
The objectives of the IMEF program are:
- to investigate relationships between water regimes, biodiversity and ecosystem processes in the major regulated river systems, and the Barwon-Darling River
- to assess responses in hydrology, habitats, biota and ecological processes associated with specific flow events targeted by environmental flow rules
- to use the resulting knowledge to estimate likely long-term effects of environmental flow rules and provide information to assist in future adjustment of rules.
IMEF provides valuable scientific information needed to review and inform water sharing plans. The program also contributes to our broader knowledge and understanding of the biodiversity and ecological processes in all New South Wales rivers and wetlands. Managers of water resources gain reliable information that assists them to balance the many competing demands for river water, including environmental, recreational, domestic, agricultural and industrial uses. All members of the NSW community who use rivers and river water will benefit from more natural ecology in catchments and improved water quality in rivers.
The IMEF program is managed by the Department of Water and Energy, with support from Department of Primary Industries, university and Cooperative Research Centre researchers and both government and private analytic laboratories.
Current monitoring projects
- Wetting terrestrial organic matter (PDF 510 KB). This project is examining how environmental flows can improve the ecology of NSW's rivers by increasing the supply of dissolved organic carbon to nourish the aquatic food chain. Phase 1, 1998-2005 Report
- Ecology of the Murrumbidgee River (PDF 26 KB). This project assesses the ecological benefits of protecting natural low flows, and protecting or restoring a portion of the natural peak flows from Burrinjuck Dam to the Murrumbidgee River.
- Replenishing the wetlands of the Lachlan River (PDF 26 KB). The benefits of environmental flows for wetland habitat and biodiversity are being investigated in the Lachlan and Namoi Rivers and in the Macquarie Marshes and Gwydir/Gingham wetlands.
- Suppressing algal blooms and fish kills (PDF 26 KB). Stratification of temperature and dissolved oxygen within the weir pools of the lower Darling River is being monitored to investigate the use of environmental flows to avoid conditions that encourage excessive growth of blue-green algae, and kill fish by oxygen starvation.
- Survival of fish hatchlings (PDF 89 KB). This project is investigating the use of environmental flows released from dams to maintain the abundance of fish hatchlings when their survival is threatened by drought and unnatural patterns of water flow in regulated rivers.