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Objective

Recommendation

Key issues

What has been achieved 1998-2003

Tasmania Together

Related Issue Reports

Objective

To ensure that cumulative consequences of water storages and structures on downstream users and ecosystem services are included in decision-making.

Recommendation

It is recommended that:

• cumulative impacts of farm dams are taken into consideration as part of dam approvals processes and water management planning;
   
• a multi-agency database of water infrastructure (e.g. dams, weirs) is established to record the location and status of water infrastructure;
   
• an assessment of the need, priorities and mechanisms for removal of redundant in-stream structures is undertaken; and
   
• field checking and validation of actual dam numbers and capacities is undertaken.
   

Key issues

Supporting information for this recommendation is contained in Water Quantity and Water Use and Land Use and Inland Waters. There are also relationships between water storages and structures and a number of other sections in the Inland Waters and Wetlands Chapter. For example. Aquatic Health is dependent on cumulative consequences of decisions taken about water storages and structures.

The effects of water storages and structures, and extraction, can include the alteration of river flows and groundwater levels to a degree that is not sustainable for dependent aquatic ecosystems and human use. Natural hydrological processes in a catchment can be disrupted, influencing both surface and groundwaters and their connectivity. Rivers in Tasmania are already often highly fragmented because of existing structures.

Flow regimes are often a trigger for reproduction and any change to the natural regime can influence the reproductive cycles of affected flora and fauna species. In-stream structures, such as dams and weirs, often represent a physical barrier to fish movement, and sediment and nutrient transport. They can also create conditions that are more suited to algal bloom development or favour the establishment of introduced species. A changed flow regime through river regulation can also affect the geomorphology of river systems, for example, by changing channel width and rates of erosion and scouring.

As at September 2002, the WIMS database registered 5,516 existing dams (both in-stream and off-stream) for irrigation, stock and domestic uses. Since the last SoE Report (SoE), some 900 dams have been approved, although the majority of these are listed as having a dam status as 'proposed' rather than 'existing'.

What has been achieved 1998-2003

A new assessment process for dam construction permits under the Water Management Act 1999 has been established, which applies to both to small and large storage construction.

Tasmania Together

Relevant Tasmania Together goals and standards for 'Inland Waters and Wetlands' are listed in the linked file. The Tasmania Together Progress Board reported on progress toward targets for benchmarks set (Tasmania Together Progress Board 2003). Indicators, targets and baseline data are available in the latest Progress Report June 2003. Further information, including progress report updates, is available from Tasmania Together.

Related Issue Reports