The science of environmental flow assessment is one that has evolved very rapidly over the past five years. Over this time, the significance of the various aspects of the flow regime for components of the river ecosystem has been recognised, although our understanding of these relationships is still developing. In addition, it is understood that there is no magic number for ensuring that riverine ecosystems are sustained. Any extraction of water puts the river system at some risk. The more water abstracted, the higher the risk of environmental damage.

Given this, the following principle has been adopted as a precaution to assist with the assessment of environmental water requirements:

• An environmental flow regime should retain and/or reinstate as many of the features of the natural flow regime as possible.

In 2002, Victoria’s approach to assessing the environmental water requirements as part of the water allocation process was reviewed and updated, resulting in ‘FLOWS – A method for determining environmental water requirements in Victoria’.

The FLOWS method describes key flow components as part of a recommendation for an environmental flow regime – rather than a minimum flow recommendation. The key elements of the FLOWS method are:

• the use of flow components to examine a flow regime
• a documented objective setting process that links environmental objectives to flow objectives and recommendations
• the use of a multidisciplinary environmental flows technical panel
• the definition of key hydrological tools for analysis
• the use of a hydraulic model as a tool in the interpretation and development of recommendations.

The FLOWS method incorporates a degree of flexibility to ensure appropriate detail is applied for different systems. Adoption of this standard approach across Victoria ensures consistency between assessments.

The FLOWS method has been used extensively in various parts of the state as a key input to Victoria’s water allocation program.