The purpose of eFlow is to assist with the design of environmental flow regimes by augmenting the current flow regime so that it meets environmental flow requirements (e.g. seasonal base flows and event-based floods). eFlow allows the simultaneous consideration of many environmental flow components, and also allows the use of different augmentation strategies such as extending existing high flows, mimicking the natural frequency of the specific flow component and allowing multi-year return periods. eFlow includes the option of defining 'risk based' environmental flow criteria to allow the assessment of those years where environmental conditions are not quite met, although some environmental value has still been achieved. eFlow provides a measure of the water cost of delivering the environmental flow components, as well as a time series of the augmented flow.

eFlow is aimed at ecologists and eco-hydrologists responsible for devising or implementing environmental flow requirements and river operators involved in devising flow regimes.

eFlow is designed for users with expertise in environmental flows. The software itself utilises a step by step process, making it relatively easy to use without training.

A water management authority is presented with environmental flow recommendations for a given river reach with notable environmental values. These recommendations include the need for continuous seasonal flows that are above a particular threshold to maintain river health and a minimum number of flood events which are necessary to trigger seasonal fish spawning. The water management authority can then use eFlow to create a new daily flow regime that will meet the recommendations and to quantify how much extra water will be required.

The active allocation of environmental flows is a fairly young field that is open to interpretation. eFlow is one of the only dedicated environmental flow allocating tools available and provides a way of devising allocations in a consistent and robust manner.