Overview of 2025/26

The delivery program operated to the dry scenario (Seasonal Watering Plan 2025-26) during winter/spring and early summer/autumn to present. This was due to flow conditions reflecting rainfall and streamflow deficits accumulated from summer/autumn in the previous water year.

Dry conditions experienced in summer/autumn 2025 continued into winter and early spring. During winter, mean maximum temperatures were above average across the catchment, with rainfall and streamflow below average (Melbourne in Winter 2025).

Above-average monthly rainfall totals were accumulated at the end of October through November, leading to the spring season ending with above-average rainfall totals (Melbourne in Spring 2025). However, this masked underlying rainfall and streamflow deficits experienced throughout most of the season, which aligned with the dry operating scenario.

Environmental water delivered in 2025/26

Winter/spring

Very dry catchment conditions led to low unregulated achievement of winter/spring low flow targets at reach 2 (Drouin West). In contrast, reach 6 (Iona) experienced near full compliance for winter/spring low flows, in part due to increased tributary contributions.

A partial winter/spring fresh was also achieved for reaches 2 and 6 via unregulated flows.

A target 1 of 1 winter/spring freshes was achieved for reach 2, with the active delivery of water for the environment in August.

Summer/autumn

Continuing dry conditions in summer/autumn minimised unregulated contribution to low flow targets, leading to a period of low flow supplementation in January to support reaches 2 and 6.

Unregulated flows in December 2025 led to:

• 1 summer/autumn fresh for reach 2
• 2 summer/autumn freshes for reach 6.

A summer/autumn fresh delivery is currently underway at time of writing.

A further summer/autumn fresh is planned for reach 2. An autumn high and low flow supplementation may also be delivered depending on seasonal conditions.

Key environmental values

In the Tarago-Bunyip River system, water for the environment supports the following key environmental values.

Opportunities for shared benefits are also incorporated into planning and watering decisions, if they do not compromise environmental outcomes.

Potential watering actions

We plan for all climatic scenarios. Below are the proposed environmental watering actions for the Bunyip-Tarago Rivers in 2026/27 under an ‘average’ year scenario:

• Summer/autumn freshes
  
• Autumn high
• Winter/Spring low
• Winter/spring fresh
• Summer Autumn low