This June, a pattern of more than 50 years has quietly continued, leaving the upper Wannon River ‘stranded’ in its time of need

For regular readers of the NGT newsletter, you might recall that we initiated a discussion earlier in the year about the impact of the diversions on the headwater streams of the upper Wannon River. We did so in the context of the unprecedented situation we face this year, where the entirety of the Wannon River in the Grampians National Park below the diversion points, burned in the bushfires last summer. This is something that locals told us has never occurred before, and includes a highly biodiverse former refuge area across the Wannon alluvial fan – just upstream of Brady, Gooseneck and Walker Swamps.

Background

To re-familiarise yourself with this issue, you can read those past stories via the links below:

• In the wake of the Grampians bushfire, will the Wannon River get the water it needs?
• Wannon River diversions – your questions answered: Radio interviews, a diagram and video bring the issue into focus

Alternatively, to help briefly paint the picture, an annotated oblique aerial diagram (to illustrate how the diversions operate) is also shown here:

These diversions – which have been in place for over 50 years, since 1971 – are operated between the 1st June and the 30th October each year, resulting in the bulk of winter and spring flows in the First and Second Wannon Creeks above this point being diverted away from the river and ending up in storage within the Lake Bellfield dam.

This is a key issue for both the Wannon River and Lake Bellfield, because Mt William and the Major Mitchell Plateau are at the highest elevations in the Grampians with the most reliable rainfall and generate runoff at many times when other locations at a lower elevation miss out.

NGT’s request of the Victorian Government – and the outcome

NGT wrote to the Hon. Gayle Tierney MP, the Victorian Minister for Water, back in January, and we have been waiting patiently for an answer about whether the diversions could be placed on hold this year, to give the river access to its full catchment to facilitate its post-fire, and now drought-impacted, recovery. From questions I have been asked by many people since then, I know that a number of our readers have also been awaiting news of the outcome of NGT’s request.

After the long wait, last week I was formally advised by a staff member in DEECA, the Department responsible for supporting the Water Minister, that – despite the best of intentions of a number of different agencies involved, who carefully assessed the issue – the request to alter the operating rules for the Wannon Diversions this year has been refused.

Given that the case for temporarily reinstating Wannon River headwater stream flows is never likely to be stronger that right now, based on the combination of bushfire and drought impacts that we are witnessing this year, I have been doing my best over recent days to understand precisely how and why this decision was made, and crucially, whether we have any further options that might still be pursued.

This is now also a race against time, as winter is upon us and the diversion offtake pipes have been back open and operating since the beginning of the month. This means that each and every day it rains on the Major Mitchell Plateau this winter, the flows being generated are being lost to the fire-affected and drought-impacted – now essentially ‘stranded’ – reach of the Wannon River downstream.

Exactly how are these water management decisions made?

There are a set of operating rules in place (see here to learn more) that, to put it clearly and simply, since 1971, have prioritised water harvesting from the Wannon Diversions for Lake Bellfield over the needs of the Wannon River downstream of the diversions. This means that ‘water sharing’ with the Wannon River during this period annually, can literally only occur when the volumetric capacity of the diversion points is temporarily overwhelmed during higher flows, meaning that all low-moderate flows are captured and directed to Lake Bellfield. [As a side note, it is interesting that this scenario is the exact reverse of many modern waterway restoration projects, where ‘low flow bypass’ structures are increasingly being used to better protect and manage high priority streams that have been starved of flows by instream structures (like dams or diversions).]

As I have now discovered, any attempt to seek a change to these operating rules is fraught, involves a lot of parties and is quite a complicated process, so perhaps the simplest way to describe how water storage management decisions are made and/or reviewed in the Grampians, is to show you the diagram below, from the Wimmera-Glenelg System ‘Storage Manager’ website.

My understanding is that the four Water Entitlement holders in the Wimmera-Grampians system shown in the framework above, are all required to agree to any proposal that would alter the diversion rules for the upper Wannon, because any ‘loss’ of water that would otherwise have entered Lake Bellfield (despite that water being taken from another river’s catchment) still has to be accounted for, and therefore an equivalent reduction would need to be borne by one or more of the Entitlement Holders. These four Entitlement Holders (GWMWater, Coliban Water, Wannon Water and the Victorian Environmental Water Holder) are Victorian Government entities that each have different remits, responsibilities and functions, including things like providing water for towns, rural customers and environmental flows.

In this case, I have been advised that the four Entitlement Holders were not able to come to unanimous agreement about a temporary change of the diversion rules this year (which apparently is required for such a decision to take effect), on the basis that the marginal impact it might cause to their own allocations for other purposes was considered unacceptable (at least in the case of one or more of these entities). Further, and adding another layer of complexity and uncertainty, is the fact that the precise amount of water that would be involved in this water accounting exercise is currently unknown, because the diversion volume is not ascertainable in advance; i.e. no-one can predict how much rain will fall on the Major Mitchell Plateau this year.

These water Entitlement Holders are no doubt and understandably feeling especially cautious and risk-averse at a time of prolonged drought and ongoing climatic uncertainty. However, from NGT’s perspective, it also seems like a rare, pivotal moment and opportunity to show collective leadership and focus on the bigger environmental picture for the Grampians National Park was lost.

Although this is an extremely disappointing outcome, we have not given up just yet.

Where to next?

NGT is now carefully considering the options for how we best respond to this recent news, but in the interests of transparency, are immediately sharing this important update with our community of supporters and newsletter subscribers.

The reality now is that we must accept that the specific avenue outlined above, where the Entitlement Holders themselves could have temporarily agreed to modify the operating rules, has failed. However, we also understand there may also be other pathways – at both the Ministerial and operational level – that could still be pursued, and that could conceivably achieve a more balanced or nuanced outcome than the status quo.

As this is all still very fresh news as I write this article, we’ll provide a further update in a future newsletter, when we have more information to share. But rest assured that despite our disappointment, we’ll continue to work constructively with the various agencies involved, to see if an alternative pathway to a common sense outcome is possible. As I am sure you’ll agree, the future health of the Wannon River and the biodiversity values of the Grampians National Park are certainly worth the effort!

Finally, to remind you of what the diversions look like, here is the video I shared back in January (of the First Wannon diversion operating in October 2024) to refresh your memory…