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The proposed Macquarie Re-regulating Structure would have a major negative impact on the river ecosystem, reducing biodiversity and reducing native fish populations.  There are four major impacts:

1. Capture of tributary flows

All environmental water is not equal.  River flows that are uninterrupted by dams and weirs have extremely high ecological value, compared to flows that are stored in dams and weirs and re-released.

Uninterrupted river flows pick up nutrients (especially carbon such as dead eucalyptus leaves) and generate natural productivity of plankton, which is the essential food source of fish larvae.  This is the fundamental process of river ecosystems that sustains native fish populations.

If flow is uninterrupted over long distances, it has even greater ecological value as this enables fish that are a long distance downstream to detect the increasing flow (fish can sense the slightest increase in water velocity and have an extremely acute sense of smell) and migrate upstream to spawn so their larvae have greater survival.

The advantages of uninterrupted river flow are that: it occurs with a natural season; it has a natural rise and fall in river level; and it has natural, flowing water, hydraulics.  It also has no thermal pollution.  All these aspects contribute to these flows having high ecological value.

In the Macquarie Valley, tributary flows and rainfall events downstream of Burrendong Dam are one of the most valuable ecological assets that are presently sustaining native fish populations.  If the proposed regulator captures and re-regulates these tributary flows and main-stem flows that result from rainfall downstream of Burrendong Dam, native fish populations will have less successful breeding and populations will certainly decline.

The mitigation for this impact is to provide full transparency of tributary flows and rainfall downstream of Burrendong Dam.

2. Impacts of variable water levels on river-edge and channel habitats

Tributary rivers of the northern Murray-Darling Basin have highly variable river levels, from floods to droughts.  However, these water levels vary over a very consistent regime over time – rising in floods but spending a lot of time at a low level with varying baseflows.  The time-scale and season of this variation is very important for fish.  Nesting species such as catfish and Murray cod establish a nest in spring and if the water level drops too much and/or too quickly they abandon the nest and there is no spawning that season[1].  This is an insidious impact as it does not become apparent until many years later as old fish die out and are not replaced by young fish.

Gin Gin Weir presently has a stable water level, while the new regulator will have highly varying water levels that will vary over short times scales within an irrigation season.  These are likely to impact breeding of Murray cod and catfish.

Under natural conditions in non-flood times, there are relatively stable water levels with occasional pulses of flow.  These conditions enable aquatic plants to develop in rivers, which contributes to the basis for the food chain, and ultimately fish survival and ongoing populations.  Regulators with highly varying water levels have weirpools that are characterised by barren banks and river channels, devoid of aquatic plants.  This breakdown of the aquatic food chain results in less food for native fish, reducing their health, resilience, and survival.

3. Impacts on flowing-water habitats

Rivers have a natural mix of flowing and stillwater habitats.  Standing beside a healthy river, we all visually recognise flowing water and we recognise eddies, backwaters, pools and riffles – that is, healthy rivers have diverse river hydraulics (or hydrodynamics).

This hydraulic diversity provides habitat diversity and biodiversity.  There are aquatic animals and plants that specifically thrive in hydraulic diversity including: natural biofilms (fungi, algae, protozoa, bacteria), diatoms, plankton, aquatic insects, snails, mussels and fish.  The high biodiversity supported by hydraulic diversity supports a diverse food web, which contributes to resilience of the river ecosystem to withstand events such as droughts.

Weirs create backwater and pool-like conditions; where this happens and hydraulic diversity is reduced, biodiversity declines.  That is, some species become locally extinct – they cannot survive in the semi-permanent pool-like conditions.  Under natural conditions, prior to any dams or weirs, the Macquarie River could stop flowing and become a series of pools but only very rarely and for short periods of time.  Notably in 1902, in possibly the worst drought on record – the Federation Drought – when the Darling stopped flowing for 11 months at Menindee, the Macquarie River remained flowing the entire time.[2]

So flowing water habitats are a foundation of the Macquarie River ecosystem.

Two key species that thrive in flowing water are Murray cod and River mussel.  Murray cod are a valuable recreational fish and both species have high cultural and totemic value in aboriginal culture.  Many river mussels died in the last drought in the Darling River because there were no flowing water habitats for many, many months. Although adult Murray cod can survive in large pools, where there is good water quality, the survival of larvae and young fish is dependent on flowing water habitats and the diverse food webs that these provide.  Hence, to maintain the Murray cod population, flowing water and hydraulic diversity are essential to provide key nursery habitats.

The pool-like conditions that are created by weirs, not only reduce hydraulic diversity and biodiversity, but are also more favourable habitats for pest species like carp.

The proposed regulator will have three major impacts on flowing water:

1. upstream of the regulator the backwater will be much greater than the present Gin Gin Weir, creating more still-water conditions and inundating Murray cod nursery habitats and River mussel habitat;
2. as the level of the weirpool decreases upstream during the irrigation season, and more of the river channel is exposed, it will not have enough time to enable recolonisation of animals that specialise in this flowing-water habitat (e.g. aquatic insects, snails, mussels) – hence, critical food webs will not be established;

• the regulator will capture tributary flows and local rainfall events – therefore passing less flow downstream which will directly reduce the extent and duration of flowing water conditions.

Dr. Martin Mallen-Cooper

[1] Stuart I., Sharpe C., Stanislawski K., Parker A. and Mallen-Cooper M. (2019) From an irrigation system to an ecological asset: adding environmental flows establishes recovery of a threatened fish species. Marine and Freshwater Research 70, 1295-1306.

[2] Water Conservation and Irrigation Commission (1956) ‘Surface Water Supply of New South Wales. Stream Flow Records Period to 31st December 1950. Volume 1.  Darling River Basin ‘ (V.C.N Blight, Government Printer: Sydney)

Burrendong empties at blistering speed.

The dam is massive – 1,188 billion litres. For context, Dubbo draws 8 billion litres a year to meet 70% of town water needs.

Burrendong has nearly bottomed out three times. In the summer of 2019/20 plans were in place to suck the dead water from the very bottom of the dam before letting the river below Burrendong dry up.

The river below Warren was allowed to dry up, followed by massive deaths of native fish, turtle, mussels, and other wildlife. People below Warren were left with no access to water from the river for their domestic and stock needs. It was a tough time.

Burrendong empties so quickly because the rules in the water sharing plan allow it to.

Water that has not yet fallen as rain over the Macquarie catchment is sold in advance.

The credit rule is essentially allocating clouds – water that hasn’t even fallen in the catchment yet,” said Celine Steinfeld, lead author of the paper published in the Journal of Hydrology, and also a member of the Wentworth Group of Concerned Scientists. “It was clear that water in the Macquarie had been overallocated.” (SMH Clouds become water entitlements in ad hoc river plan, paper finds)

The NSW Government knows the Macquarie is over allocated. On page 89 of their 2014 State Infrustructure Strategy they explain that while Burrendong is one of the biggest dams in state, the irrigation industry has developed to a size where the natural capacity of the river has been exceeded. There is simply too much water being sucked out.

When working out how much water to sell every year, the NSW Government does not take into account any rainfall and inflow data from before 2004. They choose to only look at last centuries rainfall patterns when is was a lot wetter.

The re-regulating dam to make everything even worse

The NSW Government are planning to add to our problems by building a re-regulating dam at Gin Gin that will allow even more water to be extracted.

The purpose of the enormous gated dam is to get more control over water in the river and make more water available for general security users. The effect is to convert unregulated flow to regulated flow.

This dam will be a loss to the environment of about 25 billion litres a year, according to Tony Quigley, Chair of Macquarie Food and Fibre.

The most effective, common sense way to address water security issues in the Macquarie Valley is to look at the glaring problems with the rules in the water sharing plan, not to pour many tens of millions of public dollars into a monstrous structure that will only benefit a privileged few.

Mel Gray – 31/5/2020

From 2002 to 2008 my parents managed sheep stations along the Darling-Baaka River around the Tilpa area. During visits home when there was a flood event expected, I remember the fax machine would ring every morning with a warning – a rise in the river of xyz metres is expected in your area in xyz weeks’ time. Get prepared!

Growing up on our farm in the flood-zone of the Clarence River, the warning time for floods was days at best, and the impact to our lives and my parents business was all consuming. Like a well-oiled machine, we’d have the cattle and machinery to higher ground, the furniture lifted. Time to settle in and marvel at the awesome power of a Clarence River flood.

The gift that was left of thick rich fertile silt, up to several feet deep, would enrich and sustain the floodplain landscape, and my parent’s business, for years. The salt water that inevitably creeps up the Clarence for several hundred river kilometres in dry times, pushed well back out to sea. The nutrient rich floodwaters kick starting the web of life in the prawn and crab rich estuaries like the Broadwater and Wooloweyah Lagoon and the coastal recreational and commercial fishing grounds off the coast of Yamba. Sea food heaven.

Now out west, we looked forward to experiencing the mighty Darling Baaka in flood. So we’d wait. And wait, and wait. The river levels remained unchanged, after several weeks the faxes would stop.

Mum in the Darling Baaka at Tilpa, circa 2004

The floodplains remained dry, dusty, and without the rich covering of fertile silt. The rains that triggered the teasing faxes had fallen many hundreds of kilometres away. We’d heard stories of water skiing on the many enormous ephemeral lakes in the area. They remained empty. By now, almost two decades on, even the centuries old Red Gums are dying.

Since the 1990’s, floods along the Darling Baaka have become smaller and less frequent.  As a consequence the land, animals, people and economies have been dying.

The impact on First Nation communities is heart shattering. The average life expectancy for a male in Wilcannia is 37. The Baaka is the blood of the Barkandji People and without the river they are dying.

What is happening on the Darling Baaka is cultural genocide.

  ABC News April 2018, Wilcannia

I moved to the Macquarie Valley in 2011, and fell head over heels in love with the Wambuul Macquarie River and the amazing internationally significant Ramsar listed Macquarie Marshes.

I volunteered a lot of my time restoring the riparian zone around Dubbo with our local BushCare group.

Community tree planting day July 2017

I joined a kayak club and got to know the river and Marshes well. I started a grassroots community group, and became an environmental advocate.

The summer of 2019/20 was shocking in the Macquarie Valley. The sharp severity of the drought was unprecedented. The frequency and intensity of the dust storms was actually a little scary.

The Warren weir was raised by WaterNSW stopping flows beyond. Downstream, the river rapidly dried up to a series of disconnected green pools.

Macquarie River, 20km downstream of Warren NSW, November 2019

Insurance populations of turtles and fish were rescued from the river and secured in hatcheries by environmental agencies. Despite commendable efforts from the recreational fishing community to rescue as many fish as possible, mass fish deaths resulted.

The Macquarie Marshes were parched. There hadn’t been any surface water in the core Marsh since January 2019. The impact of years of ‘tight’ river management was evident – there was far less water around, and it disappeared very quickly.

Dead Red Gums, Macquarie Marshes August 2019

Critical human need and stock and domestic requirements had not been met along the creeks downstream of Warren or the Lower Macquarie.

There was a shocking loss of wildlife as a result. Mobs of kangaroos perished, many 50 year old plus turtles died, and we lost some of the oldest mussels known to exist in our fresh water rivers. The loss of vegetation meant less habitat for many and varied water dependent animals, fish and birds.

The North Marsh reed bed (the largest reed bed in the Murray Darling Basin) caught a lightning strike in October 2019 and about 5,000 ha was burnt.

North Marsh reed bed, October 2019

It was a tough time for the Traditional Owners and Elders, the landholders, recreational fishers, the whole community. It was a tough time to be an environmentalist.

We knew the reed beds need flood water ASAP. While they shot up after some rain fall that summer, we understood that they were using what little precious reserves their rhizomes held, making floodwater even more critical to their recovery.

The Rains Came!

The floods came in February 2020, entering the Macquarie in several events through the Bell, Little and Talbragar Rivers – all of which are downstream of Burrendong Dam.

Immediately, from the very first peak of the first flow, permission is given for water to be pumped under a licence type called “supplementary”. Supplementary access has the lowest priority of water access in the rules, and should only be allowed once critical human need, and stock and domestic requirements downstream had been met. However because the phrase FORECAST TO BE MET is in the rule, pumping was allowed. The critical environmental and human needs downstream were considered to be FORECAST to be met in several weeks time.

This anomaly means a type of take that should have the lowest priority, in real life gets the first water after a critical drought – before the environment and before humans.

The critical need for water in Macquarie Marshes after the worst drought in recorded history was ignored by NSW DPIE Water, who even ignored their own environmental water management team. See the Northern Basin First Flush Assessment Report

Supplementary access to several of the flows was allowed, removing about 35 Gigalitres before the Marshes. From the water that was metered upstream of the Marshes, a vast, unknown, unmetered volume of water was floodplain harvested.

Healthy Rivers Dubbo has put together some available information to conservatively estimate the volumes involved:

• From the Macquarie’s draft water resource plan, we know the the total on farm dam storage capacity in the valley is about 175 GL. Disregarding storage of off river schemes, and being very conservative, let’s say on farm dam storage close to the river that could catch water from the floodplain is about 70 to 90 GL.
• Water from drought breaking flows that started in February didn’t reach the northern most part of the Marshes until late April.
• When a third supplementary access event was announced in April, there was a relatively small amount of water extracted, indicating that the on-farm dams were already full of water.

It is likely that 70,000 to 90,000 megalitres of water was taken from the floodplain in the Macquarie from February to March 2020. For scale, Dubbo uses 8,000 megalitres a year from the river.

It was not until late April 2020 that flood water finally made it to the northern most part of the charred reed bed. Because the flows were delayed, the reeds in the northern most area missed the opportunity to get as much growth in as possible while the days were still warm, so they could store as much energy as possible before winter. We will see the impact of the delayed inundation on the recovery of the northern most section of the reed bed in spring.

Because of the delay in flows reaching all of the fire damaged reed bed, the requirement for environmental water in the Macquarie Marshes is still classified as HIGH as of autumn 2020. Connecting the Macquarie to the Barwon-Darling Rivers is a critical requirement for native fish and seasonal water replenishment in the Barwon. With flows reduced by unknown volumes, it will be more difficult to achieve the connection. To the untrained eye (or those with conflicting vested interests), this spring the Marshes look green and healthy – but without the early arrival of the flows, damaging weeds like lippia have taken hold. How much of the 4,000 ha burnt reed bed will come back? Yet to be seen.

It is difficult to overstate to the reader how frustrating it is that the volumes of floodplain harvested water taken this year in the Macquarie Valley are not public.

When asked in a drought update public forum on Thursday 28^th May 2020 what the volumes of floodplain harvesting take have been in the Macquarie Valley so far in 2020, WaterNSW stated they were under no obligation to tell the public. In the media, on twitter and facebook, when discussing floodplain harvesting take, representatives of the local irrigation industry play down the volume involved: “we only have a small number of floodplain harvesters in the Macquarie” Says Tony Quigley, Chair Macquarie River Food and Fibre on  ABC radio, NSW Country Hour 27/5/2020 

As this map shows, there are 99 properties and 180 storages being assessed for floodplain harvesting in the Macquarie.

Source: NSW Govt, Floodplain Harvesting Measurement Policy March 2020.

 Conclusion

Floods bring life. That is not merely a cheap platitude. Floods have, and continue to, form and feed our landscapes, rivers, wetlands, billabongs, aquifers, rich fertile floodplains, estuaries and oceans.

Since the 1990’s, the floods in the Basin have been taken. Massive volumes, entire flood events have been withheld and kept for free, to be used to create personal and corporate profit. The irrigation industry has had free access to unmeasured water from the floodplains for the past 30 years, at astounding cost to the environment, communities and economies downstream.

The injustice of this is situation is intolerable.

[1] Modelling variants of the Murray-Darling Basin Plan in the context of adverse conditions in the Basin, Glyn Wittwer March 2020.