tag:theconversation.com,2011:/id/topics/mass-fish-death-64947/articlesMass fish death – The Conversation2023-03-20T03:02:36Ztag:theconversation.com,2011:article/2021252023-03-20T03:02:36Z2023-03-20T03:02:36ZHow did millions of fish die gasping in the Darling – after three years of rain?<figure><img src="https://images.theconversation.com/files/516248/original/file-20230320-24-zym4lc.jpg?ixlib=rb-1.1.0&rect=4%2C0%2C1017%2C682&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Bill Ormonde</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Millions of dead fish float on the surface of the river. Native bony herring and introduced young carp, as well as a few mature Murray cod and golden perch. History is repeating on the Darling River at Menindee. This new fish kill is even worse than the enormous 2018–2019 fish kill. And it’s in almost the same location. </p>
<p>But how can so many fish die when we’ve been having floods? What’s killing them? </p>
<p>In both 2018 and 2023, the immediate answer is the same: the fish ran out of oxygen. Five years ago, it was because the river was almost dry. This time, it’s likely to be factors like the heatwave days earlier, receding floodwaters, bacteria pulling oxygen from the water – and no escape. </p>
<p>But two events like this in five years speaks to a deeper cause. The Darling River – known as the Baaka by Barkandji Traditional Owners – is very sick. Too much of its water is siphoned off for agriculture. Our native fish are hardy. They’re used to extremes. But this is too much, even for them. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1636583143745687552"}"></div></p>
<h2>Short term pressure, long term pain</h2>
<p>I was a member of the expert panel investigating the 2018–2019 Menindee fish kills. Everyone agreed the fish ran out of oxygen. It was a very dry period, and a cool front arriving after a heat wave mixed deep low-oxygen river water with the thin top layer which had oxygen. </p>
<p>But our panel also examined the long-term changes to the river. We found the long-term cause for the river’s decline was simple: too much water was being <a href="https://www.science.org.au/supporting-science/science-policy-and-sector-analysis/reports-and-publications/fish-kills-report">diverted upstream</a>. </p>
<p>It wasn’t just climate <a href="https://theconversation.com/excessive-water-extractions-not-climate-change-are-most-to-blame-for-the-darling-river-drying-192621">change</a> – it was irrigation. We warned it could <a href="https://theconversation.com/we-wrote-the-report-for-the-minister-on-fish-deaths-in-the-lower-darling-heres-why-it-could-happen-again-115063">happen again</a>. Now it has. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="dead fish darling river" src="https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516250/original/file-20230320-447-cr0ayg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Native bony bream died in their millions, as did young carp, golden perch and even Murray cod.</span>
<span class="attribution"><span class="source">Bill Ormonde</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>When faced with such environmental disaster, our leaders tend to reach for Dorothea MacKellar’s famous poem, My Country, and its line about a land “Of droughts and flooding rains.” Coalition water ministers at both federal and state level confidently blamed the drought for the first fish kill. Now, NSW premier Dominic Perrottet has linked <a href="https://www.abc.net.au/news/2023-03-18/nsw-menindee-mass-fish-kill-worst-in-region/102115184">this kill</a> to the recent floods. </p>
<p>This is part of the reason. But only part. When floodwaters engorged the Darling and its tributaries, it was a bonanza for bacteria that broke down dead wood lying on the floodplain. Unfortunately, this explosion of microorganisms had a devastating side effect: they sucked oxygen out of the water. </p>
<p>This is what’s known as a blackwater event (in reality, more greeny-brown). As the floodwaters moved downstream and the Darling’s flow decreased, millions of fish fled the floodplains and found themselves crammed back in the narrow river channel where they were hit by plummeting oxygen levels. </p>
<p>Desperate, the fish looked to escape. But upstream, their exit was blocked. In December, authorities had fully opened the gates to the Menindee main weir for the <a href="https://www.abc.net.au/news/2022-12-05/menindee-weir-opens-allowing-unimpeded-migration-for-native-fish/101732232">first time</a> in a decade to let fish migrate. But now the gates are shut. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="menindee weir" src="https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516254/original/file-20230320-18-yvz5st.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fish could swim up river past the Menindee main weir in December - but as flows slowed, the gates have been shut.</span>
<span class="attribution"><span class="source">Richard Kingsford</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>They couldn’t get into the main <a href="https://www.mdba.gov.au/water-management/infrastructure/menindee-lakes">Menindee Lakes</a>, where they might have found water with more oxygen, as they were blocked by the regulators – large taps used mainly to let water out. </p>
<p>Could they escape downstream? Perhaps some did. But for millions of fish, there was no time. Their bodies will only <a href="https://www.abc.net.au/news/2023-03-19/emergency-centre-activated-to-clean-up-menindee-fish-kill/102117524">make the problem worse</a>, as tonnes of rotting fish deposit vast quantities of nutrients into the river. That’s great for bacteria, algae and some fish-eating birds. But it’s not healthy for the river, its fish, or its people. </p>
<p>Yes, fish kills have always occurred but not at <a href="https://www.science.org.au/supporting-science/science-policy-and-sector-analysis/reports-and-publications/fish-kills-report">this scale</a>. The fundamental reason the fish of the Darling keep dying is because there is not enough water allowed to flow.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/fish-kills-and-undrinkable-water-heres-what-to-expect-for-the-murray-darling-this-summer-126940">Fish kills and undrinkable water: here's what to expect for the Murray Darling this summer</a>
</strong>
</em>
</p>
<hr>
<h2>Why is the Darling in such trouble?</h2>
<p>Since the 1980s, the Darling’s tributaries have steadily shrunk. The Macquarie, the Namoi, the Gwydir, the Border Rivers and the Condamine-Balonne are all shadows of the rivers they once were. </p>
<p>Much of their water is captured in large dams, such as Burrendong Dam, or intercepted by floodplain harvesting, which was legalised only last year by the NSW government to the dismay of environmentalists and <a href="https://www.abc.net.au/news/rural/2022-08-01/floodplain-harvesting-legislated-southern-nsw/101287572">farmers downstream</a>. </p>
<p>Just last week, before news of the fish kills at Menindee, water allocations announced by the NSW Government in the Namoi and Gwydir Rivers were at 113% and 275% respectively. While some of the water held in dams goes to the environment, much of the water in rural reservoirs is allocated for extraction – around 44% of the water held in the Gwydir Valley’s Copeton Dam, and 61% of the water in Keepit and Split Rock Dams in the Namoi Valley. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="river red gum on darling" src="https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516257/original/file-20230320-18-1vd4wc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">River red gums rely on periodic flooding. Without floodwaters, they can die.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The fish kills at Menindee are the clearest sign yet of how policy and management have failed the Darling. These catastrophes were inevitable. And the pain isn’t limited to fish. We are suffering too. </p>
<p>Taxpayers forked out nearly half a billion dollars <a href="https://www.abc.net.au/news/2019-02-26/wentworth-to-broken-hill-pipeline-turned-on/10844986">for a pipeline</a> from the Murray to Broken Hill, which nearly ran out of water in 2019. Why? Because the Darling was no longer dependable. In 2019, the towns of Wilcannia and Brewarrina <a href="https://www.thesaturdaypaper.com.au/news/rural/2019/03/09/wilcannia-the-town-with-no-water/15520500007800#hrd">ran out of water</a>, significantly affecting Aboriginal communities. Why? Because the Darling was so low. </p>
<p>Fish kills like this one make news for a few days, and then get forgotten. But unless we tackle the fundamental problem of a lack of water in our rivers, there will be many more to come. This is not a natural disaster. It is man-made. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/water-buybacks-are-back-on-the-table-in-the-murray-darling-basin-heres-a-refresher-on-how-they-work-200529">Water buybacks are back on the table in the Murray-Darling Basin. Here's a refresher on how they work</a>
</strong>
</em>
</p>
<hr>
<p><em>Correction: A previous version of this article said the water farmers and other users could take from the Namoi and Gwydir rivers was well beyond the total flows left in the rivers. In fact, the figures stated include carryover water allocations, and do not reflect the amount of water that can currently be extracted. The article has been amended to reflect this.</em></p><img src="https://counter.theconversation.com/content/202125/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Kingsford receives funding from the Australian Research Council, New South Wales, Queensland, Victorian and South Australian Governments, the Murray-Darling Basin Authority and a range of non-government organisations, including World Wide Fund for Nature, The Nature Conservancy and philanthropic sources. He is a member of the Wentworth Group of Concerned Scientists and a councillor on the Biodiversity Council. He is also part of the Next Generation Water Management Hub led by Charles Sturt University (funded through the Regional Research Collaboration Program of the Department of Education of the Australian Government), focusing on fish ecology and management. </span></em></p>For the second time in five years, millions of fish suffocated in the Darling River. This was not a natural disaster – it’s our doingRichard Kingsford, Professor, School of Biological, Earth and Environmental Sciences, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1221182019-08-26T04:51:42Z2019-08-26T04:51:42ZPaddling blind: why we urgently need a water audit<figure><img src="https://images.theconversation.com/files/289370/original/file-20190826-170941-18q8f4s.jpg?ixlib=rb-1.1.0&rect=31%2C52%2C1566%2C1144&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There's broad support from communities and farmers for proper water audits. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/shebalso/625453843/in/photolist-XgBCX-jaFipg-bDgyWR-beU5MP-aXDQZc-TaRygB-7iSLUY-aXDVaK-mizx5F-ehyEtb-9243gz-gpeBLu-7sgZWW-2afn2De-HA1WQY-4f2Rwg-GnP3Z-akX1ma-98JmR5-akZNKY-gcHLj6-n1vRhX-ZaLRrm-7yXFdj-gcJEGT-dFyz9x-9f2Ldh-898fn-gcF2zW-A9Jtk-7Am1cD-7NhR4V-7Amoze-7RgFGD-p8x1fE-dw5Mn-a9B5BC-28AA2cn-7AmpnB-a1kNs6-aN4DkV-5UHhjj-AtHZqv-jsM59z-e4CASe-VJUoQn-5XKLGJ-AsBrq3-gcGVqX-AtKAsn">John/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>In the wake of a <a href="https://www.mdbrc.sa.gov.au/">damning royal commission</a> and an <a href="https://www.youtube.com/watch?v=s83UuhDxT_Y">ABC Four Corners investigation</a>, the federal government has created an <a href="https://www.abc.net.au/news/2019-08-01/inspector-general-to-oversee-murray-darling-basin-integrity/11371966">Inspector General for the Murray-Darling Basin</a>, to combat water theft, ensure water recovery and efficiency projects are delivered properly, and essentially make sure everyone is <a href="https://www.sbs.com.au/news/new-tough-cop-to-oversee-murray-darling-basin-plan">acting as they should</a>.</p>
<p>While this is a laudable aim, the Inspector General – currently former Australian Federal Police Commissioner Mike Keelty – cannot hope to do this job without knowing how much water is being used in the Basin, by whom it is used, and where. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/billions-spent-on-murray-darling-water-infrastructure-heres-the-result-119985">Billions spent on Murray-Darling water infrastructure: here's the result</a>
</strong>
</em>
</p>
<hr>
<p>This might seem like basic information, but the <a href="http://www.bom.gov.au/water/nwa/2018/mdb/index.shtml">Bureau of Meteorology</a>, the <a href="https://www.mdba.gov.au/sites/default/files/pubs/SDL-Reporting-Compliance-Framework-Summary-Nov-18.PDF">Murray-Darling Basin Authority</a> and <a href="https://www.industry.nsw.gov.au/water/allocations-availability/water-accounting/gpw">state water accounts</a> are not up to the task.</p>
<p>We urgently need a comprehensive audit to track the water in the Murray Darling Basin, so Inspector General Keelty can effectively investigate what he has already described as a “<a href="https://www.thesaturdaypaper.com.au/news/politics/2019/04/27/keelty-warns-river-ripe-corruption/15562872008055">river ripe for corruption</a>”. </p>
<h2>Up the creek</h2>
<p>Back in 2004 all governments in Australia agreed to <a href="https://www.pc.gov.au/inquiries/completed/water-reform/national-water-initiative-agreement-2004.pdf">track and provide</a> information on water in terms of planning, monitoring, trading, environmental management, and on-farm management.</p>
<p>But water accounts still lack <a href="http://www.myoung.net.au/water/droplets.php">many essential features</a> including double-entry accounting. When applied to water, double-entry accounts means that when one person consumes more water, someone else must consume less. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/aboriginal-voices-are-missing-from-the-murray-darling-basin-crisis-110769">Aboriginal voices are missing from the Murray-Darling Basin crisis</a>
</strong>
</em>
</p>
<hr>
<p>The technology to track this already exists: satellites that can quantify surface water are successfully being used <a href="https://idwr.idaho.gov/GIS/mapping-evapotranspiration/">used in the United States</a>. </p>
<p>If we had <a href="http://farminstitute.org.au/publications-1/farm-policy-journals/2019-winter-a-thirst-for-certainty-irrigation-in-the-murray-darling-basin/fpj1602c-grafton-rq-williams-j-2019-thirst-for-certainty-the-urgent-need-for-a-water-audit-of-the-mu">monthly water consumption measurements</a>, we could see how much water is being used, by whom, when and where. This would help decision makers see problems before they emerge, such as the <a href="https://www.science.org.au/files/userfiles/support/reports-and-plans/2019/academy-science-report-mass-fish-kills-digital.pdf">mass fish deaths in the Darling River</a>, and respond in real time. </p>
<p>As a recent report from the <a href="https://www.edonsw.org.au/water_sharing_plan_barwon_darling_alluvial">Natural Resources Commission</a> shows, without proper accounting, too much water is taken upstream – seriously harming downstream communities.</p>
<h2>Wide support for an audit</h2>
<p>An independent Basin-wide water audit is supported by communities and some <a href="https://www.thesaturdaypaper.com.au/news/politics/2019/07/13/murray-darling-recovery-peril/15629400008434">irrigators</a>. </p>
<p>In July <a href="https://www.abc.net.au/news/rural/2019-07-26/nsw-farmers-call-for-murray-darling-royal-commission/11347834">NSW farmers</a> voted in support of a federal royal commission into “the failings of the Murray Darling Basin Plan”. In our view, this vote shows many farmers support much greater transparency about how much water is being consumed, and by whom.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-darling-river-is-simply-not-supposed-to-dry-out-even-in-drought-109880">The Darling River is simply not supposed to dry out, even in drought</a>
</strong>
</em>
</p>
<hr>
<p>Double-entry water consumption accounts would help identify whether the billions of dollars planned in subsidies to increase irrigation efficiency will actually deliver value for money. But irrigation improvements only generate public benefits when more water is left or returns to flow in streams and rivers. Such flows are essential to healthy rivers and sustainable Basin communities.</p>
<p>Irrigators’ crops benefit from increased efficiency, so subsidies <a href="https://www.pc.gov.au/inquiries/completed/basin-plan/report">help farmers greatly</a> – but it is very unclear whether they do anything for the public good. In fact, they seem to reduce the amount of water that finds its way back into the rivers. Research also shows infrastructure subsidies to improve irrigation efficiency <a href="https://science.sciencemag.org/content/361/6404/748">typically increases water consumption</a> at the Basin level. </p>
<p>Our research, <a href="https://www.tandfonline.com/doi/full/10.1080/13241583.2019.1579965">published earlier this year in the Australasian Journal of Water Resources</a> shows federal irrigation infrastructure subsidies may have reduced net stream and river levels. This is even after accounting for the water entitlements irrigators provided to the government in exchange for these subsidies.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-ways-the-government-can-clean-up-the-murray-darling-basin-plan-116265">5 ways the government can clean up the Murray-Darling Basin Plan</a>
</strong>
</em>
</p>
<hr>
<h2>Independent audits</h2>
<p>Just like financial accounts, water accounts must be <a href="https://asic.gov.au/regulatory-resources/financial-reporting-and-audit/auditors/auditor-independence-and-audit-quality/">independently audited</a>. </p>
<p>For the average taxpayer, who has to justify every dollar they get from the government, it’s hard to imagine how some corporations can be given millions of dollars in subsidies without actual measurements (before and after) of the claimed <a href="https://www.youtube.com/watch?v=s83UuhDxT_Y">water savings</a>. </p>
<p>If Newstart recipients need to <a href="https://www.humanservices.gov.au/individuals/services/centrelink/newstart-allowance/how-report-and-manage-your-payment">report and manage their income and have a job plan</a>, as part of a system of appropriate checks and balances, shouldn’t the Australian government also be checking whether billions spent on subsidies for irrigators actually saves water?</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-murray-darling-basin-scandal-economists-have-seen-it-coming-for-decades-119989">The Murray-Darling Basin scandal: economists have seen it coming for decades</a>
</strong>
</em>
</p>
<hr>
<p>A water audit <a href="https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Environment_and_Communications/MDBCommission2019/Submissions">would cost less than 1% of the money already spent</a> on water infrastructure subsidies in the Basin. Unlike irrigation infrastructure subsidies, a water audit is value for money. </p>
<p>Importantly, independent water consumption accounts would allow the Inspector General for the Murray-Darling Basin to effectively manage our most critical nature resource, water.</p><img src="https://counter.theconversation.com/content/122118/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Quentin Grafton is a signatory of the Murray-Darling Declaration. He received funding from the Murray-Darling Basin Authority in 2010.</span></em></p><p class="fine-print"><em><span>John Williams does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>How can Australia’s new Inspector General be expected to inspect waterways without a firm grasp of how much water in in them?Quentin Grafton, Director of the Centre for Water Economics, Environment and Policy, Crawford School of Public Policy, Australian National UniversityJohn Williams, Adjunct Professor Environment and Natural Resources, Crawford School of Public Policy, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1211002019-07-29T07:00:50Z2019-07-29T07:00:50ZNSW’s water plan is ‘not working’ but we can save the Barwon-Darling<p>The plan to manage water in the Barwon-Darling is not working, according to a <a href="https://www.nrc.nsw.gov.au/announcements/news-bddraftreport">draft review</a> released last week. </p>
<p>The New South Wales Natural Resources Commission, which released the draft report, found the Barwon-Darling is an “ecosystem in crisis”. The report provides a robust blueprint for a more sustainable water-sharing plan. </p>
<p>The review confirms criticism the existing plan gives too much water to irrigators and has added to pressures on the entire Murray-Darling ecosystem.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/5-ways-the-government-can-clean-up-the-murray-darling-basin-plan-116265">5 ways the government can clean up the Murray-Darling Basin Plan</a>
</strong>
</em>
</p>
<hr>
<h2>What the plan covers</h2>
<p>The draft review examines the <a href="https://legislation.nsw.gov.au/#/view/regulation/2012/488">2012 Water Sharing Plan for the Barwon-Darling</a>, which covers 1,600km of the river from Mungindi to Wilcannia. The river here flows south-west through a relatively narrow floodplain with a tightly meandering channel and a highly variable flow pattern. </p>
<p>The river is unregulated and depends heavily on upstream rivers for its water (for example, Condamine–Balonne, Border rivers, Gwydir and Namoi).</p>
<p>January’s <a href="https://theconversation.com/we-wrote-the-report-for-the-minister-on-fish-deaths-in-the-lower-darling-heres-why-it-could-happen-again-115063">massive fish kills</a> around Menindee are only the most recent example of the pressures on the river’s ecosystems. Alongside the fish deaths, research has shown that other aquatic species in the system, such as river mussels, have suffered losses that will take many decades to recover. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-wrote-the-report-for-the-minister-on-fish-deaths-in-the-lower-darling-heres-why-it-could-happen-again-115063">We wrote the report for the minister on fish deaths in the lower Darling – here's why it could happen again</a>
</strong>
</em>
</p>
<hr>
<p>Communities that live along the river told the commission people can no longer fish, swim or drink the river water. Graziers struggle to provide water for their stock because the river dries up more often.</p>
<p>Indigenous communities are particularly affected because without water their strong connection to the river – the Barka – is being damaged. A Barkandji elder told the commission:</p>
<blockquote>
<p>The river is everything. It’s my life, my culture. You take the water away from us, we’ve got nothing.</p>
</blockquote>
<h2>Bad priorities</h2>
<p>While the review found drought, upstream water extraction in NSW and Queensland and climate change have all contributed to these problems, the greatest effect comes from inappropriate water-sharing rules, particularly when water levels are low.</p>
<p>The law <a href="https://legislation.nsw.gov.au/#/view/act/2000/92">underpinning river management</a> in NSW prioritises protecting the environment and basic landholder rights (including native title) over irrigation. However, the commission found the current plan does not achieve this. </p>
<p>In fact, the plan has been highly controversial since it was enacted in 2012. This in large parts arose because major changes were made between the draft plan circulated in 2011 and the actual plan gazetted in 2012. The commission documents 16 such changes in the review and rates six as substantial. </p>
<p>The NSW government did not publicly explain the reason for such significant alteration in 2012, but there has been much speculation powerful vested interests influenced the government to provide more water for irrigation.</p>
<p>The most important effect of these changes was letting irrigators take water even when the river is very low. The review concludes:</p>
<blockquote>
<p>These provisions benefit the economic interests of a few upstream users over the ecological and social needs of the many.</p>
</blockquote>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-darling-river-is-simply-not-supposed-to-dry-out-even-in-drought-109880">The Darling River is simply not supposed to dry out, even in drought</a>
</strong>
</em>
</p>
<hr>
<h2>What to do?</h2>
<p>The review recommends the NSW government urgently change water-sharing rules so these better comply with the legal requirements to protect the environment and other water users, restore community trust and make the river more resilient to future shocks. </p>
<p>Key priorities for the NSW government are:</p>
<ul>
<li><p>redesigning the water-sharing rules so environmental protection and basic landholder rights cannot be harmed by lesser priorities such as irrigation</p></li>
<li><p>introduce new flow targets to more effectively protect critical ecosystems and enhance river health</p></li>
<li><p>change rules relating to water extractions by A Class licence holders during critical low-flow periods, particularly those relating to commence-to-pump, cease-to-pump, and the size of pumps.</p></li>
<li><p>introduce and enforce more effective metering and monitoring</p></li>
<li><p>develop strategies and rules that address the inevitable impacts of climate change</p></li>
<li><p>develop and implement more integrated management of water resources in the northern Murray-Darling Basin.</p></li>
</ul>
<p>The commission did note there have been positive changes to the NSW government’s approach to water policy and management since the ABC 4 Corners report <a href="https://www.abc.net.au/4corners/pumped/8727826">Pumped</a> in 2017 and the subsequent <a href="https://www.industry.nsw.gov.au/about/our-business/independent-review-water-management-and-compliance">Ken Matthews report</a>.</p>
<p>However, the Murray-Darling Basin Plan required NSW to complete a new water resource plan for the Barwon-Darling River by June 2019. The state missed this deadline. The NSW water minister has requested an extension to December 31 2019. A <a href="https://www.mdba.gov.au/sites/default/files/pubs/water-resource-plan-quarterly-report-june-2019_1.pdf">recent assessment by the Murray-Darling Basin Authority</a> suggests NSW is still some way from completing this water resource plan.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/drought-and-climate-change-are-driving-high-water-prices-in-the-murray-darling-basin-119993">Drought and climate change are driving high water prices in the Murray-Darling Basin</a>
</strong>
</em>
</p>
<hr>
<p>While NSW delays, the Barwon-Darling river system and its communities suffer. The NSW government now has an excellent blueprint for a new plan. It must urgently implement the review’s 29 recommendations and complete a new plan for the Barwon-Darling before the end of 2019.</p><img src="https://counter.theconversation.com/content/121100/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Barry Hart does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Irrigators get too much water from the Barwon-Darling even when river levels are critically low, according to a NSW government review.Barry Hart, Emeritus Professor Water Science, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1150632019-04-09T20:03:44Z2019-04-09T20:03:44ZWe wrote the report for the minister on fish deaths in the lower Darling – here’s why it could happen again<p>Over the recent summer, three significant fish death events occurred in the lower Darling River near Menindee, New South Wales. Species involved included Murray Cod, Silver Perch, Golden Perch and Bony Herring, with deaths estimated to be in the range of hundreds of thousands to over a million fish. These events were a serious ecological shock to the lower Darling region.</p>
<p>Our report for the Minister for Agriculture and Water Resources examines the causes of these events and recommend actions to mitigate the potential for repeat events in the future.</p>
<p>The <a href="https://www.mdba.gov.au/managing-water/drought-murray-darling-basin/fish-deaths-lower-darling/independent-assessment-fish">final report</a> has just been released, summarising what we found and what we recommend.</p>
<h2>Causes of the fish deaths</h2>
<p>High-flow events in the Darling River in 2012 and 2016 filled the Menindee Lakes and offered opportunities for substantial fish breeding, further aided by the targeted use of <a href="https://www.environment.gov.au/water/cewo">environmental water</a>.</p>
<p>The result was very large numbers of fish in the lakes, river channels and weir pools around Menindee. After the lake-filling rains of late 2016, two very dry years ensued, resulting in very low inflows into the Barwon-Darling river.</p>
<p>As the supply of water dried up, the river became a series of disconnected and shrinking pools. As the extremely hot and dry conditions in late 2018 took hold, the large population of fish around Menindee became concentrated within weir pools.</p>
<p><a href="http://www.bom.gov.au/climate/current/statements/scs66.pdf">Hot weather, low rainfall and low flows</a> provided ideal conditions for <a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">algal blooms</a> and <a href="https://iisd.org/ela/blog/commentary/lakes-stratify-turn-explain-science-behind-phenomena/">thermal stratification</a> in the weir pools, resulting in very low oxygen concentrations within the bottom waters.</p>
<p>With the large fish population now isolated to the oxygenated surface waters of the pools, all that was needed for the fatal blow was a trigger for the water profile to mix. Such a trigger arrived on three separate occasions, with changes in the weather that brought sudden drops in temperature and increased wind that caused sudden turnover of the low-oxygen bottom waters.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=320&fit=crop&dpr=1 600w, https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=320&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=320&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=402&fit=crop&dpr=1 754w, https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=402&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/268027/original/file-20190408-2935-1sk4g7q.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=402&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Summary of the multiple causes of the 2018-19 fish death events in the lower Darling river.</span>
</figcaption>
</figure>
<p>With the fish already stressed by high temperatures, they were now unable to gain enough oxygen from the water to breathe, and a very large number of them died. As we write, the situation in the lower Darling remains dire, and there is a risk of further fish deaths if there are no significant inflows to the river.</p>
<p>Fish deaths caused by these sorts of turnover events are <a href="https://www.monitor2manage.com.au/userdata/downloads/p_/nsw-fishkill.pdf">not uncommon</a>, but the conditions outlined above made these events unusually dramatic.</p>
<p>So, how did such adverse conditions arise in the lower Darling river and how might we avoid their reoccurrence? We’ve examined four influencing factors: climate, water management, lake operations, and fish mobility.</p>
<h2>Key influencing factors</h2>
<p>We found that the fish death events in the lower Darling were preceded and affected by <a href="http://www.bom.gov.au/climate/current/statements/scs68.pdf">exceptional climatic conditions</a>.</p>
<p>Inflows to the water storages in the northern Basin over 2017-18 were the second lowest for any two-year period on record. Most of the Murray-Darling Basin experienced its hottest summer on record, exemplified by the town of Bourke breaking a new heatwave record for NSW, with 21 consecutive days with a maximum temperature above 40°C.</p>
<p>We concluded that climate change amplified these conditions and will likely result in more severe droughts in the future.</p>
<p><a href="https://www.industry.nsw.gov.au/__data/assets/pdf_file/0004/162895/barwon-darling-water-sharing-plan-idel-and-take-limits-fact-sheet.pdf">Changes in the water access arrangements</a> in the Barwon–Darling River, made just prior to the commencement of the <a href="https://www.legislation.gov.au/Details/F2017C00078">Basin Plan</a> in 2012, exacerbated the effects of the drought. These changes enhanced the ability of irrigators to access water during low flow periods, meaning fewer flow pulses make it down the river to periodically reconnect and replenish isolated waterholes that provide permanent refuge habitats for fish during drought.</p>
<p>We conclude that the Lake Menindee scheme had been operated according to established protocols, and was appropriately conservative given the emerging drought conditions. But low connectivity in the lower Darling resulted in poor water quality and restricted mobility for fish.</p>
<h2>Recommended policy and management actions</h2>
<p>Given the right mix of policy and management actions, Basin governments can significantly reduce the risks of further fish death events and promote the recovery of affected fish populations.</p>
<p><a href="https://theconversation.com/it-will-take-decades-but-the-murray-darling-basin-plan-is-delivering-environmental-improvements-93568">The Basin Plan is delivering positive environmental outcomes</a> and more benefits will accrue once the plan is fully implemented. But more needs to be done to enhance river connectivity and protect low flows, first flushes and environmental flow releases in the Barwon-Darling river.</p>
<p>Drought resilience in the lower Darling can be enhanced by reconfiguring the Lake Menindee Water Savings Project, modifying the current Menindee Lakes operating rules and purchasing high security water entitlements from horticultural enterprises in the region.</p>
<p>In Australia, water entitlements are the rights to a share of the available water resource in any season. Irrigators get less (or no) water in dry (or extremely dry) years.</p>
<p>A high-security water entitlement is one with a high chance of receiving the full water allocation. In some systems, although not all, this is expected to happen 95 per cent of the time. And these high-security entitlements are the most valuable and sought after.</p>
<p>Fish mobility can be enhanced by removing barriers to movement and adding fish passageways. </p>
<p>It would be beneficial for environmental water holders to place more of their focus on sustaining fish populations through drought sequences.</p>
<p>The river models that governments use to plan water sharing need to be updated more regularly to accurately represent the state of Basin development, configured to run on a whole-of-basin basis, and improved to more faithfully represent low flow conditions.</p>
<p>There are large gaps in water quality monitoring, metering of water extractions and basic hydro-ecologic knowledge that should be filled. </p>
<p>Risk assessments need to be undertaken to identify likely fish death event hot spots and inform future emergency response plans.</p>
<p>All of these initiatives need to be complemented by more sophisticated and reliable assessments of the impacts of climate change on water security across the Basin.</p>
<h2>Governments must accelerate action</h2>
<p>Responding to the lower Darling fish deaths in a prompt and substantial manner provides governments an opportunity to redress some of the broader concerns around the management of the Basin.</p>
<p>To do so, Basin governments must increase their political, bureaucratic and budgetary support for high value reforms and programs, particularly in the northern Basin.</p>
<p>All of our recommendations can be implemented within the current macro-settings of the Basin Plan and do not require a revisiting of the challenging socio-political process required to define Sustainable Diversion Limits (SDLs).</p>
<p>Successful implementation will require a commitment to authentic collaboration between governments, traditional owners, local communities, and sustained input from the science community.</p>
<p><br></p>
<hr>
<p><em>The authors would like to acknowledge the contribution of Daren Barma, Director of Barma Water Consulting, to this article.</em></p>
<p><em>A version of this article has been published in <a href="https://pursuit.unimelb.edu.au/">Pursuit</a>.</em></p><img src="https://counter.theconversation.com/content/115063/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Vertessy is the Chair of the Murray Darling Basin Authority Advisory Committee on Social, Economic and Environmental Science. He received funding from the Murray Darling Basin Authority to chair this panel investigation.</span></em></p><p class="fine-print"><em><span>Fran Sheldon receives funding for research from the Australian Research Council and has at times undertaken paid contract work for the Murray Darling Basin Authority (MDBA) and the Commonwealth Environmental Water Holder (CEWH). She received funding from the MDBA to assist with activities associated with this panel investigation.</span></em></p><p class="fine-print"><em><span>Lee Baumgartner received funding from the Murray-Darling Basin Authority to assist with this panel investigation. He also receives funding from a range of government and private sources to undertake research in Australia and South East Asia. </span></em></p><p class="fine-print"><em><span>Nick Bond receives funding for research from a number of water management agencies including the Murray-Darling Basin Authority (MDBA), Department of Industry (Water) NSW, and the Commonwealth Environmental Water Office (CEWO). He received funding from MDBA to assist with this panel investigation, and is also a member of the MDBA's Advisory Committee on Social, Economic and Environmental Science.</span></em></p><p class="fine-print"><em><span>Simon Mitrovic received funding from the Murray-Darling Basin Authority to assist with this panel investigation. Simon Mitrovic receives funding from Department of Industry - Water and the Murray-Darling Basin Authority. </span></em></p>Fish deaths at the lower Darling can happen again. Here’s what we can do about it.Robert Vertessy, Enterprise Professor, The University of MelbourneFran Sheldon, Professor, Australian Rivers Institute, Griffith University, Griffith UniversityLee Baumgartner, Associate Research Professor (Fisheries and River Management), Institute for Land, Water, and Society, Charles Sturt UniversityNick Bond, Professor of Freshwater Ecology and Director of the Centre for Freshwater Ecosystems, La Trobe UniversitySimon Mitrovic, Associate Professor, University of Technology SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1101682019-01-21T04:42:24Z2019-01-21T04:42:24ZA good plan to help Darling River fish recover exists, so let’s get on with it<figure><img src="https://images.theconversation.com/files/254673/original/file-20190121-100279-1k26ycm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sheep grazing on the Darling River bed.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/d/367806149/">D./Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>The recent catastrophic collapse of Darling River fish communities is <a href="https://theconversation.com/the-darling-river-is-simply-not-supposed-to-dry-out-even-in-drought-109880">truly heartbreaking</a>. As fingers continue to be pointed in all directions, two questions bubble to the top of mind: can this system recover? And, if so, how?</p>
<p>From even the darkest hour comes hope. It was wonderful to hear the basin’s various governments speak about developing a “<a href="https://www.theguardian.com/australia-news/2019/jan/14/minister-warns-of-more-fish-deaths-this-week-as-temperatures-rise-in-nsws-west">strategy</a>” over recent weeks. And the good news is that one already <a href="http://www.finterest.com.au/">exists</a> and can guide our actions from here.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-darling-river-is-simply-not-supposed-to-dry-out-even-in-drought-109880">The Darling River is simply not supposed to dry out, even in drought</a>
</strong>
</em>
</p>
<hr>
<h2>The Native Fish Strategy</h2>
<p>The <a href="https://www.google.com/search?q=native+fish+strategy&oq=native+fish+strategy&aqs=chrome.0.0j69i61l2j0.2927j0j4&sourceid=chrome&ie=UTF-8">Native Fish Strategy</a> for the Murray-Darling Basin is a living document. It was developed in 2001 and lays out a plan for helping the basin’s fish communities recover from where they are now, <a href="https://www.mdba.gov.au/sites/default/files/pubs/MDBA-Fish-species-book.pdf">at 10% of pre-European levels (0% in some parts), back to 60% over 50 years</a>. </p>
<p>The strategy is one of the rare documents agreed to by the federal government and all basin states: because it made sense. It was visionary and forward-thinking – contributed to by a multitude of scientists, managers, Indigenous groups and basin communities.</p>
<p>During the first ten years of its life the strategy helped us learn more about our native fish than in any other period. But direct funding ceased in 2012. Since then, implementation of its recommendations has been opportunistic and without central coordination. That said, the strategy is still relevant and the need to resurrect its funding has never been greater.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
</strong>
</em>
</p>
<hr>
<p>The Native Fish Strategy recognised that native fish are recreationally and culturally valued by all those who live in, and visit, the Murray-Darling Basin. It also acknowledged that most native fish species found there aren’t found anywhere else in the world. </p>
<p>Most importantly, the strategy describes these fish as important indicators of ecosystem health. That should be a warning to us when considering recent events in the Darling. When fish are stressed, it is because our rivers are stressed. It’s that simple.</p>
<h2>How to help our fish</h2>
<p>Our native fish are pretty simple creatures, really. They need healthy habitat, more natural water flows, the ability to move around, minimal pests to compete with, and sparing use of active human intervention (including stocking). The first decade of the strategy sought to provide hard data on how a range of different threats impact fish. It also successfully trialled a suite of solutions.</p>
<p>Because of the strategy, we know why <a href="http://www.finterest.com.au/fish-habitats/making-fish-happen-by-integrating-habitat-flow-and-connectivity/">aquatic and riparian habitats are crucial for fish</a>. And putting habitat back in the river, through plans like building fish hotels (<a href="https://www.abc.net.au/news/2017-11-14/fish-hotels-provide-essential-habitat-lake-bonney-riverland-sa/9145550">yes, they are a thing</a>), can help fish recover rapidly. Many decades of clearing the Darling River of logs and minor obstructions has left large stretches smooth and unsuitable for fish to lay eggs, shelter or hide from predators, so reintroducing native plants and natural “<a href="https://www.mdba.gov.au/sites/default/files/pubs/Snags_Resnagging-FS.pd">snags</a>” is essential for a productive future fishery.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=369&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=369&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=369&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=463&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=463&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254676/original/file-20190121-100261-zsla8q.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=463&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">When logs and other natural debris fall into rivers they form ‘snags’, creating pockets of calm water where fish can hide, rest and lay eggs.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/spelio/3876743855/in/photolist-vR2RB-him5NF-8uKzr1-6UzjTi-7RzF95-4w2wdc-4w2vWe-4w2wXx-4w6DFE-6W7jQn">spelio/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>The current drought, the second in ten years, has added to the need for better water flow regulation. Not to belabour the obvious, but fish need water. Some parts of the Darling main channel have been dry for some time. No water means no fish.</p>
<p>Many wetlands in the Lower Darling have not been watered for more than a decade. For some fish in the Murray-Darling, that is one-third of their life; for others it is longer than their lifetime. Native Fish Strategy research taught us that with the <a href="http://www.finterest.com.au/natives-and-introduced/e-water-success-tales-in-the-basin/">right amount of water, fish will spawn and thrive</a>, but it is important that the water is of high quality, is flowing, and connects fish with their crucial habitat.</p>
<h2>Finding the balance</h2>
<p>Fish scientists and managers are realists and recognise that there will always be competing uses for water – including irrigation and town supply. But the fact that our fish stocks are so stressed highlights the need to find a balance. </p>
<p>Many people don’t realise that when water is taken for irrigation or drinking, <a href="https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0006/137436/output-633-617.pdf">fish are inevitably taken with it</a>.</p>
<p>Work under the Native Fish Strategy demonstrated that anywhere between <a href="http://www.finterest.com.au/natives-and-introduced/diversion-screening/">100 and 12,000</a> fish can be abstracted, per day, by a single pump. When extrapolated over the many thousand irrigation pumps and diversion points across the basin, this means millions of fish are lost each year. They are either diverted into water distribution canals, or pumped onto crops and die.</p>
<p>This can be fixed by fitting pumps with off-the-shelf or custom-designed <a href="https://www.awmawatercontrol.com.au/projects/gunbower-fish-exclusion-screen-project-cohuna/">fish screens</a>. Each pump that can be fitted with a screen in the Darling will translate to thousands of fish that will stay in the river. When conditions are right again, screening pumps will be a key to helping fish recover. Presently, no pumps on the Darling are fitted with screens for <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1442-8903.2012.00655.x">fish protection</a>.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-is-oxygen-sucked-out-of-our-waterways-109795">How is oxygen 'sucked out' of our waterways?</a>
</strong>
</em>
</p>
<hr>
<p>We also know the Darling River is an important <a href="http://www.swimway.org/">fish swimway</a>. There is a famous story among fish scientists of a tagged golden perch which, during 1974 flooding, migrated from Berri in South Australia to the Condamine River in Queensland. It is a stark demonstration that fish in the basin ignore political boundaries. But in non-flood years such a migration is impossible; there are far too many barriers such as weirs and dams.</p>
<p>There is strong evidence that in some years the Lower Darling contributes significantly to fish populations in <a href="http://www.pir.sa.gov.au/__data/assets/pdf_file/0019/248131/Golden_Perch_Murray_Darling_Basin_Report_-_FINAL_.pdf">Victoria and South Australia</a>. </p>
<p>This connectivity is of paramount importance for affected reaches of the Darling. For these reaches to recover, fish need to migrate from elsewhere. The Native Fish Strategy taught us that providing fishways (also known as fish ladders) and <a href="https://www.awmawatercontrol.com.au/products/layflat/">fish-friendly regulators with layflat gates</a> helps larvae drift downstream, improving recovery. There is already a <a href="https://www.dpi.nsw.gov.au/fishing/habitat/publications/pubs/fishway-options-for-weirs-in-the-northern-murray-darling-basin">blueprint available to connect the Darling</a>: it only needs to be implemented.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=406&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=406&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=406&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=510&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=510&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254674/original/file-20190121-100292-1o9emhi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=510&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This schematic shows fish ladders already installed in some parts of the River Murray to let fish swim by man-made barriers.</span>
<span class="attribution"><span class="source">AAP Image/South Australian Government</span></span>
</figcaption>
</figure>
<h2>What does the Darling’s future look like?</h2>
<p>The Native Fish Strategy has provided us with a range of tools to help the Darling River quickly recover. So the future of the Darling depends on what we do now. It is up to us to ensure we leave future generations a river in better condition than it is in now. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-time-to-restore-public-trust-in-the-governing-of-the-murray-darling-basin-109797">It's time to restore public trust in the governing of the Murray Darling Basin</a>
</strong>
</em>
</p>
<hr>
<p>This is our Waterloo moment. The scoping work has been done; the strategy already exists; the solutions have already been developed and tested. But all of this is meaningless if it’s not used. The Darling River has sent us a strong message. The question is: will we listen? We bloody well need to.</p><img src="https://counter.theconversation.com/content/110168/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lee Baumgartner manages a suite of research projects that receive funding from various Australian government departments, the Ian Potter Foundation and National Geographic Society.</span></em></p><p class="fine-print"><em><span>Max Finlayson has over many years received funding from Australian Governments to undertake river and wetland research, and to provide advice on technical issues and policy implications, including for water pollution and climate change. He was for 25 years a member of the Scientific and Technical Review Panel of the Ramsar Convention on Wetlands, in different capacities and with three different employers, and is President-elect of the international Society of Wetland Scientists. </span></em></p>A decade of bipartisan research has provided plenty of answers to the problems plaguing the Darling River.Lee Baumgartner, Associate Research Professor (Fisheries and River Management), Institute for Land, Water, and Society, Charles Sturt UniversityMax Finlayson, Director, Institute for Land, Water and Society, Charles Sturt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1099532019-01-16T19:10:13Z2019-01-16T19:10:13ZCotton and rice have an important place in the Murray Darling Basin<p>The widespread deaths of <a href="https://theconversation.com/the-darling-river-is-simply-not-supposed-to-dry-out-even-in-drought-109880">fish in the Darling River</a> – with more predicted to come – has raised serious questions about the allocation of water between agriculture and the environment. Water-hungry crops like cotton and rice are also raising eyebrows: are they worth growing in the Murray Darling Basin?</p>
<p>The situation is a little more complicated than it may appear. Cotton and rice need plenty of water, but they might actually be some of the best crops to help cope with a rapidly changing climate. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-darling-river-is-simply-not-supposed-to-dry-out-even-in-drought-109880">The Darling River is simply not supposed to dry out, even in drought</a>
</strong>
</em>
</p>
<hr>
<h2>Flexible crops are vital</h2>
<p>It’s true cotton and rice are both “<a href="https://cottonaustralia.com.au/cotton-library/fact-sheets/cotton-fact-file-water">thirsty</a>” crops. Cotton requires about 7.8 million litres per hectare to grow, while rice needs roughly 12.6 million litres per hectare.</p>
<p>More importantly however, they are both annual crops. Farmers plant, grow and harvest in the same 12 month period. This means they can look to the year ahead and decide how much to plant given water availability and seasonal rainfall predictions. </p>
<p>Along the Murray and Darling rivers, which are some of the <a href="https://doi.org/10.1016/j.jhydrol.2007.09.002">most variable in the world</a>, the flexibility to plant more or less in a given year is very valuable. In a drought year with limited water like this one, a rice or cotton farmer may even chose to plant nothing and simply sell their remaining water allocation to another farmer.</p>
<p>During a flood year they can move into full production and grow bumper crops. For an annual crop like this, farmers may only need three good years out of five to have a viable business. </p>
<p>In contrast, perennial crops like orchards or vineyards need a very secure water supply, every year without fail. The trees and vines take years to mature, so a bad drought can be devastating: if they die, a farm could be set back a decade waiting for them to regrow.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-is-oxygen-sucked-out-of-our-waterways-109795">How is oxygen 'sucked out' of our waterways?</a>
</strong>
</em>
</p>
<hr>
<p>The Murray Darling Basin is an <a href="http://dx.doi.org/10.1007/s13280-014-0495-x">epicentre</a> for the impact of climate change, in terms of water availability. It’s vital we have crops like rice and cotton that can produce in a good year. Then, with relatively minor consequences, <em>not</em> produce in a dry year when it would be better to have the remaining water going to the environment and higher value agricultural crops like citrus, stone fruit and grapes. Our rural communities need to produce a diverse range of agricultural commodities and industries to be more resilient and thrive.</p>
<h2>Do we have the balance right?</h2>
<p>While I think we need the cotton and rice industries, this doesn’t mean that we’re distributing water well. The disastrous <a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">algal blooms</a> choking the Darling River show clearly taking too much water out of the Murray Darling Basin severely damages freshwater ecosystems during droughts. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
</strong>
</em>
</p>
<hr>
<p>The sort of tragedy we’re seeing on the Darling River is because too little water has been allocated to the environment. </p>
<p>We need to reallocate water from irrigated agriculture to improve the health of the environment, support people living along the rivers, and other rural industries that depend on healthy rivers, like grazing, recreational fishing and tourism. </p>
<p>This is, I believe, in large part a value judgement. If we, as a society, are going to take water from the rivers, we have to decide how much of the environment to allow to die off in that process. This is how we support irrigated agriculture and associated communities. The fish deaths on the Darling River are a clear sign we have not got that balance right. </p>
<h2>The ‘water stock market’ generally works</h2>
<p>The trade in water allocations – between, for example, rice and cotton growers to a perennial crop producer – is a key <a href="http://dx.doi.org/10.1016/j.agwat.2013.12.001">drought adaptation measure</a> in the Murray Darling Basin. It will only become more important with climate change, which is predicted to make droughts <a href="https://theconversation.com/recent-australian-droughts-may-be-the-worst-in-800-years-94292">more frequent and intense</a>. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/recent-australian-droughts-may-be-the-worst-in-800-years-94292">Recent Australian droughts may be the worst in 800 years</a>
</strong>
</em>
</p>
<hr>
<p>In a drought year, we need a grape grower who’s short of water to be able to quickly buy extra water from a farmer who might produce a lower-value crop. This keeps the vineyard alive, able to keep employing the people picking the grapes, and keeping their wine production facility going.</p>
<p>This is critical for rural communities in drought for maintaining employment and small businesses who supply services from nearby towns. Therefore, we need a modest share of annual crop growers like rice and cotton growers in the system to keep our broader communities healthy. </p>
<p>While some irrigators appear to have <a href="https://www.abc.net.au/4corners/pumped/8727826">broken the rules</a> and taken water they were not entitled to, this is also a <a href="https://theconversation.com/its-time-to-restore-public-trust-in-the-governing-of-the-murray-darling-basin-109797">crisis of management</a>. Our state governments, in particular, have <a href="http://wentworthgroup.org/2018/05/submission-to-sa-royal-commission/2018/">failed to adequately fulfil their duties</a> to the environment and the Australian public as stewards of our rivers. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-time-to-restore-public-trust-in-the-governing-of-the-murray-darling-basin-109797">It's time to restore public trust in the governing of the Murray Darling Basin</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/109953/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jamie Pittock is a member of the Wentworth Group of Concerned Scientists and is a scientific adviser to WWF Australia.</span></em></p>Crises in the Darling River have raised questions about cotton and rice farming in the Murray Darling Basin.Jamie Pittock, Professor, Fenner School of Environment & Society, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1098802019-01-15T19:13:34Z2019-01-15T19:13:34ZThe Darling River is simply not supposed to dry out, even in drought<figure><img src="https://images.theconversation.com/files/253808/original/file-20190115-180516-1t15oz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Puddles in the bed of the Darling River are a sign of an ecosystem in crisis.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/62459458@N08/27243660252">Jeremy Buckingham/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The <a href="https://www.mdba.gov.au/managing-water/drought-murray-darling-basin/fish-deaths-lower-darling">deaths of a million or more fish</a> in the lower Darling River system over the past few weeks should come as no surprise. Quite apart from specific warnings given to the NSW government <a href="https://www.smh.com.au/national/nsw-ignored-warnings-on-threat-of-fish-kills-20190113-p50r4v.html">by their own specialists</a> in 2013, scientists have been warning of devastation <a href="https://www.sciencedirect.com/science/article/pii/S0022169499001912">since the 1990s</a>. </p>
<p>Put simply, ecological evidence shows the Barwon-Darling River is not meant to dry out to disconnected pools – even during drought conditions. Water diversions have disrupted the natural balance of wetlands that support massive ecosystems. </p>
<p>Unless we allow flows to resume, we’re in danger of seeing one of the worst environmental catastrophes in Australia. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
</strong>
</em>
</p>
<hr>
<h2>Dryland river</h2>
<p>The Barwon-Darling River is a “dryland river”, which means it is <a href="http://www.publish.csiro.au/MF/MF94161">naturally prone</a> to periods of extensive low flow punctuated by periods of flooding. </p>
<p>However, the presence of certain iconic river animals within its channels tell us that a dry river bed is not normal for this system. The murray cod, dead versions of which have recently bought graziers to tears and politicians to retch, are the sentinels of permanent deep waterholes and river channels – you just <a href="https://www.mdba.gov.au/sites/default/files/archived/mdbc-NFS-reports/2202_factsheet_native_murray_cod.pdf">don’t find them</a> in rivers that dry out regularly.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/bjJXKE8ws_c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Less conspicuous is the large river mussel, <a href="https://bie.ala.org.au/species/urn:lsid:biodiversity.org.au:afd.taxon:2c316d50-67ff-46e7-a98e-e988bbaa1312"><em>Alathyria jacksoni</em></a>, an inhabitant of this system for thousands of years. Its shells are abundant in Aboriginal middens along the banks. These invertebrates are unable to tolerate low flows and low oxygen, and while dead fish will float (for a while), shoals of river mussels are probably dead on the river bed. </p>
<p>This extensive drying event will cause regional extinction of a whole raft of riverine species and impact others, such as the <a href="https://www.abc.net.au/news/2018-02-25/get-to-know-the-rakali-australias-native-water-rat/9464212">rakali</a>. We are witnessing an ecosystem in collapse.</p>
<h2>Catastrophic drying</h2>
<p>We can see the effects of permanent drying around the world. The most famous example is the drying of the Aral Sea in Central Asia. Once the world’s fourth largest inland lake, it was reduced to <a href="http://science.sciencemag.org/content/241/4870/1170">less than 10% of its original volume</a> after years of water extraction for irrigation. </p>
<p>The visual results of this exploitation still shock: images of large fishing boats stranded in a sea of sand, abandoned fishing villages, and a vastly changed microclimate for the regions surrounding the now-dry seabed. Its draining has been <a href="https://theconversation.com/worlds-worst-environmental-disaster-set-to-be-repeated-with-controversial-new-dam-in-africa-107070">described</a> as “the world’s worst environmental disaster”. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-drained-the-aral-sea-once-before-but-there-are-no-free-refills-this-time-round-32513">Humans drained the Aral Sea once before – but there are no free refills this time round</a>
</strong>
</em>
</p>
<hr>
<p>So, what does the Aral Sea and its major tributaries and the Darling River system with its tributary rivers have in common? Quite a lot, actually. They both have limited access to the outside world: the Aral Sea basin has no outflow to the sea, and while the Darling River system connects to the River Murray at times of high flow, most of its water is held within a vast network of wetlands and floodplain channels. Both are semi-arid. More worryingly, both have more the 50% of their average inflows extracted for irrigation.</p>
<p>There is one striking difference between them. The Aral Sea was a permanent inland lake and its disappearance was visually obvious. The wetlands and floodplains of the Barwon-Darling are mostly ephemeral, and the extent of their drying is therefore hard to visualise.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-time-to-restore-public-trust-in-the-governing-of-the-murray-darling-basin-109797">It's time to restore public trust in the governing of the Murray Darling Basin</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253807/original/file-20190115-180500-17etik0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An orphaned ship in former Aral Sea, near Aral, Kazakhstan.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Aralship2.jpg">Wikipedia</a></span>
</figcaption>
</figure>
<p>All the main tributaries of the Darling River have floodplain wetland complexes in their lower reaches (such as the Gwydir Wetlands, Macquarie Marshes and Narran Lakes). When the rivers flow they absorb the water from upstream, filling before releasing water downstream to the next wetland complex; the wetlands acting like a <a href="http://www.publish.csiro.au/MF/MF10106">series of tipping buckets</a>. Regular river flows are essential for these sponge-like wetlands.</p>
<p>So, how has this hydrological harmony of regular flows and fill-and-spill wetlands changed? And how does this relate to the massive fish kills we are seeing in the lower Darling system? </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-is-oxygen-sucked-out-of-our-waterways-109795">How is oxygen 'sucked out' of our waterways?</a>
</strong>
</em>
</p>
<hr>
<p>While high flows will still make it through the Barwon-Darling, filling the floodplains and wetlands, and connecting to the River Murray, the low and medium flow events have disappeared. Instead, these are captured in the upper sections of the basin in artificial water storages and used in irrigation. </p>
<p>This has essentially dried the wetlands and floodplains at the ends of the tributaries. Any water not diverted for irrigation is now absorbed by the continually parched upstream wetlands, leaving the lower reaches vulnerable when drought hits. </p>
<p>By continually keeping the Barwon-Darling in a state of low (or no) flow, with its natural wetlands dry, we have reduced its ability to cope with extended drought.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-a-wetland-might-not-be-wet-103687">Why a wetland might not be wet</a>
</strong>
</em>
</p>
<hr>
<p>While droughts are a natural part of this system and its river animals have adapted, they can’t adjust to continual high water caused in some areas by water diversions – and they certainly can’t survive long-term drying. </p>
<p>The Basin Plan has <a href="https://theconversation.com/it-will-take-decades-but-the-murray-darling-basin-plan-is-delivering-environmental-improvements-93568">come some way</a> in restoring some flows to the Barwon-Darling, but unless we find a way to restore more of the low and medium flows to this system we are likely witnessing Australia’s worst environmental disaster.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/it-will-take-decades-but-the-murray-darling-basin-plan-is-delivering-environmental-improvements-93568">It will take decades, but the Murray Darling Basin Plan is delivering environmental improvements</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/109880/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fran Sheldon receives funding from the Australian Research Council and has at times undertaken paid contract work for the Murray Darling Basin Authority and the Commonwealth Environmental Water Holder.</span></em></p>Mass fish deaths are a blaring warning sign for the heath of the Murray Darling Basin, but just as worrying is the sight of dry areas in the Darling.Fran Sheldon, Professor, Australian Rivers Institute, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1097972019-01-15T00:44:38Z2019-01-15T00:44:38ZIt’s time to restore public trust in the governing of the Murray Darling Basin<figure><img src="https://images.theconversation.com/files/253604/original/file-20190114-43535-1d0sshz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Going all the way back: rules for the Murray Darling Basin are in Australia's constitution. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/knitspirit/6720844065/in/photolist-beU5MP-8X9mR-gpetZD-898fn-898oW-6bto8Q-gcGfG5-gcGqAo-gcGVqX-gcJ7Xa-gcJEGT-bWuaqo-A9Jtk-2ckQ4H1-5wiQ27-TWN2k7-SHUNYy-Tqkj5Y-SHT5YJ-TWMgbW-TWJJos-TqjQrw-SLE8uc-TLp69S-TNQWQ2-TLrJro-TLteGf-TLtqEs-SHUqk7-SHSV3b-SHVSqb-SLEyXg-SHTaoA-SLEq4z-TqjPkd-TNNSve-25cXy5z-9fJfG-9fJsp-9fH4r-nKvb-9fJFp-9fJ7a-9fHDq-9fHuu-9fJmN-9fGUe-9g8AT-9fHeQ-9fHXF">KnitSpirit/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span></figcaption></figure><p>Fish deaths in the <a href="https://www.abc.net.au/news/2019-01-08/second-fish-kill-in-darling-river-at-menindee/10696632">Darling River</a> have once more raised the public profile of incessant political controversies about the Murray Darling Basin. These divisive debates reveal the deeply <a href="https://www.mdpi.com/2073-4441/10/2/113">contested nature of reforms to water policy in the Basin</a>.</p>
<p>It feels like Australia has been here before – algae blooms are not uncommon in these rivers. In 1992, the Darling suffered the <a href="https://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526">world’s largest toxic algal bloom</a>, over 1,000 kilometres long. This crisis became an iconic catalyst, and helped prompt the state and federal governments agreeing to <a href="https://www.mdpi.com/2073-4441/10/2/113">water reforms in 1994</a>.</p>
<p>Hopefully, our current crisis may be an opportunity to shine a strong light on the complexities of governing the Basin, and initiate the meaningful reforms needed to restore public trust.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-is-oxygen-sucked-out-of-our-waterways-109795">How is oxygen 'sucked out' of our waterways?</a>
</strong>
</em>
</p>
<hr>
<h2>Forewarned is forearmed</h2>
<p>The rivers of the basin are unique and precious. Australia needs high quality and independent science to understand them and guide their management. Unfortunately in 2012 state and federal governments cut three important programs that provided vital research on the Basin’s rivers: </p>
<ul>
<li>the <a href="https://www.publish.csiro.au/mf/mf09043">Sustainable Rivers Audit</a> (an independent scientific audit of river health) </li>
<li>a dedicated <a href="http://www.seaci.org">climate science program</a></li>
<li>the acclaimed <a href="https://onlinelibrary.wiley.com/toc/14428903/2014/15/s1">Native Fish Program</a>, which combined applied research with community engagement.<br></li>
</ul>
<p>So while yesterday’s announcement of A$5 million funding to a new <a href="https://www.theage.com.au/environment/sustainability/ecological-disaster-emergency-meeting-called-with-more-fish-deaths-imminent-20190113-p50r4u.html">native fish recovery program</a> is welcome, good science alone is not enough. Good policy processes and robust institutions are needed to apply this information. We cannot continue to <a href="https://www.smh.com.au/national/nsw-ignored-warnings-on-threat-of-fish-kills-20190113-p50r4v.html">ignore expert warnings</a>.</p>
<h2>A crisis of trust</h2>
<p>Since a 2017 Four Corners program exposed disturbing allegations of <a href="https://www.abc.net.au/4corners/pumped/8727826">water theft and corruption</a>, the media has revealed a host of further probity issues.</p>
<p>These and a plethora of formal inquiries into MDB governance indicates a crisis of trust, legitimacy and public confidence – in short, a <a href="http://www.tai.org.au/sites/default/files/P531%20The%20Basin%20files%20Vol%20I%20%20%5BWEB%5D.pdf">loss of authority</a>.</p>
<p>The <a href="https://www.aph.gov.au/Parliamentary_Business/Committees/Senate/Rural_and_Regional_Affairs_and_Transport/MurrayDarlingPlan/Report">2018 federal Senate inquiry</a> documents a litany of concerns, while disturbing evidence given at a <a href="http://www.mdbrc.sa.gov.au/sites/g/files/net3846/f/david_bell_final_witness_statement.pdf?v=1529025595,%202018.%20755%2047">South Australian Royal Commission</a> raised substantive doubts about failures to heed the best scientific advice in the development of the Basin Plan.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
</strong>
</em>
</p>
<hr>
<h2>More Commonwealth oversight is not enough</h2>
<p>Without doubt pressure is mounting for more reforms. The Senate’s Rural and Regional Affairs Committee and the <a href="https://www.pc.gov.au/inquiries/current/basin-plan/draft">Productivity Commission</a> have recommended splitting the Murray Darling Basin Authority into two entities – the MDB Corporation and a MDB Regulator – in order to clearly separate the Commonwealth’s regulatory oversight from other roles.</p>
<p>These proposals deserve critical scrutiny. Structural reorganisation can provide an illusion of government action, but can have long-term effects on the efficacy and justice of water governance.</p>
<p>The Murray Darling has a unique place in Australia’s history, environment, economy and culture. Agreements about its governance have their origins in debates leading up to Federation in 1901. Any renegotiation needs to respect the Constitution and the different legal powers of the states and the Commonwealth.</p>
<p>So reform to institutional arrangements need bespoke design. These are the legitimate remit of our discursive democracy. Nonetheless, the <a href="http://www.oecd.org/governance/oecd-principles-on-water-governance.htm">OECD’s 12 water governance principles</a> usefully provide guidance about the need for clarity of roles, transparency, effectiveness, efficiency and broad stakeholder engagement.</p>
<p>Current calls for reorganisation focus on clarifying the Commonwealth’s regulatory role, but this is fairly narrow. Reforms are needed at all scales. </p>
<p>The governance challenges in the MDB require modernisation and redesign of arrangements across regional, state and Commonwealth agencies. This includes structuring “constructive tensions” that ensure transparency and accountability. Just like the police don’t control the courts, we need to more clearly define and separate roles in the water sector.</p>
<h2>Embracing radical transparency</h2>
<p>We need all water agencies to adopt a formal charter of transparency and openness. All state and Commonwealth agencies should open their books to scrutiny, rather than hiding information behind claims of “commercial in confidence” or opaque “freedom of information” processes. </p>
<p>Greater transparency measures should also be a condition of all water licences. It’s entirely feasible to create <a href="https://theconversation.com/tax-returns-for-water-satellite-audited-statements-can-save-the-murray-darling-81833">modern monitoring regimes</a>, using state-of-the art digital metering coupled with annual water-use declarations. These would be similar to tax returns enforced with random audits and satellite verification of areas irrigated. If made publicly available, all interested parties could audit water extractions.</p>
<p>But doubts don’t exclusively focus on irrigators’ compliance. We also need to address the states and their willingness and capability to enforce regulations. Policies of radical transparency could be supported with openly available water data. With digital meters and automated gauging of river flows, we could create a computer platform where anybody could develop river models using real data, in near real-time.</p>
<p>Harnessing the power of citizen involvement, trust and openly sharing information has been a hallmark of <a href="https://theconversation.com/joan-kirner-united-farmers-and-conservationists-to-care-for-the-land-42746">Australia’s landcare</a> and natural resource management. This is where we should look for the <a href="https://blogs.crikey.com.au/rooted/2010/11/16/murray-murmurings-rethinking-the-basin-plan/">next generation</a> of governance in the Basin.</p>
<p>Open books means communities, industries, research and educational institutions can all help monitor our <a href="https://www.cogitatiopress.com/politicsandgovernance/article/view/1221">institutions</a> and ensure rivers are managed in the public’s interest.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/recent-australian-droughts-may-be-the-worst-in-800-years-94292">Recent Australian droughts may be the worst in 800 years</a>
</strong>
</em>
</p>
<hr>
<p>Finally, droughts should not come as surprise. They are a recurrent feature of the Basin. With climate change, <a href="http://www.seaci.org">more frequent and intense droughts</a> are predicted. As a nation we can do better than lurching from crisis to crisis each time drought returns.</p>
<p>We need careful deliberation about the institutions that will rebuild public confidence and restore trust in the governing of the Murray Darling. It’s time to develop a 21st century system that is cooperative, transparent and just.</p><img src="https://counter.theconversation.com/content/109797/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jason Alexandra operates a small independent research and consulting business, Alexandra and Associates, that has at times undertaken paid contract work for the Murray Darling Basin Authority and other government agencies involved in water and rivers. He is also an irrigator in Southern Victoria - not in the Murray Darling.
He was a former executive at the MDBA between 2008 and 2013 with wide ranging responsibilities including for native fish and assessing riverine health. He received no funding for the preparation of this article and has no conflicts of interest.</span></em></p>Public confidence in the institutions in charge of the Murray Darling Basin has plummeted – with good reason.Jason Alexandra, PhD candidate, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1097952019-01-14T03:32:36Z2019-01-14T03:32:36ZHow is oxygen ‘sucked out’ of our waterways?<figure><img src="https://images.theconversation.com/files/253587/original/file-20190114-43544-kywlhi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dead fish are a source of food for bacteria, which then extract oxygen from the river. </span> <span class="attribution"><span class="source">AAP</span></span></figcaption></figure><p>A million fish <a href="https://www.farmonline.com.au/story/5847386/menindee-fish-kill-how-did-we-get-here/">have died </a>in the Murray Darling basin, as oxygen levels plummet due to major algal blooms. Experts have warned we could see more mass deaths this week. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-what-causes-algal-blooms-and-how-we-can-stop-them-109646">Explainer: what causes algal blooms, and how we can stop them</a>
</strong>
</em>
</p>
<hr>
<p>Fingers have been pointed at <a href="https://www.abc.net.au/radionational/programs/breakfast/murray-darling-authority-blames-historic-water-mismanagement/10707358">poor water management</a> after a long period of drought. However, mass fish deaths can also be caused by <a href="https://www.mdba.gov.au/media/mr/blackwater-widespread-after-river-murray-floods">floods</a>, and even raw sewage. </p>
<p>So what’s going on when oxygen gets “<a href="https://www.washingtonpost.com/local/officials-algae-bloom-suffocated-thousands-of-fish-to-death-in-anne-arundel-creeks/2012/05/23/gJQAlHBQkU_story.html?noredirect=on&utm_term=.56d73e28c58d">sucked out of the water</a>”?</p>
<p>The phenomenon is very well known to water quality engineers; we call it “<a href="https://en.wikipedia.org/wiki/Biochemical_oxygen_demand">biochemical oxygen demand</a>”. To understand it, we need to talk about a little bit of biology and a little bit of chemistry.</p>
<h2>When oxygen meets water</h2>
<p>Oxygen molecules are soluble in water in the same way that sugar is soluble in water. Once its dissolved, you can’t see it (and, unlike sugar, oxygen is tasteless).</p>
<p>The maximum amount of oxygen that you can dissolve in water depends on a number of factors, including the water temperature, ambient air pressure, and salinity. But roughly speaking, the maximum amount of dissolvable oxygen, known as the “saturation concentration” is typically around 7-10 milligrams of oxygen per litre of water (7-10 mg/L).</p>
<p>This dissolved oxygen is what fish use to breathe. Fish take water in through their mouths and force it through their gill passages. Gills, like our lungs, are full of blood vessels. As water passes over the thin walls of the gills, dissolved oxygen is transferred into the blood and then transported to the fish’s cells. The higher the oxygen concentration in the water, the easier it is for this transfer to occur.</p>
<p>Once in the cells, the oxygen molecules play a key role in the process of “aerobic respiration”. The oxygen reacts with energy-rich organic substances, such as sugars, carbohydrates and fats to break them down and release energy for the cells. The main waste product from this process is carbon dioxide (CO₂). This is why we all need to breathe in oxygen and we breathe out carbon dioxide. Fish do that too. A simple way to express this is: </p>
<blockquote>
<p>Organic substances + Oxygen <strong>→</strong> Carbon dioxide + Water + Energy</p>
</blockquote>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253588/original/file-20190114-43535-1ug4rx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Hunter River in NSW suffered a ‘blackwater’ event in 2016 when floodwaters washed organic matter into the river.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/fishyone1/8656877471/in/photolist-ebYL58-GuAxFi-buSxYC-z3sHAC-fme1DD-St3t6w-Ty6ocr-e55Wyx-71NNaQ-6fYpAT-71NN7w-RHG8LB-S1zBex-RFezrY-QV76Pq-S9K9Yo-RDyqed-S91LqS-EDSL4Q-2j7DqY-F9mCKh-RHG9ti-CAeVuQ-D5oh6-RGYU4q-fC2mGs-9ncWH2-9ncWJv-VD65hC-mtEuy-Sc3mbh-u63Lh-gR1pEh-D5nJc-Ty6naB-5W83b5-St3sP9-3EvNxZ-TKADyi-Sb3rHV-D5nPv-FDGejb-ji7vDV-e9YFqS-D5ocQ-D5on9-26JwULu-aDoagB-Si2Mvv-aX3QXa">Andrew S/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>What is the <em>biochemical oxygen demand</em>?</h2>
<p>Just like fish and people, many bacteria gain energy from processes of aerobic respiration, according to the simplified chemical reaction shown above. Therefore, if there are organic substances in a waterway, the bacteria that live in that waterway can consume them. This is an important process of “biodegradation” and is the reason our planet is not littered by the carcasses of animals that have died over many thousands of years. But this form of biodegradation also consumes oxygen, which comes from dissolved oxygen in the waterway.</p>
<p>Rivers can replenish their oxygen from contact with the air. However this is a relatively slow process, especially if the water is stagnant (flowing creates turbulence and mixes in more oxygen). So if there is a lot of organic matter present and bacteria are feasting on it, oxygen concentrations in the river can suddenly drop.</p>
<p>Obviously, “organic substances” can include many different things, such as sugars, fats and proteins. Some molecules contain more energy than others, and some are easier for the bacteria to biodegrade. So the amount of aerobic respiration that will occur depends on the exact chemical nature of the organic substances, as well as their concentration. </p>
<p>Therefore, instead of referring to the concentration of “organic substances”, we more commonly refer to the thing that really matters: how much aerobic respiration the organic substances can trigger and how much oxygen this will cause to be consumed. This is what we call the <em>biochemical oxygen demand</em> (BOD) and we usually express it as a concentration in terms of milligrams of oxygen per litre of water (mg/L).</p>
<p>Like us, bacteria don’t consume all of the food which is available to them instantly – they graze on it over time. Biodegradation therefore can take days, or longer. So when we measure the BOD of a contaminated water sample, we need to assess how much oxygen is consumed (per litre of water) over a specified period of time. The standard period of time is usually five days and we refer to this value as the BOD5 (mg/L).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253590/original/file-20190114-43525-19m1fdz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Murray cod pull oxygenated water through their gills, transferring it to their bloodstream. Without oxygen in the water, they die.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/guochai/1292824702/in/photolist-2Yf4K5-8xW2iy-8xSZ6B-8xW2gW-cBYHsu-27c8rtW-96HaXU-HnKMwP-TBMM1X-eQifMT-72Pjt7-HB6XfP-j9oPN-52uxN-7p96Tq-5kX7uP-5HTBuH-5HTDf2-rd6XeD-5HTDHk-5HTG16-UD8kbh-5HTCnx-5hdMKF-5HXSYy-5HTC3c-5HTCSc-5HTDZZ-VESXhd-VJafgn-8MvmSc-VVzpzc-27c8qCY-5HTDxD-UG5PRv-UG48Ji-eatLpZ-UD8jH3-5HXVBb-BTkoP8-UD8k55-52Md5n-UD8jJf-VJabVV-UG3Rvg-dEJDZf-VkptbE-VVB8FV-UgkTd7-26o6cdB">Guo Chai Lim/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-sa/4.0/">CC BY-NC-SA</a></span>
</figcaption>
</figure>
<p>As I mentioned earlier, clean water might only have a concentration of dissolved oxygen of up to around 7-10 mg/L. So if we add organic material in a concentration which has a higher BOD5 than this, we can expect it to deplete the ambient dissolved oxygen concentration during the next five days.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/more-of-us-are-drinking-recycled-sewage-water-than-most-people-realise-92420">More of us are drinking recycled sewage water than most people realise</a>
</strong>
</em>
</p>
<hr>
<p>This phenomena is the main reason for which biological sewage treatment was invented. Raw (untreated) municipal sewage can have a BOD5 of 300-500 mg/L. If this were discharged to a clean waterway, the typical base-level of 7-10 mg/L of oxygen would be consumed, leaving none available for fish or other aquatic organisms. </p>
<p>So the purpose of biological sewage treatment is to grow lots of bacteria in large tanks of sewage and provide them with plentiful oxygen for aerobic respiration. To do this, air can be bubbled through the sewage, or sometimes surface aerators are used to churn up the sewage. </p>
<p>By supplying lots of oxygen, we ensure the BOD5 is effectively consumed while the sewage is still in the tanks, before it’s released to the environment. Well treated sewage can have a BOD5 as low as 5 mg/L, which can then be further diluted as it’s discharged to the environment.</p>
<p>In the case of the Darling river, the high BOD load was created by algae, which died when temperatures dropped. This provided a feast for bacteria, lowering oxygen, which in turn killed hundreds of thousands of fish. Now, unless we clean the river, those rotting fish could become fodder for another round of bacteria, triggering a second de-oxygenation event.</p><img src="https://counter.theconversation.com/content/109795/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stuart Khan is affiliated with the Australian Water Association, and is on a water quality advisory committee for the NHMRC. </span></em></p>Hundreds of thousands of fish have died in low-oxygen water. Here’s what actually happened to the oxygen, and why we might see more deaths in the coming weeks.Stuart Khan, Professor of Civil & Environmental Engineering, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1096462019-01-10T03:41:40Z2019-01-10T03:41:40ZExplainer: what causes algal blooms, and how we can stop them<p>Outbreaks of algae have killed up to a <a href="https://www.abc.net.au/news/2019-01-08/second-fish-kill-in-darling-river-at-menindee/10696632">million fish</a> in the Murray Darling Basin over the last two weeks. The phenomena of “algae blooms”, when the population of algae in a river rapidly grows and dies, can be devastating to local wildlife, ecosystems and people. But what are algae blooms? What causes them, and can we prevent them?</p>
<p>Microscopic algae are fundamental to life on earth. These tiny plants provide the fuel that drives marine and freshwater foodwebs, and via photosynthesis, they gobble up carbon dioxide to help counteract emissions, and provide us with oxygen to breathe. Besides rivers, streams, lakes, estuaries and the coast, they can also be found in <a href="https://en.wikipedia.org/wiki/Algae#Distribution">diverse environments</a> such as snow, soil, and in corals.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526">Are toxic algal blooms the new normal for Australia's major rivers?</a>
</strong>
</em>
</p>
<hr>
<p>But when humans channel agricultural run-off, sewerage and stormwater discharge into waterways, we dramatically increase the amount of nutrients such as nitrogen and phosphorus. This creates an imbalance, because some microscopic algae are supremely effective at mopping up nutrients and can grow very quickly, dividing up to once a day and quickly overtaking other species. The result is an algal bloom.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=624&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=624&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=624&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=785&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=785&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253164/original/file-20190110-32145-yyz9mi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=785&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cyanobacteria (blue-green algae) under a microscope.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>So why don’t we have algal blooms all the time? This is because algae don’t just require nutrients to grow. Like any plant, factors such as temperature and light availability are also important in determining how quickly algae grow and whether they form blooms. Blooms also need slow moving or still water to become established.</p>
<p>In Australia, our algal blooms are typically in freshwaters. The main group of algae responsible for this are known as blue-green algae, or more accurately, cyanobacteria. They regularly bloom in warmer weather in our reservoirs, lakes and slow flowing rivers. In 2016, for example, <a href="https://theconversation.com/are-toxic-algal-blooms-the-new-normal-for-australias-major-rivers-59526">1,700km of the Murray River</a> was affected by an algal bloom. </p>
<p>There are many ways they impact the environment and economy. Some algal blooms are toxic, requiring expensive water treatment and – in extreme cases – shutdown of water supplies. This isn’t just a problem in Australia. In 2014, some <a href="https://www.ecowatch.com/toxic-algae-bloom-leaves-500-000-without-drinking-water-in-ohio-1881940537.html">500,000 people</a> in the US were left without drinking water due to a toxic algal bloom in Lake Erie.</p>
<p>The toxins can also affect domestic animals, such as dogs, when they drink contaminated water, and limit use of lakes and rivers for swimming, boating and fishing. Even when algal blooms are not toxic, they unbalance the food web, reducing the number of species of animals and plants. </p>
<p>They can also reduce oxygen levels at night, as they switch from photosynthesis (producing oxygen) during the day, to a process called <a href="https://en.wikipedia.org/wiki/Cyanobacteria#Respiration">respiration</a> at night where they use oxygen. Low oxygen can stress and even kill fish and other animals if they cannot escape this.</p>
<p>At some point, algal blooms crash when conditions become unsuitable. The resulting dead algae break down, providing an ideal food source for bacteria. This is when waters can become smelly, often with a rotten egg smell. As the bacteria multiply, they suck the oxygen out of the water. At this point, oxygen levels become low both day and night. </p>
<p>If the area of low oxygen is extensive, such as a whole lake or many kilometres of a river system, fish and other animals may not be able to escape to more suitable oxygen levels, and major fish deaths typically occur.</p>
<p>In other areas of the world, algal blooms have caused such severe oxygen conditions that thousands of square kilometres of ocean around the world are now known as <a href="https://www.scientificamerican.com/article/oceanic-dead-zones-spread/">dead zones</a>, where no animals can live. These vast dead zones are not something we ever want to see in Australia.</p>
<h2>So what can be done about blooms?</h2>
<p>There are a wide range of <a href="https://www.epa.gov/nutrient-policy-data/control-and-treatment">treatments</a> that can be used to control blooms, for example, aerating the water, and adding clays and chemicals, but the catch is they are <a href="http://www.owrb.ok.gov/quality/standards/pdf_standards/scenicrivers/Dodds%20et%20al%202008.pdf">very expensive</a> on a large scale. </p>
<p>Ideally, the problem should be tackled at the source. This means reducing nutrient loads to our waterways. There has already been progress on this in our cities where sewage treatment plants have been upgraded to <a href="https://www.scientificamerican.com/article/wastewater-is-key-to-reducing-nitrogen-pollution/">reduce nutrient loads</a> to waterways. But tackling nutrients coming from agriculture – erosion, fertilisers, animal waste – is much more <a href="https://environment.des.qld.gov.au/assets/documents/reef/costings-report.pdf">challenging and expensive</a> because of the vast areas involved. So this remains work in progress.</p>
<p>It’s also very difficult to <a href="https://www.smithsonianmag.com/science-nature/can-scientists-forecast-algal-blooms-pest-outbreaks-like-we-do-weather-180967998">predict when blooms will occur</a>; despite being simple plants, algae have an amazing range of strategies to grow and survive. But as we learn more about their complexity our ability to model and predict blooms will improve. This is crucial to managing risks to water supplies and preventing major environmental effects, such as fish deaths.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/toxin-linked-to-motor-neuron-disease-found-in-australian-algal-blooms-95646">Toxin linked to motor neuron disease found in Australian algal blooms</a>
</strong>
</em>
</p>
<hr>
<p>Ultimately there are no quick fixes to algal blooms. Given the pressure we put on our waterways, they are here to stay. In fact they are likely to increase due to increasing temperatures and more extreme conditions, such as droughts. We know what we need to do to reduce the scale and likelihood of blooms: the challenge is devoting the resources to achieve it.</p><img src="https://counter.theconversation.com/content/109646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michele Burford receives funding from the Australian Research Council, State and local governments for her algal research.</span></em></p>Algae blooms have killed hundreds of thousands of fish in the last two weeks, but what exactly are they and how do we get them under control?Michele Burford, Professor - Australian Rivers Institute, and Dean - Research Infrastructure, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.