{"id":257068,"date":"2025-12-30T00:32:14","date_gmt":"2025-12-30T00:32:14","guid":{"rendered":"https:\/\/www.europesays.com\/ie\/257068\/"},"modified":"2025-12-30T00:32:14","modified_gmt":"2025-12-30T00:32:14","slug":"south-east-queenslands-largest-dam-is-full-what-does-it-mean","status":"publish","type":"post","link":"https:\/\/www.europesays.com\/ie\/257068\/","title":{"rendered":"South-east Queensland’s largest dam is ‘full’. What does it mean?"},"content":{"rendered":"

With the wet season only just underway, it might make some a little nervous to hear south-east Queensland’s biggest reservoir \u2013 Wivenhoe Dam \u2013 is just about full.\u00a0<\/p>\n

But the people in charge of the dam say water levels are exactly where they need to be.<\/p>\n

Located north-west of Brisbane, Wivenhoe Dam is one of 26 dams operated by Seqwater \u2013 and is by far the biggest of the lot.<\/p>\n

When deemed ‘full’, the dam can hold just under 1.2 million megalitres.<\/p>\n

In comparison, the next largest \u2013 Somerset \u2013 is around a third of the size.<\/p>\n

Why Wivenhoe?\"An Wivenhoe Dam provides drinking water and flood protection for much of the state’s south-east.(Supplied: Seqwater)<\/p>\n

Completed in 1984, Wivenhoe Dam was built with the primary purpose of providing drinking water to the millions of people who live in south-east Queensland.<\/p>\n

Its secondary function is to mitigate flooding by controlling the flow of both the Brisbane and Stanley Rivers which pass through some of the heaviest rainfall areas in the country.<\/p>\n

Data on flooding in the city of Brisbane dating back to the 1890s shows in that regard, it has been very successful.<\/p>\n

But the operators of the dam warn that even with the best management strategy in place, Wivenhoe will not hold back the next major flood.<\/p>\n

How much water can it hold?<\/p>\n

A search online for ‘Wivenhoe dam level’ will give you a percentage somewhere between 80-90 per cent.<\/p>\n

However, to use official jargon, that means “operational supply level” and is a percentage of its total drinking water supply level, not its actual capacity.\u00a0<\/p>\n

That means that during a flood event, Wivenhoe can hold far more than 1.2 million megalitres.<\/p>\n

\"A The flood operations centre uses complex software to monitor rainfall and river conditions.(ABC News: Will Murray)<\/p>\n

Seqwater’s principal dam safety and operations manager Kevin Bartlett said this is thanks to an additional compartment located above the drinking water.<\/p>\n

“It’s double the size,” he explained.<\/p>\n

“So, there’s another two million megalitres of flood storage available.”<\/p><\/blockquote>\n

In a flood, instead of that additional water rushing downstream as it would naturally, the dam allows Seqwater to release it in a more controlled manner through Wivenhoe’s five gates.<\/p>\n

When are the floodgates opened?<\/p>\n

Which gates to open, when to do so, and by how much, is determined by engineers based at Seqwater’s flood operations centre, which is based in Brisbane.<\/p>\n

They rely on an array of hundreds of sensors dotted across the catchment which provide real-time data on rainfall, run-off, flow rates and dam levels.<\/p>\n

Forecasts from the Bureau of Meteorology are also used to model how a flood event will play out.<\/p>\n

\"Photo Wivenhoe Dam’s floodgates are used to control the flow of water during rain events.(ABC News: Will Murray)<\/p>\n

Wivenhoe’s floodgates are used to control the flow of water during rain events.<\/p>\n

\"Photo Hundreds of sensors arranged across the catchment provide data on rainfall, runoff, flowrates and dam levels.(ABC News: Will Murray)<\/p>\n

Hundreds of sensors arranged across the catchment provide data on rainfall, run-off, flow rates and dam levels.<\/p>\n

\"photo Weather forecasts from the Bureau of Meteorology are also taken into account when deciding which gates to open.(ABC News: Will Murray)<\/p>\n

Weather forecasts from the Bureau of Meteorology are also taken into account when deciding which gates to open.<\/p>\n

As the dam fills above operational full supply level, the engineers direct that the gates start to open in accordance with the Wivenhoe flood manual.<\/p>\n

“[The manual] effectively sets all of the processes we follow \u2013 how we release, when we release,” Mr Bartlett said.<\/p>\n

“Once we get only a very small margin above that operational full supply level, we must actually open gates.”<\/p><\/blockquote>\n

\"A Floodgates are opened to control the dam’s capacity during severe weather events.(Supplied: Seqwater)The lessons of 2011<\/p>\n

After the 2011 floods, the operators of Wivenhoe were accused of breaching their duty by failing to follow the flood manual.<\/p>\n

In 2019, the Supreme Court of New South Wales found Seqwater and others had been negligent <\/a>\u2013 essentially by not releasing water soon enough.<\/p>\n

Seqwater later won an appeal against that decision<\/a>, successfully arguing that the senior flood manager at the time followed a legitimate strategy.<\/p>\n

\"A Severe flooding in 2011 led to the reviewing of the dam’s processes for dealing with floods.(Supplied: Angus Veitch)<\/p>\n

However, it prompted several reviews of the flood manual and explains why today’s engineers are so devoted to its stipulations.<\/p>\n

The floods of 2011 also prompted political calls to drain Wivenhoe to below full supply level ahead of forecast heavy rain.<\/p>\n

But the manual does not allow for that, and in fact requires that the dam be kept as close to full supply as possible.<\/p>\n

\"A Seqwater CEO Emma Thomas says the primary function of Wivenhoe Dam is to provide drinking water.(ABC News: Will Murray)<\/p>\n

Seqwater chief executive Emma Thomas explained that is because forecasts can be unreliable and the next drought could be just around the corner.<\/p>\n

“Our primary purpose is to provide drinking water to south-east Queensland to over 3.7 million people,” she said.<\/p>\n

“We have to provide that water to them.”<\/p>\n

The Wivenhoe myth<\/p>\n

Even if operated in full accordance with the manual, operators say Wivenhoe will not be able to stop a major flood from affecting those downstream.<\/p>\n

That’s because only the upper Brisbane and Stanley Rivers are controlled by the Wivenhoe and Somerset dams.<\/p>\n

\"A Wivenhoe and Somerset dams control the upper Brisbane and Stanley rivers, but not Lockyer Creek, Bremer River or the lower Brisbane River.(ABC News: Will Murray)<\/p>\n

Other waterways, including the volatile Lockyer Creek, Bremer River and lower Brisbane River, are all unregulated.<\/p>\n

“We only can control half of the overall catchment to Brisbane,”<\/p><\/blockquote>\n

Mr Bartlett said.<\/p>\n

“So, flooding can occur naturally.”<\/p>\n

During a particularly severe event, dam operators lose some of the limited control they have, because Wivenhoe is designed to spill over once it reaches a certain level to prevent a catastrophic structural failure.<\/p>\n

\"Workers Dam operators have been conducting maintenance ahead of summer.(ABC News: Will Murray)<\/p>\n

However, when possible, controlled releases are timed so as not to make that naturally-occurring flooding worse.<\/p>\n

“[During ex-tropical cyclone Alfred] we were able to wait for the peaks to come up in those downstream catchments and to pass through before we started to increase our releases from Wivenhoe,” Mr Bartlett said.<\/p>\n

Stay alert, be preparedFloods don’t always move slowly, prepare now<\/a><\/p>\n

Floods can devastate large areas and it’s important to know the risk of flooding at your home. Make sure your property is prepared because floods can happen quickly.\u00a0<\/p>\n

Dam releases regularly cause Brisbane River crossings to be impassable, and dangerously charge downstream waterways.<\/p>\n

Ms Thomas said Seqwater notifies local governments and disaster management teams as early as possible regarding releases.<\/p>\n

But she warned advanced notice was not always possible.<\/p>\n

“We’re all part of the community as well and would like as much notification as possible,” Ms Thomas said.<\/p>\n

“But I think we all understand that our weather is very changeable, and we all need to be able to react and respond.”<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"With the wet season only just underway, it might make some a little nervous to hear south-east Queensland’s…\n","protected":false},"author":2,"featured_media":257069,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[269],"tags":[133035,133030,133031,133027,18,440,27185,133029,19,17,25410,27315,3118,133,133036,133028,133032,133033,133034,133026],"class_list":{"0":"post-257068","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-environment","8":"tag-2011-floods","9":"tag-bremer-river","10":"tag-brisbane-river","11":"tag-dam","12":"tag-eire","13":"tag-environment","14":"tag-flood","15":"tag-flood-control","16":"tag-ie","17":"tag-ireland","18":"tag-rain","19":"tag-rainfall","20":"tag-river","21":"tag-science","22":"tag-seqwater","23":"tag-south-east-queensland-water","24":"tag-stanley-river","25":"tag-water-management","26":"tag-water-policy","27":"tag-wivenhoe"},"share_on_mastodon":{"url":"https:\/\/pubeurope.com\/@ie\/115805706696717270","error":""},"_links":{"self":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/257068","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/comments?post=257068"}],"version-history":[{"count":0,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/posts\/257068\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media\/257069"}],"wp:attachment":[{"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/media?parent=257068"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/categories?post=257068"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.europesays.com\/ie\/wp-json\/wp\/v2\/tags?post=257068"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}