00:00It's a beautiful, still day on the Hewan River.
00:05The water here in Hewanville flows all the way from Lake Pedder, about 100 kilometres
00:10away, where there's two dams built alongside an active fault line.
00:15Edgar Dam and Scots Peak Dam were built in the 1970s, but recent research shows there
00:21have been three earthquakes on the fault line of up to magnitude 6.9 in the past 60,000
00:27years.
00:28It's not necessarily going to happen in a lifetime of mine, but the things do happen.
00:35Hydro Tasmania created flood modelling to show what would happen in the unlikely event
00:40of the dams failing, but chose to keep it under wraps to avoid causing unnecessary concern.
00:46Eight years later, it's been released under Right to Information to the Tasmanian Greens.
00:52The modelling suggests if Edgar Dam breaks, a flood peak of at least nine metres would
00:57flow down the Hewan, arriving at Hewanville after 12 hours, where it would start to spread.
01:03To put this into context, we're talking about a likelihood of one in 10,000.
01:07Buildings throughout the centre of the town would be inundated by metres of flood water,
01:12including the council offices, the police station and the SES headquarters.
01:18The council also called for the modelling to be released in the interests of emergency
01:22planning.
01:23It's no different than a bushfire or any of the events that we could have.
01:29It's those three things that you have to have your plan.
01:32Mock evacuations were carried out, but the flood mapping still wasn't publicly released
01:36by Hydro, meaning most residents are unaware.
01:39To actually inform them of what would happen if either of those dams were to fail, what
01:45the evacuation procedures would be.
01:47These maps, they're made really for emergency services response and scenario planning to
01:53be able to pull into action, so by nature then they look at the worst case, they're
01:57very pessimistic.
01:58Works to strengthen Edgar Dam have now been approved, and planning is underway to upgrade
02:04Scott's Peak Dam.
02:06But back in Hewanville, locals weren't letting something that has a one in 10,000 chance
02:10of happening per year ruin their day.
02:13Well if everything worries you like that, you know, have a big headache I suppose.
02:19You can spoil a lot of life by worrying about something that may never happen, and what
02:24can you do?
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