GNS and geotechnical engineers are working on modelling scenarios for what would happen if the dam was to breach.
"Essentially there's a large pool of water building behind the newly created dam," Sinclair said.
"The water is about 200 to 300 metres in length and 10 metres wide. Based on that information and the forecast we made the decision to evacuate as if that dam fails that's a lot of water that could come rushing down, which would most likely pick up debris, and end up in the low-lying areas."
Evacuated residents were advised to be prepared to be gone for at least 10 days. Civil Defence said none of them needed emergency accommodation.
Goose Bay resident John Mahony told the Herald having to evacuate was a "pain in the neck".
"But you've got to do what you've got to do, when you've got to go you've got to go."
He was told at the meeting that fears the dam will flood their homes has meant they have to leave.
"Basically we were told that we have to go because this thing might burst."
Residents are frustrated at having to leave, Mahony said.
"A lot of us live 100m up the hill from the creek, and we're a bit pissed off we can't stay but hey, we'll go."
He said they've been given no definite time-frame for when they will be able to return home.
"They don't know, they've got no idea really. It could be a couple of days, could be a couple of weeks, whenever.
"We're just sitting around a bit and answering the phone because that's going flat out, and packing up a bit."
He was planning on taking "just a few clothes, that's all you need really, and a toothbrush".
Mahony plans on staying with mates nearby.
"We're just going 500m around the corner to a friend's place, so we're not going far. And there's a few people who are going to camp at the harbour a few kilometres up the coast."