Today marks one year since the start of a flood forced roughly 100,000 people from their homes in southern Alberta.

Four people drowned in floodwaters and a fifth was killed in an ATV accident while helping a neighbour sandbag.

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Alberta Premier Dave Hancock gestures during a ceremony commemorating the first anniversary of devastating floods that hit Calgary in 2013. (Jeff McIntosh/Canadian Press)

The deluge swept through 30 communities and caused an estimated $6 billion in damage — the most costly natural disaster in Canadian history.

“We’re also taking steps to ensure we’re more prepared than ever in the event of another major flood," said Premier Dave Hancock. 

"Just this week, several communities in southern Alberta declared states of local emergency due to heavy rainfall and threats of overland flooding. It’s situations like these that remind us we always need to be prepared and ready."

Ceremonies held

Commemoration ceremonies are being held all over the region, including in High River and Calgary, which were particularly hard hit.

“Our city and citizens experienced a devastating flood that we will never forget," said Mayor Naheed Nenshi in a release.

“We come together today to remember how the flood affected us in both tangible and intangible ways. But, more important, we recall the incredible resilience and community spirit shown by all Calgarians this time last year. With the help of the entire community and all orders of government, we were, and continue to be, stronger than ever.”

Nenshi unveiled a 2013 Flood Commemorative Display, which included a plaque and pair of bronzed boots that are permanently housed in the Municipal Building’s Atrium for public viewing. The unveiling also included the Children’s Flood Art Display.

Prime Minister Stephen Harper and his wife, Laureen, appeared on a video in Calgary, where officials and the public gathered in the municipal building to mark the anniversary.

The prime minister recalled the "dark days" of June 2013.

"One year ago some parts of our great province were under water. Property was destroyed, homes were washed away and precious memories lost," he said.

But people never lost heart, added his wife.

"I will always remember the summer of 2013, not because of the height of the floodwaters, but because of the strength of the people here and the generosity of all Canadians," the prime minister said.

Still picking up the pieces

NDP leader Brian Mason says today Albertans also recognize the extraordinary efforts of volunteers and frontline staff throughout the province.

“When we remember the floods, we think not only of the devastating power of water and weather, but of the strength of community spirit in our province," he said.

However, Wildrose Party leader Danielle Smith says many Albertans are still picking up the pieces as they rebuild.

“My hometown of High River was hit particularly hard, with about three quarters of the homes in town damaged by floodwaters," she said. "A year later, I still see daily reminders — boarded up houses and abandoned properties — of the flood that tore through our community."

Liberal Leader Raj Sherman says there is much work left to be done, including tracking where taxpayers money is being used. The party had called for a special auditor to monitor flood-related expenses in real time.

“Whenever disaster hits, money flows,” says Alberta Liberal Leader Raj Sherman. “A responsible government would take every step possible to ensure public money goes to where it is needed the most. A special auditor would have made sure the money was spent wisely.”

With files from CBC