In 2005, a torrent of water roared into Johnson Shut-ins State park. It swept away the park superintendent's home and critically injured his three small children when the Taum Sauk reservoir gave way. One and a half billion gallons of water swept several vehicles off the road and scoured a swath of land.
Today -- four and a half years and $490 Million later -- that reservoir has been rebuilt, and for the first time we got a look at the changes engineers made to make sure disaster doesn't strike again.
"We regret the tragedy of the Taum Sauk event on December 14, 2005, but its rebuild has been a remarkable recovery."
Those were the first words out of the mouth of Ameren U.E. C.E.O. Tom Voss on the opening day of the rebuilt Taum Sauk reservoir.
When Taum Sauk unleashed its wall of water, it became the worst man-made disaster in Missouri history. Once supported by little more than rock fill, the reservoir now has nearly as much concrete as the Hoover Dam.
Ameren engineers tested its strength and built the retaining wall two feet higher than water ever should be.
More than 100 feet of poured concrete hold one and a half billion gallons of water back, but if it does leak, drains beneath the surface will catch the water, preventing it from weakening the structure. This makes Taum Sauk an industry standard.
"I don't see any reason why this dam would fail," Matt Frerking, managing supervisor of dam safety, says.
Five back-up systems are now in place to prevent another catastrophe. Nine cameras dot the reservoir's perimeter -- giving 24-hour surveillance to crews manning the facility around the clock.
"I can guarantee that it was built with the highest quality and safety in mind," Mark Birk, vice-president of power operations, says.
Ameren U.E. says it revived the reservoir because it's a staple in green energy. The hydro-electric pump helps keep electric bills lower by generating power during peak times of the day.
"It's the biggest battery we have," Birk says.
Fifteen miles away in Lesterville, the hope is for the opening to recharge camping and canoe interest. Sales are still down nearly 50-percent at Twin Rivers Landing.
"People haven't come down here for five years. They didn't think about us," Tammy Howison, owner of the Twin Rivers camp ground, says. "We hope this summer is the first year that we're back to normal levels."