Joni Rynsburger-Rathwell says the decision to move out of her riverfront property on Saskatchewan Crescent East came swiftly.

"I stepped outside and saw there was some dirt moving toward the house over our retaining wall in the back," she said

That was back in the spring. Over the space of a couple days, the slope that rises behind her house slipped more than a metre toward her house.

Slope sliding to river

The city had been monitoring the stretch of riverbank since June 2012. This rapid movement so alarmed engineers that the city issued a voluntary evacuation notice. It was aimed at eight homeowners in an unstable zone near Victoria Avenue. 

The Rynsburger-Rathwells took it seriously.

'We've actually moved out' - Joni Rynsburger-Rathwell
Joni and Zander

Joni Rynsburger-Rathwell and her son, Zander

"We're not in here, we've actually moved out. We're the only residents that have moved out, we're the most affected right now," she said.

"We have two young children and I was laying in bed at night thinking what if there's a tree falling on our house, which is probably more than what would have happened but I just wasn't feeling comfortable."

A muddy mystery

No one knows exactly why this particular stretch of riverbank is suddenly so unstable. So far, the city says it's affecting more than 20 high-end properties overlooking the South Saskatchewan River.

Ahmed El-Serafi lives in the condominiums beside the Rynsburger-Rathwells. He's a retired electrical engineer from the University of Saskatchewan.

Ahmed El-Serafi

Ahmed El-Serafi

​ El-Serafi's has lived in the Buena Vista area since the early 1980s. His window looks out on the shifting bank.

Looking up the slope to the line of properties along 11th Street East, he thinks he knows what's happening.

'I think it was a mistake building a lot of houses on the edge of the slope' - Ahmed El-Serafi

"I think it was a mistake building a lot of houses on the edge of the slope. There is no retaining wall on the back lane, and that has caused the whole thing," he said.

"Our building has a retaining wall in advance so it is not affected too much. It is on this side and on this side."

The City is confident

Andrew Hildebrandt is the City of Saskatoon's storm water utility manager.

He says a $350,000 report by Golder Associates due next month will help clarify what's happening.

Andrew Hildebrandt

Andrew Hildebrandt

Hildebrandt says the Golder report is expected to explain what's happening with the slope, offer a range of possible fixes and significantly, lay out potential costs to the City.

“In a situation that can seem relatively hopeless and quite severe, and that’s what we’ve seen this July with the amount of movement," Hildebrandt said.

"We are confident we have the experts available to be able to provide us the recommendations and expertise we need to actually physically solve it and stop it from moving.”

He says the City issued its voluntary evacuation notice because of the rapid shift this summer. A mandatory notice could follow should engineers decide people are at risk.

Hildebrandt said this would be based on actual movement of buildings.