Edmonton will need to spend up to $50 million annually for the next 20  years to flood-proof the city, said the head of the city’s drainage department.

Chris Ward proposed the long-term plan Friday, estimating a start date in 2019.

The city’s drainage system, which dates back to the 1950s, was designed to handle 41 millimetres of rain an hour.

That no longer meets building standards which now call for systems to handle 54 mm.

“If we don't do this, it's the risk that neighbourhoods, homes, private property will get flooded,” he said.

Ward said the city can apply for grants from the federal government to help cover the cost of the upgrade. Alternately, the work could mean an increase in utility bills for Edmontonians, amounting to $.32 per month or about $4 per year.

But first, he said, the city will need to invest about $200 million to deal with Mill Woods and southwest Edmonton, which have flooded in the past. That work would be done over three years, beginning in 2015.

Coun. Mike Nickel said the upgrades are necessary to protect vulnerable parts of the city from future flood damage.

“Drainage is the big thing in Mill Woods,” he said. “For areas like Tweddle and Satou and that part of Mill Woods, their houses have been hit three times in the last eight years with major storms and they've been flooded out. It's got to be fixed.”

City councillors are expected to approve the spending when it comes up for a vote in the next couple of months.