As the rain-soaked spring continues, the head of Toronto Water says he's concerned about Thursday and Friday's forecast.

Environment Canada has issued a rainfall warning, saying between 40 and 70 millimetres will fall between Thursday and Saturday. Normally, Lou Di Gironimo says, Toronto's system can handle that.

But right now, the ground is completely saturated after weeks of rain and Lake Ontario is at the highest level it's been in years. And that will put a big pressure on the city's sewers.

"We are on alert, more alert than we typically would be with a storm of this size," Di Gironimo told CBC Toronto.

"It'll be a tense few days."

Di Gironimo says storms are often more severe in different parts of the city, and says crews will be dispatched wherever they're needed.

"We don't know exactly where it's going to hit, so we have to be ready to respond and that's always a bit of a challenge."

Before the rain starts, the city is urging residents to make sure their catch basins are clear of debris and that their gutters are clear as well. Anyone who spots serious flooding should call 3-1-1, Di Gironimo said.

City to consider new way to pay for stormwater plans

There's also a potential political storm brewing when it comes to these issues.

The public works committee is set to discuss an update to the city's wet weather master plan next week. The plan, started back in 2003, covers everything from major infrastructure builds, including a tunnel system in the Don River, to programs that help people avoid flooding in their basements.

Carrying it out will cost some $3 billion by 2026 to be paid for by water bills. However, Mayor John Tory's executive committee is set to review the idea of paying for the program with a separate stormwater fee.

Coun. Jaye Robinson, chair of the public works committee, says she's not sure council will support that despite the effects of recent storms.

"Right now, I don't sense that there's an appetite on council, but I think we need to address it," she said.