The exodus begins April 1.

That's the message from immigration lawyers and labour market analysts who say that Canada — and in particular Alberta — is due to lose thousands, maybe tens of thousands, of temporary foreign workers in the coming weeks and months.

They're saying hotel rooms won't be cleaned, double-doubles won't be poured, and the workers themselves will have to give up the dream of a better life in Canada.

We're relying on anecd otal stories from our members. — Mark von Schellwitz, Restaurants Canada

That is all possibly true, but the problem is that Citizenship and Immigration Canada won't share the number of temporary foreign workers about to lose their work visas, and everyone else is depending on anecdotes, extrapolation and educated guesses.

Here are the numbers that we do know, using the Alberta example, since it has the most temporary foreign workers﻿.

As of the end of 2013, Alberta had nearly 41,000 temporary foreign workers who were brought to Canada because their employers said they couldn't find qualified Canadian staff. There are many thousands more here on the international mobility program.

The federal government estimates that Alberta will lose 8,047 low-wage temporary foreign workers by July 2016.

1,000 temporary foreign workers ﻿ who had applied for permanent residency in Alberta were offered a one-year reprieve while they waited for their applications to be processed.

Not clear how many have to leave

Here's what we don't know — how many are set to leave April 1. Temporary workers who have been working in Canada since April 1, 2011, will see their visas expire, unless they were given the one-year reprieve.

Migrante Canada says that based on the number of people asking for help in Alberta, 16,000 are vulnerable. But that doesn't mean they all have to leave April 1.

"Well it's a rolling number," says Gil McGowan, president of the Alberta Federation of Labour. "Because it depends on when their employers got their approval and the workers got their visa."

In June, the federal government made changes to the temporary foreign worker program after numerous abuses were reported by CBC News.

The changes included a ban on low-wage temporary foreign workers in regions where the unemployment rate is higher than six per cent and ultimately a 10 per cent cap in areas where unemployment is lower. Low-wage temporary foreign workers are defined as workers who earn less than the median income of approximately $20 per hour, depending on your province.

"We're relying on the anecdotal stories from our members," says Mark Von Schellwitz, vice-president of Western Canada with Restaurants Canada. "We don't have accurate numbers how many are leaving, but we know we're losing quite a lot of people as of Wednesday."

They didn't do anything wrong, they were used as pawns. — Gil McGowan, president of the Alberta Federation of Labour

Whatever the number is, the debate rages on over two issues: Do we still need temporary foreign workers, and what do we owe the ones who have been here for many years?

Does Canada need temporary foreign workers?

Yes, says industry. No, say unions.

Gil McGowan of the Alberta Federation of Labour says that we need to save the first rungs of employment for new immigrants, students and seniors.

(Source: Citizenship and Immigration Canada) "We question whether we ever needed them [temporary foreign workers]. In fact, we've been saying for years that all this talk about labour shortage was dramatically overblown, and it was a cover for providing employers with a mechanism that keep wages low when economic conditions suggest that they should go up. The program needs to go."

That assumes that students and seniors need to take the first rung on the job ladder. What if there are better options?

Not all people are willing to take all jobs, says Farahnaz Bandali, a senior policy analyst with the Canada West Foundation. "So a high-skilled oil worker may not be willing, even if they are recently unemployed, to take a low-skilled job previously held by a temporary worker."

"And there is a market for youth labour, but youth aren't willing to work the graveyard or overnight shift."

Mark von Schellwitz agrees. "The difficulty with high school students is that there are a lot fewer of them each year entering the workforce. For our industry that relies on them, that's a good reason right there for our labour shortage."

Von Schellwitz says that it is a larger problem in rural parts of the country than in the cities.

What does Canada owe existing workers?

​Many people will think we owe temporary workers nothing — the jobs were temporary after all.

A poster shows the concern of the fast food industry in Alberta. (Shawna Miller ) But Bandali says that workers might have been temporary, but the jobs are permanent, and that the program created to fill temporary jobs has changed over the years.

"In some ways it's our own fault; these people were going to come in and fill temporary jobs and now they're filling permanent jobs, which is where the disconnect is happening."

Even though McGowan of the Alberta Federation of Labour thinks the program needs to be killed, he has sympathy for the workers still here in Canada.

"They didn't do anything wrong; they never deserved the treatment they got," says McGowan. "I've sent a letter to Jason Kenney asking that the temporary foreign workers currently in the country be grandfathered and be allowed permanent residency and eventual citizenship.

"They didn't do anything wrong, they were used as pawns by a broken program to drive down wages."