As Congress tackles immigration reform and resentment of laborers from Mexico swells, few are facing the real nature of the crisis.

Every year since 1992, an estimated half million undocumented immigrants have crossed the border illegally to enter the US. That is more people than have immigrated to the US legally over the same period of time.

The US is now home to some 10 million undocumented residents. Never before in history have such a large percentage of American residents been here illegally.

Around 2.5 million of these so-called illegal aliens live in California. One in four—about 600,000, more than 80 percent of whom are Mexican—work in the state’s agricultural industry. And still, with undocumented laborers making up half of the state’s farm labor force, agriculture faces a growing labor shortage.

One small example illustrates the size of the problem: In September, the shortage cost raisin growers in the Central Valley $300,000, as farmers extended the season by nearly a month because they had less than half the people they needed to pick and dry their grapes. “The longer the grapes are out there, the costs just keep piling on,” says Glen Goto, president of the Raisin Bargaining Association in Fresno.

In total, California farmers worked the harvest season with 100,000 fewer workers than they needed, according to the ag trade group Western Growers.

Tom Nassif, president of that trade group, is spearheading a public lobbying campaign that proclaims what for years was too taboo to say out loud: the agriculture industry relies on undocumented laborers. And Nassif—whose organization represents the growers who supply half of the nation’s fresh produce—says the problem his members face isn’t too many illegal immigrant workers, but too few.

“A combination of factors has been building to create what is now clearly a crisis for our members, and for agriculture in general,” Nassif says. “If something is not done immediately to resolve the situation, the agriculture industry will suffer major economic damage. The time to act has now arrived.”

Bob Nielsen, senior vice president for the Salinas-based lettuce-growing giant Tanimura & Antle, agrees that things must change for the future of the industry.

“We’re at a point where we need to talk about the issue and deal with it,” Nielsen says. “Immigration laws have worked, but they don’t work well enough now. Immigration laws, like most laws, respond to situations rather than get in front of the parade.”

While the vast majority of harvests in the Salinas Valley are done for the year, and most fieldworkers have followed seasonal jobs to Arizona and Southern California—where the labor shortage is reportedly worse—local growers and contractors say a lack of field hands is a fast-growing dilemma.

Alfredo Urquidez II, owner of Roberta’s Labor Contractor in Soledad, which supplies workers for growers in Monterey County, says stricter government regulations are putting painful pressure on the ag industry. “It’s exactly like that movie, A Day Without a Mexican,” Urquidez says, referring to the 2003 film mock-umentary in which the nation grinds to a halt when all of the Mexican workers suddenly disappear.

“I’ve lost a lot of people ever since about three years ago, when they started requiring us to prove that the people we hire are legal.”

Despite more stringent hiring rules, Urquidez says, many growers continue to skirt the laws and knowingly hire illegal workers. If they don’t, he says, “then who’s going to do the work?”

On this issue, the United Farmworkers union is standing shoulder to shoulder with the growers.

“For decades growers have complained about labor shortages,” says Marc Grossman, UFW spokesman. “But today, there is merit to what they are saying. We’ve seen it.”

To agricultural leaders and the UFW, the solution is simple: legalize the illegal workers already toiling in the fields—more than 80 percent of whom are Mexican-born—while making it easier for growers to hire foreign workers from abroad.