Earlier this year, rumors flew that the leader of the secretive polygamous sect, self-proclaimed prophet Warren Jeffs, may be planning some kind of Waco-style violent end for the members.

Town members have so far been relieved that the church members are keeping relatively quiet. A local sheriff's deputy told the Associated Press that they seem to be "hardworking folks" and "awesome contractors, great at what they do."

Schleicher County Judge Johnny Griffin told a reporter that "they've done nothing to warrant any kind of great fear." And that any legal action might threaten the members' rights to privacy and religious freedom.

It is perhaps commendable that the people of Eldorado want to be as welcoming as possible to their new neighbors - local clergy have tried to go introduce themselves - and believe that they are entitled to practice whatever religion they like.

But the people of Eldorado should not be lulled into complacence. They have a serious crisis brewing in their back yard. And it would be no sign of bigotry for them to recognize that the newcomers do not represent an opportunity for interfaith dialogue, but rather a danger to themselves and any civil society that surrounds them.

FLDS is one of a few fundamentalist sects that split off from the Church of Jesus Christ of Latter-day Saints in the late 19th century when the federal government forced Mormons to end polygamy. Polygamy, of course, remains illegal in all 50 states, despite the best efforts of polygamist Tom Green, who recently lost a bout in federal court in his suit to overturn Utah's 114-year ban on the practice.

But several polygamous communities, each with a few thousand members, have been allowed to grow in Utah, Colorado and Arizona, among other places.

Polygamy's negative effects on children in these communities are well-documented and truly shocking. We know from firsthand accounts and court cases that child rape, incest, physical abuse, sexual abuse and child marriage often occur within those closed sects.

To keep girls ignorant of the fact that these activities are wrong and illegal, intellectual and physical isolation is necessary. Children are rarely given an education past elementary school, and if girls run away, they are pursued and often beaten if they are caught.

Dorothy Allred Solomon's 2003 autobiography, Predators, Prey and Other Kinfolk, offers a typical account of childhood in one of these communities. Mrs. Solomon describes herself as the "only daughter of my father's fourth plural wife, 28th of 48 children," growing up in an environment in which personal identity was erased and violent behavior was often ignored.

Last year, Allen Rex Harrod, the self-proclaimed prophet of a California polygamous community, was arrested on 97 counts of child molestation. Three adults and one child have accused him of abuses spanning a quarter of a century. One of his wives is accused of observing and photographing some of these acts.

And last year, Mr. Jeffs, the man now coming to Eldorado (who is reported, by the way, to have 60 wives himself), expelled 20 church members and "reassigned" their wives and children to others.

According to the Utah attorney general, there was a power struggle in the community, and some who were expelled provided evidence to the police of child abuse, incest, sexual assault, racketeering and welfare fraud. Three 16-year-old girls fled the community after the expulsion, two of them claiming they were about to be forced into marriages with much older men.

Law enforcement, citing a lack of resources, generally doesn't target "adult consensual bigamy" despite flagrant violation of polygamy laws. Instead, it waits for victims of its associated crimes to surface.

This is apparently the course that the authorities in Eldorado plan to pursue. County Justice of the Peace Jimmy Doyle explained that there is nothing he can do "until one of the girls comes into my office and raises her hand and swears they've been molested by so-and-so."

Acknowledging the problem, he notes, "That's never going to happen."

David Leavitt, the prosecutor in the Tom Green case, agrees that such a course would be fruitless. "These societies are so secretive and the women are so controlled and manipulated from birth that you almost never see victims" coming forward.

Vicky Prunty, head of the Salt Lake City support group Tapestry Against Polygamy, which helps children and women escape polygamous situations, notes that trying to stop these crimes without prosecuting polygamy is "like clipping the leaves without ever getting to the roots."

What is it about polygamy that makes the roots so deep and destructive? Some suggest that the economics of one man trying to provide for so many families inevitably leads to poverty and crime. (Welfare fraud is rampant in polygamous communities, with as much as 50 percent of the population relying on public assistance.)

Others say the jealousy generated by plural marriages corrodes families and individuals. Or that the dissolution of individual identity in such communities simply leads to a lack of respect for other human beings.

Whatever the case, polygamy is not an activity whose effects are restricted to the bedroom and consenting adults. Rather, it seems to corrupt civil society as a whole, destroying education, individual rights and the rule of law - in other words, the foundations of democratic governance. Just as with slavery, to which polygamy was compared in the presidential election of 1856, even a single instance can fundamentally alter a society.

Authorities in other states where polygamous communities exist are now caught in a difficult situation. The sects have been allowed to flourish for so long that prosecuting polygamy has become a logistical nightmare.

As difficult as it is to put a couple of thousand adults in jail, figuring out what to do with all of the children left behind is an almost insurmountable obstacle.

The authorities in Eldorado and the other towns nearby, on the other hand, have the chance to nip this problem in the bud. They need to be clear that polygamy is illegal and will not be tolerated.

—Naomi Schaefer Riley is an adjunct fellow at the Ethics and Public Policy Center and the author of God on the Quad.