One Saturday morning, as Wendy Fournier sat in her living room drinking coffee, she thought the house sounded awfully quiet. She got up to look around and found her daughter, Aly, was gone.

Aly, now 15, has autism spectrum disorder (ASD), and wandering was something she sometimes liked to do. That's not unusual: Nearly half of people with the disorder, which hampers social interaction and communication, have a habit of wandering.

Such wandering can be fatal, says Fournier, president of the National Autism Association. From 2011 through 2014, she says, her association received reports of 65 people with autism who were found dead after they wandered off. More than 90 percent of them were killed in accidental drownings. "We want to do all we can to prevent these incidents from happening in the first place," she says.

With one in 68 U.S. children now diagnosed with ASD, many parents are coping with the stress of children wandering off. Here are four steps you can take to help prevent wandering.

Identify the triggers. "Wandering is typically a form of communication," Fournier says. "The child is trying to get to something or away from something."

Sometimes children wander off slowly, other times they may ''bolt," she says. In the case of bolting, ''a lot of times it is [triggered by] something going on in the environment where they are so bothered they need to get away. It could be as simple as noise in the room." With enough observation, you will begin to notice what triggers your child to wander or bolt, Fournier says.

Experts aren't sure why water seems to hold such an attraction when children with autism wander. It could be as simple, Fournier says, as the child liking the sparkly look of the water, even if she does not generally enjoy swimming. Or it could be seen as a peaceful place to block out unwanted stimuli. Since water is so tempting, swimming lessons for your child are a must, Fournier says.

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Other children may make a habit of wandering to a favorite park or restaurant, Fournier says. Scheduling regular, supervised visits to those places may help, she says.

Secure your home. Besides the obvious door and window locks, consider inexpensive door chimes. When your child goes out, you'll be alerted, Fournier says.

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Be sure your child wears ID. Get an ID bracelet for your child, with all the pertinent information about name, address, condition and emergency numbers listed, Fournier says. If your child balks at wearing a bracelet,  you can opt for a shoe tag ID. (The National Autism Association offers shoe tags and other safety supplies free of charge on a first-come, first-served basis.)

Let neighbors, teachers and police in on the problem. Complete a first responder’s form and distribute it to neighbors, family and co-workers. It should include your child's name, a photo, physical characteristics, a few pieces of personal information about the child such as his favorite song, information about his verbal abilities and emergency names and numbers.

Let your nearby neighbors know your child has a wandering habit, Fournier says, and encourage them to call you when they see your child, or better yet, to intercept him.

When you meet your child's teacher, be sure the individualized educational plan (IEP) includes notes about the wandering habit.

Talk to your local police department and let them know about your child's wandering probblem. This visit also communicates to your local law enforcement agency that you are a concerned, caring parent, Fournier says. Too often, when children wander despite vigilant parents, others may incorrectly blame the incident on lack of supervision.

For additional steps to reduce wandering risks, check out these tips from Autism Safety.org.

Kathleen Doheny is a Los Angeles journalist specializing in health, behavior and fitness topics.