Christopher Alan Carlson, 45, already has served nearly 10 months in prison and could be eligible for early release, so he may only have to be in prison for another 11 months.
U.S. District Judge Frederick Martone said the fact that Carlson obviously cares very much for his grandchildren and that he has struggled with attention-deficit disorder and hyperactivity his whole life helped him conclude that Carlson deserved the lighter sentence. He could have been ordered imprisoned for up to 17 years.
Carlson told the court that he would never hurt his grandchildren and that he just wanted to show them the beauty of the Grand Canyon.
"I love my grandchildren greatly," said Carlson, who was shackled at the hands and ankles and wore a black-and-white prison uniform. "I wanted to afford these children a beautiful opportunity at a young age to experience something magnificent."
Carlson is such a young grandfather because he had his first child - Tara Danaher, the mother of the boys - when he was 15. Danaher was 17 when her oldest was born. In all, Carlson has five children, all with different mothers.
Shortly after his arrest in August, Carlson told investigators that his grandsons were overweight and that he thought hiking the Grand Canyon would get them into shape. They were 8, 9 and 12 at the time.
The boys are now living with their grandmother in Indiana.
The boys have said that they love their grandfather and loved spending last summer traveling to various countries with him. But the boys also testified that Carlson kicked or hit them if they were too slow on a 15-mile hike on Aug. 15 and a 19-mile hike on Aug. 28.
The oldest boy told jurors that he secretly asked a hiker to call 911 toward the end of the Aug. 28 hike after he began throwing up, fell down because of cramping and experienced changes to his vision.
"I needed medical attention and I was hurting and he was hitting and pushing me and calling me fat," said the boy. "I was scared and it was hard and I was all weak and tired and kind of hurt."
A ranger with binoculars spotted the group during the Aug. 28 hike, the same day a man died on another trail from heat exposure. The ranger reported seeing Carlson shoving the oldest boy and whipping him with a rolled-up T-shirt.
Rangers fed the boys and gave them water after one showed symptoms of heat stroke and the other two had signs of heat exhaustion and dehydration.
During trial, defense attorney Jeffrey Williams portrayed Carlson as an active health nut who had a firm hand and wanted to show the boys the world. Like anyone after a long hike, the boys were tired, hungry and thirsty, but Carlson only allowed the boys to eat healthy food like tofu, hummus and veggie burgers, Williams said.
Prosecutors told jurors that Carlson deprived the boys of food and water during the hikes. The boys reported that they did get some water, but not always enough, and ate celery and other snacks during the hike.
Prosecutors also said that the middle child got severe blisters on the first hike and that they hadn't fully healed by the second hike. They showed jurors photos of the blisters, which turned into bleeding ulcers, and prevented the boy from wearing shoes for weeks.
On Thursday, prosecutor Dyanne Greer said that no one was disputing that Carlson loved his grandchildren and that they loved him back.
"(But) love and abuse are not independent of each other, unfortunately," she said. "In this case, these children were placed in the position that no child should ever be placed in. These children were hurting and this defendant did nothing to stop it. He kept them going even though he'd been told this was a 19-mile hike in 108 degrees with inadequate food and inadequate water."
Carlson said that it was only hot at the bottom of the canyon, and that it was in the 70s toward the top.
A jury found Carlson guilty of three counts of child abuse stemming from the Aug. 28 hike, but not guilty of any abuse on the Aug. 15 hike.
On top of the prison time, Martone ordered that Carlson undergo a psychological evaluation, be put on one year of supervised release after he's out of prison and undergo parenting classes.
He also recommended that Carlson serve out the rest of his prison term in Indiana so he could be close to family.
Martone told Carlson that it was clear from their testimony during trial that his three grandsons were intelligent and good kids.
"I think any grandfather would be proud to have any one of them," he said. "It's amazing - they walked into this courtroom and testified about such difficult things with both earnestness and sincerity, and on occasion good humor. So whatever we do here today, you should take that to the bank that you've got three great grandkids."