MOAB, Utah -- Two people have died during separate hiking trips in the rugged southern Utah desert country, one a participant in a wilderness survival course and the other a teenager who got separated from her group in 110-degree heat, officials said.

Another hiker died of apparent heat exhaustion and dehydration in South Dakota's Badlands National Park, the park's chief ranger said.

Dave Buschow, 29, of River Vale, N.J., died Monday night near Boulder, Utah, while taking part in a 28-day survival course offered by the Boulder Outdoor Survival School, Garfield County spokeswoman Becki Bronson said.

Buschow was on the second day of the $3,000 course and in a group of 12 with three staff members. The group was resting near a water source when one of the students noticed Buschow was unusually quiet, Bronson said.

"All day Monday they were hiking in the heat with very little food or water," Bronson said. "He was complaining about lack of water and cramping and still given very little water, and it was still hot."

Temperatures were in the low 90s in the area, the National Weather Service said.

Bronson said students are intentionally given little food or water to simulate hardship conditions in the course, designed to teach primitive survival skills using limited tools.

School representatives did not immediately return a call seeking comment.

The school's Web site says its field courses teach participants how to survive in wilderness with minimal food, water, clothing and gear. "Our goal is to take you from a world of convenience and comfort and put you in a situation where you must go 'just a little bit farther' - past those false limits your mind has set for your body," the site says.

On Sunday, Elisa D. Santry, 16, of South Boston, Mass., died on the 16th day of a three-week Outward Bound Wilderness course near Canyonlands National Park. The temperature was about 110, said San Juan County Sheriff Mike Lacy.

Organizers said the girl was with five other teens, ages 16 to 18, hiking through heavy brush to reach rafts waiting for them at the Colorado River.

As they were nearing the river, she had lagged behind, possibly to wait for another hiker, the sheriff's office said Tuesday. The other hiker reached the river but Santry did not show up. She was later found up a small side canyon, the sheriff's office said.

"There was no evidence of foul play," said Mickey Freeman, president of Outward Bound Wilderness. An autopsy was planned.

The girl had passed a medical screening before joining the program, the group said. Outward Bound canceled the remaining five days of the program, which included hiking, climbing and rafting. There were 13 other teens participating.

Canyonlands National Park is about 200 miles southeast of Salt Lake City, and Boulder is about 200 miles south of the city.

In southwestern South Dakota, a woman hiking on a short but steep Badlands trail died Sunday, when the temperature was well over 100 degrees.

Other hikers found the body of Joan Kovach, 52, of Canfield, Ohio, Chief Ranger Mark Gorman said.

"Where she eventually gave in, her water bottles were empty and unfortunately she just did not have enough water for the conditions," Gorman said. He said people hiking in the park during extreme heat should carry at least a gallon of water.