A quick turn of the weather forced rangers into rescue mode at Lake Mead National Recreation Area in Nevada and Sleeping Bear Dunes National Lakeshore in Michigan as high winds and waves left dozens of boaters seeking help. The final tally: 70 distress calls at Lake Mead, 11 rescues performed, including of one woman who spent three hours treading water and praying, and the rescue of five young sea kayakers at Sleeping Bear.

At Lake Mead, a sudden thunderstorm churned up 5-foot waves and 8-foot swells on Tuesday, according to a park dispatch. All those in trouble on the lake were said to be rescued, including a woman who found herself treading water for hours.

A woman in her 30s was rescued around 8 p.m. in the middle of the lake after treading water without a life jacket for more than 3 hours. She was on a personal watercraft and decided to take her life jacket off to go swimming just before the storm hit. She was rescued, treated and released. Her husband and stepson were rescued earlier in the evening.

The others who were rescued were wearing life jackets.

“Life jackets and first responders saved lives today,” said Lake Mead spokesperson Christie Vanover. “Visitors did the right thing when the storm came. They put on their life jackets, they moved to shore and they called for help when they needed it."

At Sleeping Bear Dunes National Lakeshore, five teens needed to be rescued from Lake Michigan on June 29 after winds gusting to 25 mph generated waves to 5 feet. The teens were attempting to kayak approximately eight miles from South Manitou Island to the mainland of the park at Glen Haven.  A ranger stationed on South Manitou Island received a phone call from a sailing vessel captain who reported picking up three kayakers who were in jeopardy, the park reported, adding that "two other members of their party were reported missing on the water and had not been seen for two hours."

"Rangers and personnel from Glen Lake Fire Department, Leelanau County Sheriff’s Office and the Coast Guard conducted a search-and-rescue mission in and around park waters. Through joint search efforts, the two missing teens were located approximately one mile off the shore of Glen Haven. One was found in their boat and the other in the water," reported Chief Ranger Phil Akers. "The two were hoisted from the water by a Coast Guard helicopter and transported to emergency personnel at a boat ramp in Glen Arbor. The sailing vessel transported those on board to a waiting ambulance in Leland Harbor.  Due to timely reporting, quick actions of responders and interagency coordination, all five teenagers avoided life-threatening injury and only suffered minor to moderate hypothermia. The water temperature on the surface of the lake was approximately 55 degrees."

While the hot summer temperatures make lake and ocean waters tempting, be sure to catch the latest weather report before heading out, and then keep an eye on the sky.