A family boating trip on Jackson Lake in Grand Teton National Park nearly had a tragic ending earlier this week. Prompt emergency care saved the day, and the situation can serve as a reminder for others as the peak summer boating season begins.

According to a park report,

Two nine-year-old girls from Jackson, Wyoming families suffered carbon-monoxide poisoning while “teak surfing” behind an inboard ski boat on Jackson Lake on Tuesday afternoon, June 30. Teton Interagency Dispatch Center received a 911 call regarding the situation about 4:30 p.m. and park emergency medical providers, along with numerous park personnel from other divisions, responded immediately to the Colter Bay Marina to provide life-saving medical care before transporting the young girls to St. John’s Medical Center. After receiving highly concentrated oxygen treatment, the girls were revived and later released from the hospital.

A family of four (mom, dad, son and daughter), along with a young girl and her brother from another family, were out for an afternoon excursion on the lake. The young girls, and their older brothers, were taking turns holding onto a swim platform attached to the back of a 20-foot, 1994 Tige ski boat while being pulled across the water.

Because of the close proximity to the boat’s exhaust ports, the two girls and one of the boys were subjected to a high concentration of carbon-monoxide gas. When both girls lost consciousness and slumped down behind the platform, one of the brothers realized something was wrong and quickly pulled them out of the water and onto the platform. The young man also made an emergency call for help on his cell phone.

Although the father was operating the ski boat when the girls lost consciousness, his son took over in order to drive to the marina to get emergency care. During this time, the father gave CPR to one of the girls.

An investigation is underway regarding the circumstances of this incident and a citation for operating a vessel while allowing a person to hang onto a swim platform will likely be issued, as well as a citation for failure to provide required personal floatation devices for all boat occupants. Because of its inherently unsafe nature, “teak surfing” is illegal in all national park units—including Grand Teton; it is also illegal in a number of states.

The activity is called “teak surfing” because the swim platforms on boats are often made of teak wood. Swimmers use these transom platforms to body surf on the wake behind a slow moving boat; however the inboard-motor exhaust ports place the swimmers in direct contact with carbon-monoxide gases, leading to potentially deadly exposure. High concentrations of carbon monoxide can cause a rapid loss of consciousness and death.

Levels of carbon-monoxide are more dangerous in the boating environment because they can lead to drowning. In addition, carbon-monoxide concentrations released from boats can be over 150 times higher than exhaust from an ordinary automobile.

Carbon monoxide—an odorless, colorless, and tasteless gas—is a leading cause of accidental poisoning deaths each year in the United States. According to the Centers for Disease Control, approximately 500 people perish annually due to carbon-monoxide poisoning. Symptoms of carbon-monoxide poisoning may include severe headache, dizziness, confusion, nausea, fainting, and death. Low levels can cause shortness of breath, slight nausea, and a mild headache.

“This incident serves as a harsh lesson that a seemingly innocent activity can actually be quite dangerous,” said Superintendent Mary Gibson Scott. “We are so relieved that these two young ladies were revived, and that this incident had a positive ending for the families involved.”

Carbon monoxide poisoning during boating trips has been a problem at several other parks, including Lake Mead and Glen Canyon National Recreation Areas. Perhaps this latest incident will serve as a reminder to other boaters about this hazard.