And Aramark, which also provides most other services at the lake, bought as many as 1,000 household carbon monoxide alarms and installed them in houseboats, though the alarms were not intended for marine use, documents say.
Investigators from the National Park Service and the U.S. Coast Guard discovered the design and alarm issues after the June death of Glenn Howeth, 62, of Winslow, Ariz.
Howeth and seven family members were aboard a houseboat, rented from Aramark and tied in a bay on the Utah side of Lake Powell, when they began experiencing symptoms of carbon monoxide poisoning. Howeth suffered a heart attack, believed to have been induced by the poisoning, while carbon monoxide sickened the others.
Park Service reports say rangers do not know how carbon monoxide entered the boat -- that someone may have left open a window or the high concentration of gases may have simply penetrated the boat.
But the source of the carbon monoxide was the exhaust system on the boat's generator, according to the Park Service and Coast Guard.
The four-cylinder, gasoline-powered generators on houseboats suck lake water to cool their motors. On the Howeth boat, water flowed from the motor compartment to a separator, which kept it in one compartment and sent fuel exhaust to another. The water spewed out through a submerged drain between the pontoons, while the exhaust was supposed to be blown out a stack above the boat.
But investigators for the Park Service and the Coast Guard found the boat's exhaust line was too long and had too many bends, which created resistance and prevented exhaust from escaping through the stack. Instead, according to federal documents, the exhaust was expelled through the water drain beneath the cabin.
When park service rangers investigating the Howeth poisonings started the houseboat's generator, according to documents, they "heard a loud bubbling" in the water under the boat.
"It was obvious the generators's exhaust system was malfunctioning and causing carbon monoxide gas to be discharged into the tunnel area beneath [the] bow deck between the pontoons," a Park Service report says.
Park service rangers were later told Aramark mechanics were testing other Lake Powell houseboats with similar exhaust systems. A ranger reported the mechanics were finding exhaust venting out those water drains, too, and a hazardous level of more than 600 parts per million of carbon monoxide was accumulating under the boats.
The Salt Lake Tribune obtained the reports and others related to the Howeth case in requests under the Freedom Of Information Act.
The 75-foot houseboat rented by the Howeths was manufactured in 2006 by Twin Anchors of British Columbia. A Coast Guard report said Twin Anchors installed the exhaust system without consulting the company who manufactured the parts.
In an interview Wednesday, James A. Riddle, an attorney for Twin Anchors, said his clients do not yet concur with the findings of the Park Service and Coast Guard.
"We have not concluded there was a malfunction in any way," Riddle said.
Riddle said more investigation is needed and may lead to different conclusions. Riddle said he did not know if exhaust systems like the one aboard the Howeth boat were installed on houseboats elsewhere in the United States and Canada.
The Coast Guard recommended changes to the generators' exhaust systems: removing the slack from the exhaust lines, placing the water drain outside the pontoons so any gas could more easily dissipate and adding ventilation from the generator compartment to the outside.
A separate park service report from mid-July said Aramark would follow the suggestions to eliminate exhaust escaping through the drain. About 50 boats had exhaust systems similar to the Howeth boat, according to documents, and Aramark planned to alter the systems as replacement parts arrived and renters returned the houseboats to the docks.
Aramark did the right thing by changing the designs and deserves credit, said Kiko Villalon, a boating consultant who investigates accidents for the Coast Guard and wrote one of the reports on the Howeth poisonings.
"Leaving it like it was could have put other lives in jeopardy," Villalon said in an interview.
Then on Oct. 1, a representative affiliated with carbon monoxide alarm manufacturer Pro-Tech-Safety called the park service, pointing out its alarms were designed for residential use. The park service report said Aramark bought as many as 1,000 Pro-Tech model carbon monoxide alarms, identical to an alarm found on the Howeth boat, for use at Lake Powell, but the alarms are intended "ordinary indoor locations of family living units."
An attached user manual for the Pro-Tech alarms refers only to use in residences. Marine certified carbon monoxide alarms, which are similar to residential alarms but are water tight and resistant to vibration, were found elsewhere in the Howeth's boat.
None of the carbon monoxide alarms sounded the night the family was poisoned, according to witnesses and audio recordings.
Phil Cappel, chief of the Coast Guard's recreational boating product assurance branch, said a marine-certified alarm may not have been necessary on the interior of a houseboat, where an alarm would not be exposed to the splashing or bouncing common to other boats.