However, Harris, who provides Utah data to the Coast Guard, warns that apparent drop may come largely because of a change in what accidents are reported.

Halfway through that period, the Coast Guard changed from requiring reports on accidents with more than $500 in property damage to reporting only those with $2,000 or more in damage.

"So all of a sudden, we didn't have to report as many," he said.

Where accidents occur

Lake Powell records almost as many serious boating accidents as all other Utah lakes and rivers combined. Mayer and Harris say it also may have twice the number of boaters as all other lakes combined.

Of the 1,237 reported serious Utah accidents during the decade, 573 (46 percent) occurred in the Utah portion of Lake Powell.

That was more than six times as many as second-place Bear Lake's 90 accidents. It was followed in order by Willard Bay (75 accidents), Utah Lake (58), Pineview and Flaming Gorge (tied at 49), Deer Creek (40), Jordanelle (39), Quail Creek (34) and East Canyon (32).

Overall, 41 Utah lakes and rivers reported at least one serious boating accident. The state had 81 boat-accident fatalities during the period (from drownings, trauma, carbon monoxide and other causes), and 646 injuries that were serious but not fatal.

Lake Powell's overall total of serious accidents (788, including those occurring on its Arizona portion) was enough to place it sixth for accidents among national bodies of water.

Mike Mayer, chief ranger at Glen Canyon National Recreation Area, which includes Lake Powell and surrounding territory, wonders if that is a statistical anomaly, too.

"Glen Canyon takes safety very seriously, so we record everything — every accident," he said. "Areas that don't do a good job of reporting may show a skewed safety record," he said.

But he says the lake can indeed sometimes be tricky for unwary boaters.

For example, boaters in side canyons may enjoy relatively calm water and weather only to find storms and very rough water when they exit into the main channel. "That happened to a kayaker who died this year. She hit rough water in the main channel and tipped over. The water was cold, and hypothermia got to her before she could get to shore," Mayer said.

Also, he warned, "Lake Powell is a reservoir, and the water level and the condition of the lake itself can change literally overnight." Quickly rising water can hide rocks that had poked out of the water previously. To avoid that problem, he said boaters not familiar with the lake should stay in deep, clearly marked main channels.