Riding a personal watercraft on a Sunday in July between noon and 6 p.m. may be hazardous to your health, according to statistics released last week by the Maryland Natural Resources Police.

There were 215 boating accidents in Maryland in 1998, resulting in 11 deaths and 121 injuries, according to the Natural Resources Police. One-fifth of those accidents, 43, took place in Anne Arundel, the most of any county in the state. DNR officials said congestion on the Severn and the South rivers is partly to blame.

Southern Maryland's three counties had some of the lowest accident numbers last year, with Calvert reporting eight boating accidents, Charles nine and St. Mary's four.

Police said personal watercraft were involved in more accidents (91) than any other type of vessel. More accidents took place on Sunday (68) than any other day, and the majority of accidents took place in the afternoon. July had more accidents than any other month.

Those statistics highlight the need for more public education about boating and water safety, particularly for personal watercraft users, according to the Natural Resources Police, the Coast Guard and boating safety groups.

While the number of accidents, fatalities and injuries on Maryland waters has fluctuated in recent years, the long-term trend seems to be positive.

The 11 fatalities in 1998 were nearly double the six recorded in 1997 but nearly two-thirds less than the 31 boating deaths reported in 1991. Last year's 121 injuries were up 50 percent from the 80 that occurred in 1995, but were substantially less than the annual average of 157 injuries reported from 1991 to 1993.

Richard McIntire, spokesman for DNR, credited safety education and tighter enforcement of the state's Operating While Intoxicated law for the overall decline, but he cautioned against complacency. He noted that there already have been four fatal boating accidents in Maryland waters this year, "an alarming trend."

The Coast Guard and the state maritime police have been paying special attention to users of personal watercraft, often known by their brand names of Jet-Ski or Sea-Doo. Research by the Natural Resources Police has found that up to 90 percent of personal watercraft users had no formal boating training.

"You've got to learn how to handle them safely," McIntire said.

The Natural Resources Police and the Bombardier Motor Corp., a leading manufacturer of personal watercraft, have developed a water safety campaign that includes a short video and an 11-question quiz.

More traffic on Maryland waterways also creates greater opportunities for accidents, said Lt. Todd Offut, supervisor of safety and security for the U.S. Coast Guard in the Port of Baltimore area.

"In the past 2 1/2 years, we've had a 9.6 percent increase in the number of organized marine events on the waterways we cover," increasing the potential for accidents, he said.

"The key is wearing a personal flotation device," McIntire said. "It's that simple." Six of the 11 victims in last year's fatal accidents were not wearing life jackets, he said.

"Even if you're not the captain of the boat, passengers should get some safety education," he said, citing several incidents in which passengers had to assume the helm of lost or endangered vessels.

Also, boaters always should file a boating plan with their marina and bring a radio or cellular phone for emergency communications.

"You never know what's going to happen. The way to be prepared is to be educated," McIntire said.