U.S. Attorney Elsie L. Munsell yesterday asked for a federal court order that would force anyone arrested entering the Potomac River from park land to appear in court.

Although the maximum penalty for the offense is a $500 fine and six months in jail, it is now treated much like a parking violation and people who choose not to contest the charge can pay a $25 fine by mail.

The order Munsell is seeking from the eight active U.S. District Court judges in the Eastern District of Virginia is designed to discourage swimmers from plunging into the particularly treacherous stretch of the Potomac from just above Great Falls to Chain Bridge.

"This is an offense that risks serious injury or death," Munsell said after filing the motion. "We are hoping this will help people see how dangerous it is."

J. Frederick Motz, the U.S. attorney for Maryland, said that later this week he will file a request similar to Munsell's for an order that would affect people who enter the river from the Maryland side.

Last year, at least 14 people drowned in the 11-mile stretch of river between Seneca and Chain Bridge. There have been five reported deaths so far this year. An average of seven people die annually in the waters that even experienced canoeists frequently describe as violent.

The river near Great Falls claimed its latest victim two weeks ago when Hai Van Huynh, a 19-year-old junior at Arlington's Wakefield High School.

The proposed tightening of the law was hailed by National Park Service officials, who for years have struggled to prevent the summertime Potomac drownings.

"We have tried everything," said Sandra Alley, a spokesman for the Park Service, "signs, patrols, education. But some people just don't care. Maybe this will help."

Despite ominous warning signs scattered throughout Great Falls Park, many people among the thousands who visit the park each weekend go there to leap the rocks and risk a dip in the water.

A spokesman for the Park Service said yesterday he did not know how many tickets have been issued during the past two years, but that the number, along with the frequency of rescues, has increased steadily.

In April, Reps. Frank R. Wolf (R-Va.) and Michael Barnes (D-Md.) urged Interior Secretary Donald P. Hodel to impose automatic $200 fines on those who enter the river illegally from national parkland.

Wolf said yesterday he thinks the move by Munsell "is a significant step in the right direction. The river looks calm but it is very dangerous and this is not to be treated like some minor violation. I strongly support it."

A $3.5 million plan to modify the Potomac's Little Falls Dam two miles upstream from Chain Bridge, known as "the drowning machine" because of the frequency of deaths in its swirling waters, has been approved by the Army Corps of Engineers and the District.

The dam's hydraulic characteristics will be altered by adding grout-filled bags.

Munsell said that U.S. District Judge Albert V. Bryan Jr. in Alexandria had agreed to circulate her request to the seven other judges.