Hains Point, the "back yard" for generations of Washington families who grill hamburgers, relax in the sun and let the kids run barefoot on the broad grass lawns, has become a magnet for young people, some of whom are bringing illicit drugs with them, according to U.S. Park Police.

"Hains Point is the 14th and U streets of the parks," said Lt. Hugh Irwin, referring to one of Washington's notorious heroin markets. "Except down here, you can buy anything. We have all the drugs here."

Once the balance started to shift away from the family, the use and sale of a raft of drugs -- heroin, cocaine, PCP and marijuana -- started surfacing, park police said.

A special plainclothes drug unit, called the Tactical Crime Patrol, was created in 1983 to combat the problem, Park Police officials said. Last year, the unit reported 215 drug cases, which often represent multiple arrests, at Hains Point.

So far this year the eight-member unit, which covers two dozen other federal parks, has reported 92 drug-related cases at the 90-year-old park, also known as East Potomac Park.

Hains Point, a crescent-shaped peninsula located between the Potomac River and the Washington Channel, has a golf course, tennis courts, a swimming pool, a children's playground and extensive picnic areas in the 327-acre federal park. Park police records show that most of the drug arrests have occurred at the tip of Hains Point near the playground area.

Irwin, a 14-year veteran who heads the drug unit, said Hains Point has been specially targeted this summer. "The parks belong to everybody and families shouldn't be made to feel uncomfortable by loud radios and dope. It bothers me that they don't feel safe here, that they don't feel they belong here.

"They are indeed safe," he said. "I think these park areas are very safe, it's the comfort factor."

Park police report that drug trafficking occurs in most federal parks in the Washington area, but said they consider the problem most serious at Hains Point because of its tremendous popularity and proximity to most of the major monuments.

The possession and occasional use of guns present yet another problem, Park Police said. The vice unit lists one gun seizure at the park in 1984 and four so far this year.

The changing makeup of the Hains Point crowd concerns park police officials.

Lt. Charles Hume, an official assigned to Hains Point, said "Families have a good effect on the parks. If we lose the families, we are in trouble. It's easier to deal with families. They don't want to get arrested and they are less likely to use drugs and alcohol."

One recent weekend the playground parking lot, which has 88 spaces, was filled with about 200 cars. The etiquette for the double- and triple-parkers was simply to announce where the driver would be in case someone needed to get out.

Proud owners of Datsun Zs and Corvettes polished and repolished their spotless cars while radios poured out a cacophony of rap, funk and go-go.

At a picnic table near the Potomac River, the Henson family from suburban Maryland ate chicken salad sandwiches.

"This is our first visit here," said Ed Hanson, 35. "We came to see the Awakening a sculpture at the park and have lunch. But this is not a family place. With the age group you have here, you get drugs. I wouldn't stay here after dark with the family."

Shortly after the Hanson family left, three young women and a man sat down at the same table. Minutes later, members of Irwin's drug squad jumped out of an unmarked squad car and arrested all four for allegedly possessing PCP.

Bill Askew, 25, watching the arrests from the parking lot, called the drug situation at the park last summer "outrageous."

"In the daytime there were quite a few drugs and after the sun went down, it was all drugs," he said.

Among the dozens of car polishers in the lot was Carlos Fortune, 24, who polished his sports car as he kept one eye on a group of women walking by.

"I come here to meet with other Z owners, catch the cool breeze and for the atmosphere," said Fortune. "There is never a dull moment. But I've noticed a change here. There is more security, more cops." Fortune also said that he thought the drug situation had escalated from last summer and now "it is out of hand."

Dave Rowland, 21, of Fort Washington, said Hains Point is known for drugs well beyond Washington. "Hains Point, Hains Point, everyone says they are going to Hains Point. People who want to, come here to do drugs. But then drugs are everywhere. Hains Point is predominantly black and Fort Washington park is predominantly white and there are drugs there also."

Debra Hairston, 32 of Oxon Hill, pulled together two picnic tables to make space for her four children plus three other children to have a picnic lunch.

Hairston, a woman with a quick smile and a gentle hand for children, was not happy about the changing crowd at the park.

"I am a Washingtonian and my family used to bring me here but I won't come back anymore because of the young people," said Hairston. "This is not a park, it is a singles place."

Capt. William Spruill, commander of the central district, which includes Hains Point, said, "As the families and kids leave, the pressure gets more intense on the officers. Drugs, loud music and young people become their concerns.

"Parks provide an atmosphere for anyone into distributing drugs because there are a lot of people. The drug dealer can maneuver among the people, not like on the streets where police can scrutinize his every move. Drug people know kids will experiment with drugs. The park provides a haven for drug dealers," he said.