A 16-year-old youth, an apparent drowning victim, was found dead in a back yard pool in the Burke area, Fairfax County police reported yesterday.

The youth, whom police did not identify pending notification of relatives, was found floating nude in a pool in the 4700 block of Guinea Road, which is near the youth's home, police said. His clothes and a wallet were lying by the side of the pool, police said.

Owners of the home, whose names were not released, were away on vacation, and the body was found by a house sitter around noon, police said.

Results of an autopsy are expected today. Foul play is not considered likely, police said. add d Drug Charges Against Two Dropped Charges have been dropped against a District firefighter and another man who were arrested last month in an investigation of what authorities said was a multimillion-dollar drug operation nicknamed "dial-a-dope."

A charge of conspiracy to distribute a controlled substance was dismissed against fireman Carlton T. Clemons after a voice analysis proved that he had not telephoned the operation, his lawyer, Barry C. Stiller, said. Charges against Edward W. Lyles Jr. of Washington also were dropped, according to his attorney, Robert M. Werdig. A prosecutor confirmed the dismissals.

Seventeen people were arrested June 5 in a scheme in which a D.C. telephone number was called to order heroin for pick up, authorities said.