A 15-year-old Montgomery Village youth characterized by friends as "happy-go-lucky" and well liked, was found drowned yesterday afternoon, his body weighted down with a cinder block, at a public pool near his home.

Montgomery County police called the death of Daryl Nelson an apparent suicide and said they do not suspect foul play. Dr. John G. Ball, county medical examiner, said he cannot rule out homicide until an autopsy is performed.

The youth, a ninth-grade student at Montgomery Village Junior High School, was discovered about 12:15 p.m. by a passerby, lying face up near the 10-foot marker in the Watkins Mill Pool on Club Lake Road, police said.

They said a bicycle tire tube was attached to his belt and to a cinder block and that a pair of scissors was found at the bottom of the pool beneath his body.

Police and neighbors said Daryl, the son of Arthur and Veronica Nelson of 19124 Kindly Ct., had been deeply saddened by the death last week of a grandmother, with whom he had been close. Neighbors said the family was at a loss to explain why the youth might have wanted to take his own life.

Schoolmates said he made "all A's and B's" and was a member of the junior high basketball team and also played baseball and football.

Gladys Magwood, assistant principal at the junior high, said Daryl was "a model student, a very fine boy who never presented any problems.

"He was looking forward to Seneca [High School]. He was always asking me about what kind of courses [it has], about teachers. He was always asking about the football coaches," said Lorraine Loll, who said she often babysat for the boy when he was younger.

Mrs. Loll said the boy's father, a pharmacist, told her his son always took the key to their house to school and then let in his younger sister, Kelly, when she came home from school.

Yesterday, before heading off to school, he gave his little sister the key, Mrs. Loll said.

Several schoolmates said they had not seen Daryl at school yesterday.

Montgomery Village officials said the pool where Daryl was found was not yet open for the season and its gates were locked. Police speculated that he climbed over a fence to reach the pool. Lynn CCracken, a Village employe, said she had checked the pool area around 12:30 p.m. but did not see the body.

As police took the body from the pool, a crowd of youngsters from Daryl's junior high school and the neighborhood gathered and some recognized the dead youth.

One of Daryl's friends went with police to the youth's home and returned with the parents.

As the crowd looked on, Arthur Nelson kneeled over his son, sobbing and caressing his forehead.

Medical examiner Ball said there was a bump on the youth's head that could have been self-inflicted or could have resulted from hitting the side of the pool. He also said there were marks around his neck that could indicate strangulation, but police said they believe those marks were made by a metal stretcher used to remove the youth from the pool.

Ball said results of the autopsy will be ready today. CAPTION: Picture, DARYL NELSON . . . was a model student