Former professional Bruce Slattery of Lakewood avoided three-putting on Bethesda Country Club's hard and fast greens and shot even-par 70 for a three-shot lead after the first round of the 72-hole Middle Atlantic Golf Association's men's championships yesterday. Only 10 golfers in the field of 149 scored 75 or better.

Slattery bogeyed the par-4 final hole after what he thought was a perfect tee shot wound up under a pine tree.

"I thought 69 would probably tie for the lead," said Slattery, 23, club champion at Lakewood. "I knew the course was playing difficult, but I didn't think 70 would be way in the lead."

Slattery made three birdies and three bogeys, and was followed by Bill Lawler of Exeter, Pa., 73; and Britt Stenson of the host club, Larry Zee of East Autora, N.Y., and Peter Jacobi of Army Navy, all at 74.

Four-time winner Marty West of Columbia Country Club took a quadruple-bogey 8 on the fourth hole, where he drove into woods and four-putted. West, who had trouble with his putter until midway through the back nine, finished with 78.

Earl Johnson of Army Navy made a hole in one on the 163-yard 13th using a five-iron. He finished at 79.