November 30, 1986

Bay Street Landing, a 40-acre waterfront community of co-ops and condos in St. George, S.I., has just received its first commercial tenant, a restaurant called Shanghai Red's. ''The weak part of the development was the retail, and that's why the lease is so important to us,'' said Christopher M. Jeffries, who, with the General Atlantic Realty Corporation, is overseeing the completion of the project, which will have 1,000 apartments by 1990.

BECAUSE the state should help troubled adolescents cut through the social services bureaucracy by offering health care in high schools, says the Commissioner of Human Services, school-based clinics will be a priority for his administration. ''Our fragmented, scattered, very narrow categorical programs, with a different agency for every problem, have not done a good job of reaching troubled teen-agers,'' said the Commissioner, Dr. Drew Altman, in a recent interview in his office here. ''Schools represent the place where you can reach the majority of teen-agers, but not all of them. So the strategy is one of supporting community-based organizations and asking the schools to provide space and become part of the program.'' According to Dr. Altman, services offered by health-care clinics outside New Jersey depend on community needs and include drug and alcohol counseling, family planning, day care, psychological, academic and vocational counseling and job placement.

A look at the show of recent acquisitions at the Pierpont Morgan Library has convinced this visitor that the library has to be one of the best places in which to be walled up alive. (A set of pass keys would help, of course.) There would be books to read, drawings to look at, and music to hum in one's head for a long lifetime. It would be a good idea to know a dozen languages, living or dead, but you'd always have the dictionaries to hand. It would help to know that Claude Gillot was one of Watteau's teachers and that the great French 18th century connoisseur and collector Pierre-Jean Mariette liked to lay down his drawings on mounts that were colored a particularly sumptuous blue. Both these esoteric facts are relevant to the present exhibition, where Gillot makes a great impression and Mariette's mounts look gorgeous, but you could have a very good time without knowing either of those things.

RONALD Reagan reached the nadir of his Presdency last week. There is no dispute, in Washington or elsewhere, about that. The questions preoccupying politicians and diplomats now are whether things could get even worse and, if not, how fast and how far the President will come back from a crisis that has raised doubts about his judgment, his leadership and his credibility. Upon the answer to those questions may depend the President's ability to continue leading the Western alliance, his capacity to counter the mischief-making in which many analysts here believe the Soviet Union may be tempted to indulge, his ability to negotiate with a Democratic-controlled Congress on such subjects as the budget deficit and further aid to anti-Communists in Central America and his chance of influencing the choice of a successor - indeed, his place in history.

Vice President Bush, who has been all but invisible to the public since the crisis over arm shipments to Iran erupted, intends to make a public statement on the situation soon, perhaps next week, according to friends and associates. ''He is not trying to distance himself from the President,'' one friend said today. ''It would be a very serious error to avoid comment altogether, but it is only prudent to wait for a bit while the situation resolves itself. Whatever he says will not only attract a lot of attention now, it will be remembered all through 1988.''