BEAVER ISLAND, Mich. -- The beaches are back this year. The road on Iron Ore Bay, which washed out in last winter's storms, has been rebuilt, making it possible to drive a pickup around the island again. The high waters that threatened docks, homes and waterside businesses here and many other places on the Great Lakes have receded.
No one is certain exactly why it has happened, any more than the climatologists and geologists are in agreement on why lake levels rose, year by year for the past decade, well beyond their norms. Every single month in 1986, the height of Lakes Superior, Michigan and Huron was above any recorded in this century.
Now they have gone down, and the relief is universal. Cabin owners who had driven log pilings into their beaches and piled rocks in front of their porches to keep the sand from sliding away from under the foundations are feeling more secure. Other emergency measures are back on the shelf, and life has resumed its normal pleasant pattern.
Foolishly, some say. Consulting geological evidence eons older than the actual 20th century measurements, these scientists argue that we are in the trough of a longer cycle. What we think of -- and calibrate -- as ''normal'' lake levels often have been exceeded in past geological eras, they say, and may well be topped again. Not just a few lakeside cottages but whole cities have been built on land that was under water in past eras.
The beaches -- indeed, the whole island -- we enjoy may be ours only as a temporary indulgence, lasting through several human generations but only a brief moment in geological time.
What is true of our beaches may also be true of our democracy at home and of our power in the world. The other evening, after a hike on the beach, I picked up a copy of a little booklet I had brought here from Washington. Published last month by the Woodrow Wilson International Center for Scholars, a part of the Smithsonian Institution, the slim, 37-page volume with a red, white and blue cover bears the weighty title, ''Lessons From the Fall and Rise of Nations: The Future for America.''
It is the transcript of a discussion held last month at the Wilson Center, where four scholars offered generally gloomy answers to the question, ''Can the United States preserve the position it has occupied in the world during the lifetime of most of us here?'' As Paul M. Kennedy, a Yale historian, said: ''The honest answer to this question must be no, simply because it has not been given to any one society to remain permanently ahead of all the others.''
Such a topic invites pomposity, and there were many examples in the roundtable discussion among a dozen or so guests which followed the opening statements. But there were also some striking comments.
One came from James H. Billington, who has been the director of the Wilson Center and has been nominated as the new librarian of Congress. A noted historian himself, Billington said he appreciates the historical reasons for skepticism about the duration of America's preeminence, but ''I feel that the objective assets that still exist in this country, including the moral ones of the people, are very substantial.''
''It's our market that everybody wants into,'' Billington said. ''What's more, this nation has the values that everyone else wants. Our kind of functioning democracy, our ability to deal with ethnic, religious, ideological plurality . . . this is what . . . a lot of countries are groping for . . . what they would like to achieve.''
Then he added something which I can strongly endorse on the basis of the interviewing and door-knocking I have done with voters across this country in the past year: ''I think the American people as a whole are much stronger, more resilient and more capable of fresh creative effort than the leadership they're getting. And by that, I don't mean just political leadership.''
Billington talked about the ''erosion of values'' in America's elites, citing such examples as the aversion of the graduates of leading universities to serve in the armed forces and the eagerness of business leaders to secure their own financial futures whatever the productivity of their companies.
If the United States forsakes its heritage and squanders the opportunities it has been given, it will not be because of some historical predestination, Billington said, but because we have too many privileged people ''who prefer to be overpaid, have two long vacations a year, hire a mercenary army to defend them, work themselves up over symbolic political issues and neglect the real needs of their own nation.''
Thinking about that on my next beach walk, I concluded that my neighbors had not been foolish to drive pilings and pile rocks to save their homes, just because the water may cover the island in some future century. The legacy we inherited is worth struggling to preserve.
We cannot control the lake level -- or even predict it -- but we can take responsibility for our lives and for our nation. And we must.