Environment: Return of the Grebe

Clear Lake, Calif., is a shallow, 40,000-acre body of fresh water that lies about 100 miles north of San Francisco. For centuries, it was home for a large colony of Western grebes, lovely birds that swim with the stately grace of swans and dive as skillfully as loons. But 15 years ago, in an environmental tragedy unwittingly perpetrated by man, large numbers of grebes began dying off, and the once-clear waters of the lake turned murky and green. Now, by introducing a new ecological cycle, scientists have saved Clear Lake's grebes and even clarified...