ALL MARYLAND IS divided among three watersheds, though you might not know it given the attention to the Chesapeake Bay, whose drainage basin includes most of the state, and most of our environmental attention.
A lesser-known one is the Gulf of Mexico, whose drainage extends to the westward-sloping sliver of Garrett County between Backbone Mountain and West Virginia.
The gulf's problems may be greater than the Chesapeake's, with a "dead zone" of low-oxygen water that some years covers thousands of square miles. But this stems more from Midwestern farm pollution than anything trickling from Oakland, Friendsville or Sang Run.
In the state's easternmost watershed, however, the problems are home-grown. These are the coastal bays of Worcester County: Assawoman, Isle of Wight, Sinepuxent and Chincoteague.
Compared with the Chesapeake's 41 million-acre basin, their watershed is small -- 112,000 acres, bounded by Ocean City and Assateague Island on the east and roughly by U.S. 113 and Route 12 on the west.
Similarly, the coastal bays are surrounded by about 22,000 people, compared with the 15 million or so in the Chesapeake's six-state watershed.
But in another respect, they are the bigger bay's equal.
In 1993, state and federal agencies sampled 200 sites throughout the coastal bays, from Rehoboth and Indian River bays in Delaware to the Virginia portion of Chincoteague Bay.
Overall, "the coastal bays were found to be as degraded as the Chesapeake Bay or Delaware Bay," the scientists concluded.
The diversity, abundance and kinds of bottom-dwelling organisms, or benthos, are an excellent indicator of health in such extremely shallow waters. Their average depth is about 4 feet, compared with around 21 feet in the Chesapeake.
More than a quarter of the bays' bottoms showed significant degradation; and more than 75 percent of the bays' water quality was too poor to support the submerged grasses that are so critical to huge varieties of fish and birds.
Not surprisingly, the worst conditions were found to the north, in Delaware, where the drainage includes the most acres that have been developed, the most farmland and the most poultry (therefore manure).
Conversely, Chincoteague Bay, with less human and farm animal pollution, was the cleanest. The bays of the Ocean City area were somewhere between.
