Phillips couldn't see farther than 6 inches in water that is usually clear to 3 feet.

Phillips, a bay coordinator for the U.S. Geological Survey, knew Isabel had knocked soil from the bay's shores, further clouding water made murky from a year of above-average rainfall.

The soil now churning in the bay will sink, Phillips said, and may bury species such as underwater grasses and oysters.

"I think we're going to see the effects from this for years," Phillips said.

A quick boat tour near Whitehall Creek confirmed Phillips' impression. The Tuesday afternoon tour, organized by the Chesapeake Bay Foundation, gave bay scientists and advocates a chance to observe Isabel's damage first-hand.

Most agreed Isabel had not delivered an ecological disaster on the level of Hurricane Agnes, which flooded the bay with soil and freshwater in June 1972 and reduced bay grasses by 67 percent.

Yet some experts said the hurricane's real toll will not be known until early next summer when bay grasses start to grow and oysters spawn.

Along the shore, grassy slopes were shorn into muddy cliffs 6 feet behind the original shoreline.
"This shoreline erosion is incredible," he said.

Isabel's eye struck to the west of the bay, flooding the estuary with 213 billion gallons of water and thrusting the brunt of the storm against the bay's western shore.

Nutrient and soil runoff into the bay was estimated to be four times greater than normal during the storm, according to the U.S. Geological Survey. But the amount would have been greater had
Isabel brought heavy rains north where the Susquehanna River provides the bay with about half its fresh water.

Near Whitehall Creek, Tiffany Granberg, a field educator for the Chesapeake Bay Foundation, lowered a metal contraption called a 'bottom grab' from the boat into the water. The device descended, re-emerged and spit out a lump of mud.

"This is the stuff that covers over the grass beds, covers over the oysters," Granberg said.

"It's just like taking a big piece of black plastic and putting it over your garden," said Richie Gaines, president of the Chesapeake Guides Association.

Richard Batiuk of the U.S. Environmental Protection Agency grabbed a hunk of the muck and swirled it in a tank of clear bay water to illustrate how the bay became cloudy.

Yet Batiuk said the biggest immediate threat to the Chesapeake's habitat is sewage brought into the bay from floodwater that washed overloaded sewage treatment plants.

Maryland's Department of the Environment closed shellfish fishing on Monday due to the threat of fecal coliform bacteria being absorbed by oysters and clams.

Richard McIntire, a spokesman for the department, said in a telephone conversation that the presence of these bacteria could delay this year's Oct. 1 oyster harvest by as much as a week.

Yet not every scientist on the boat was downbeat about Isabel's wrath.

"We're in good shape, because this is a fall storm," said Robert Wood, a scientist from the National Oceanic and Atmospheric Administration. He said Agnes was more destructive because it hit in early summer when many bay species flourish.

"I saw what I'd hoped to see," Wood said. "Things don't look that different, except on the shoreline."