ON THE SEVERN RIVER -- The redhead grass grows thick, wavy and long as a mermaid's hair. A sunfish slips between the strands, its bright orange belly plainly visible through three feet of clear water.
The pollen released by the grasses' blooms casts a pale gold mist across the river's surface. It lies in long, wide ribbons along the shore and across the flats.
"This is a gift," said John Page Williams, senior naturalist at the Chesapeake Bay Foundation, poling a skiff across the underwater meadow. "It's showing us what we could have if we really restore this bay."
The drought that is parching farm fields and drying up wells on shore has produced a boon for the bay, experts say. Underwater grasses, hard hit by decades of pollution, are rebounding.
And wherever new growth appears, fish, crabs, and birds follow "immediately," said marine scientist Bob Orth, an expert on the underwater plants.
"It's like they're holding up signs, `grass here,'" said Orth, a researcher at the Virginia Institute of Marine Science.
Experts say the shortage of rainfall means that less sediment and pollution are being washed into the bay's tributaries. With less nutrients to fuel algae blooms that cloud the water, the grasses are getting more sunlight and responding with vigorous growth.
Not all the drought's effects are good for the bay. Higher than usual salinity levels are forcing some bay creatures out of areas they normally would use and may encourage the spread of oyster diseases, which have ravaged the bay's shellfish industry, Williams said.
Anne Arundel County conservationist John Flood said he has seen trees dying along the banks of the South River; he blames exposure to too much salt. And Orth said some varieties of underwater grasses can't tolerate high salinity and may die because of it.
For now, the reports coming in from scientists, watermen and boaters are upbeat, although it will be months before researchers can document the underwater meadows' spread.
Orth has flown over the lower third of the bay as part of his annual aerial survey of bay grasses. He is finding dense grass beds, and several new ones from the Potomac River and Tangier Sound south to the bay's mouth.
Williams and other conservationists are surveying the Magothy, South and Severn rivers by boat, and finding new grass beds there too.
"The whole upper Western Shore is looking really good," said Michael D. Naylor, a biologist with the Maryland Department of Natural Resources.
It's a trend that began in the late 1990s with below average rainfall, Naylor said.
"Low rainfall has translated to low runoff, and the water is very clear," Naylor said. "When you get enough plants in one area, the plants slow down the water movement and make the water even more clear.
"When the beds get big enough, once you get on top of them the water is gin-clear and it's spectacular -- just teeming with life," Naylor said. "Anyone who gets into a grass bed like that will never again question why grass beds are important to the bay."
Abundant underwater grasses clarify and aerate the water, protect the shore from erosion, and provide food or shelter for virtually every creature that lives in the water or near it.
Unlike the forests that cloaked the land when Europeans settled here, these underwater forests went unmapped until modern times. No one knows how great their expanse was.
Experts think about 600,000 acres of bay bottom were once covered with grasses that grew wherever the bottom was soft enough to hold a seed and the water was shallow enough for light to reach it.
In these aquatic havens young fish, crabs and clams hid from hungry predators. Vast flocks of water birds nibbled on blades, roots and seeds. Ospreys, eagles and herons hunted fish in the shallows. So did otters, raccoons and people.
But the grasses waned as polluted runoff from land fueled thick algae blooms that turned bay waters murky and blocked the plants' sunlight.
From the 1950s to the 1990s, the declines were extreme. The growth surrounding one small island in Tangier Sound fell from 6,000 acres in 1952 to 83 acres in 1997, Naylor said.
Orth found about 69,000 acres baywide last year.
The totals remain far short of official bay restoration goals -- endorsed by the bay states and the federal government -- that call for 114,000 acres as a preliminary target with more to come.
Even with this year's increases, the experts expect the bay will be far short of that interim goal. To reach it would require sharp reductions in the flow of algae-feeding nutrients into the bay.
Sewage treatment plants would have to remove more nutrients from wastewater, experts said, and homeowners would have to upgrade septic tanks that are unseen pollution seeps.
Farmers and suburbanites would have to reduce fertilizer use, and everyone would have to help reduce nitrogen emissions from auto tailpipes by driving less or driving more fuel-efficient cars.