ON THE POCOMOKE RIVER -- Joseph Fehrer Jr. paddled through dirt-black water and past islands of gnarled roots to an ancient cypress tree.
On one side of the colossus stretched 1,000 acres of farmland where a developer plans to build 2,170 homes, a grocery store, a movie theater and shops that would triple the population of Snow Hill.
On the other side of the tree, across the Pocomoke River, sits a 9,300-acre nature preserve that Fehrer's father helped create to protect this rare and vanishing cypress swamp.
The developer - like other builders on the booming Eastern Shore - argues that his project will improve the river's water quality because it will replace farmland, whose fertilizer pollutes nearby streams.
But Fehrer worries about the threat of bulldozers to an ecosystem that offers a spectacular glimpse of primitive America. He and other conservationists said they would prefer chicken manure to subdivisions, with their traffic and acres of blacktop. "Personally, I'd much rather see a farm grow corn than houses," Fehrer, land manager of the Nature Conservancy's adjacent Nassawango Creek Preserve, said as he watched an osprey take off from the cypress tree.
That environmentalists are suggesting that farms are good for rivers is a change. Farm fertilizer has been considered a major source of pollution to the Chesapeake Bay and, here along the Pocomoke, was blamed for an outbreak of toxic algae that caused a public health emergency in 1997.
Recently, the Chesapeake Bay Foundation has urged a "save the farm, save the bay" approach, arguing that sprawl poses a far more dire threat than farm pollution. But fertilizer runoff remains a problem here, state water quality data suggest.
Nine years ago, the state shut down a seven-mile segment of the Pocomoke downstream from Snow Hill when an explosion of Pfiesteria algae was blamed in part on chicken manure fertilizer. The bloom was linked to fish kills, illness and memory loss among watermen.
The crisis attracted national media attention and inspired Maryland's landmark 1998 Water Quality Improvement Act. The state law required farmers to submit nutrient management plans designed to minimize their use of fertilizer.
Since then, 260 of the 261 farmers in surrounding Worcester County have started self-monitoring and report their fertilizer use, according to the state Department of Agriculture.
Despite the law, nutrient pollution levels in the Pocomoke have not improved since 1998, according to data from a state water monitoring station. Also, the river's water quality, as measured by oxygen levels, has worsened, the state data suggest.
"The law didn't do anything," said Virgil Shockley, a chicken farmer and Worcester County Commissioner. "It was picking on the wrong people. You've got these new housing developments with the big new green lawns, and I'll bet you anything they put more fertilizer into the Pocomoke River than any farmers growing corn or soybeans."
Patricia M. Glibert, a professor at the University of Maryland Center for Environmental Science, said farm pollution in the Pocomoke River remains significant but would likely be worse without the fertilizer management required by the 1998 law.
The developer of the Snow Hill project, called Summerfield, claims his subdivision will be better for the river's health than the farmland it will replace.
"There is no question that there will be a net benefit to the river," developer Mark Odachowski said of his construction. "There will be less runoff of nitrogen, because the nitrogen that was put on this farmland was among the highest in the state."
He said his project will include a $12 million sewage treatment plant, a storm water containment lake, and a 166-acre zone of preserved trees along the Pocomoke River. In March, voters approved an annexation that allows the project to proceed.
Similar assertions of environmental improvement are being made by the developers of a $1 billion proposal to build about 2,700 homes and a golf resort on farmland near the Blackwater National Wildlife Refuge in Dorchester County.
Beth McGee, senior scientist at the Chesapeake Bay Foundation, said it's probably true that poorly managed farms create more polluted runoff than some housing.
But she said farms are generally healthier than subdivisions when they minimize fertilizer use and plant buffer strips of trees and grass along streams. A runoff comparison, she said, doesn't take into account increased traffic and air pollution and the sprawl that radiates from new subdivisions.
The Pocomoke River meanders for 73 miles from Delaware to the Chesapeake Bay through both kinds of threats, the old farms and the new development sites.
On a recent morning, Fehrer provided a tour of a section of the river south of Snow Hill.