(Editor's note: This is the last in a series of stories by New Era Correspondent Wendy S. Caldwell. She recently completed a co-op in applied anthropology at Millersville University aimed at understanding sustainable agriculture in Lancaster County.

Lancaster County has long been designated as having the number-one non-irrigated farmland in the U.S.

It also has a reputation for depositing the most nutrient pollution into the Chesapeake Bay.

Nutrients such as phosphorus and nitrogen are essential to the growth of submerged aquatic vegetation in the bay. However, too many nutrients lead to a choking overgrowth of phytoplankton, which depletes oxygen. Without oxygen, aquatic life, including Maryland's celebrated crab and oyster population, dies off.

Harry Campbell, a scientist with the Pennsylvania office of the Chesapeake Bay Foundation, said if the nutrient pollution is occurring in the bay, it's happening upstream as well.

"Think of the bay as a mirror to what is happening in Lancaster County," Campbell said. "Two hundred miles of county streams are in just as bad shape. Aquatic life either has to move to another stream, or it is asphyxiated and dies off."

Agriculture is the number-one cause of impairment of the Chesapeake Bay, according to Campbell. However, scientists with organizations such as the Chesapeake Bay Foundation and the Environmental Protection Agency's Chesapeake Bay Program emphasize that agriculture is not the only pollutant.

"Lancaster County is a significant source of bay degradation because it is at the intersection of a significant amount of urban sprawl and agriculture," Campbell explained.

The Chesapeake Watershed extends north from the bay through the middle part of Pennsylvania and into the southern portion of upstate New York.

Lancaster County farmers, according to Campbell, are doing their part to begin easing the deposit of animal waste directly into the streams that lead directly to the Chesapeake Bay.

"Farmers need money to put in stream buffers like streambank fencing, but they can't always pass along that cost to the consumer," Campbell said, adding that using trees to create forested buffers is most cost-effective for the farmers.

In July, Gov. Ed Rendell signed into law the Resource Enhancement and Protection Act (REAP). The measure provides tax credits for farmers and businesses who implement farm-conservation practices that reduce nutrient pollution.

Across the Commonwealth, 14 watershed associations are hoping to lessen Pennsylvania's reputation as one of the major contributors of nitrate-from-manure runoff into the Chesapeake Bay. The largest of those groups is the Octoraro Watershed Association, based in Chester County.

"We work within a 200-square-mile area covering Lancaster and Chester Counties in Pennsylvania and Cecil County, Maryland," Watershed manager Pat Fasano said. "Seventy-four percent of that land is agriculture, and nearly all of the farmers we help are Amish."

Fasano said he has relied on one-on-one visits with nearly 250 Amish farmers to discuss methods to reduce nitrate runoff into the streams that cut through farmland.

"I rely on an Amish liaison, Henry Beiler, to take me around to Amish farms," Fasano said, adding that the Amish will only meet with him if they feel their farming livelihood is threatened. "Their culture demands that I take time to explain what improvements they can make."

Convincing one farmer at a time will be worth it in the long run, he said.

"This is sustainability at the grassroots level," Fasano said. "And once the Amish see actual improvements on their farms, they will talk to each other and the idea will continue to spread."

The Chesapeake Bay Foundation, which set a deadline of 2010 to clean up the bay before the potential enactment of EPA regulations, emphasizes that farmers are stewards of the land, and therefore, are committed to soil sustainability.

"A well-managed farm is actually much healthier than your average subdivision of homes," Campbell said. "Farms can revert back to their natural states. When's the last time you saw a housing development turned back into farmland?"