At 4:45 a.m., the lights flicker on in the farmhouse bedrooms.

One by one, the Potts family files downstairs--Eddie, Marty, Jessica, Justin and Lindsay--past the TV set in the large open family room, through the kitchen and out the creaky screen door to the fields and barns on their 267-acre farm outside Hillsboro.

Each has a task. Justin, 19, leads 80 of their 200 head of cattle from the south fields to the milking parlor on the hill behind the house. His father, Eddie, turns on the milking machines and inspects each nozzle. Jessica, 21, shovels manure from the parlor's floor--Eddie is a stickler for cleanliness. Lindsay, 17, helps her mom, Marty, feed about a dozen calves.

"Everybody works here," said Marty, 46. "This is a full-fledged family operation."

There are no such things as weekends or holidays. The cows are milked every 12 hours, 365 days a year--as it has been since the Potts homestead was established in 1747, as they hope it will be for years to come.

Its future lies with the family's ninth generation--Jessica, Justin and Lindsay. Since the three children were knee-high, they've tagged along behind their parents and grandparents, who now live in a rambler near the farmhouse. Unlike many of their peers, who have lost interest in agriculture amid Loudoun County's fast-growing development, each is committed to the farm.

But they are a rare breed. As Marty made lunch one day, she ticked off the names of farmers who have sold their land because the next generation doesn't want it or can't afford to keep it going. The Potts's place was one of 300 dairy farms in the county in the 1950s. Now it is one of three.

"They just got tired or decided they'd rather cash in and retire to Florida," Marty said. "A lot of people didn't have a younger generation like us. Justin, Lindsay and Jessica are it for Loudoun County in dairy farming."

Jessica, a senior at Virginia Tech, and Justin, a sophomore, are studying dairy science. Lindsay, who will be a senior at Loudoun Valley High School this year, plans to follow them.

Most summer days, Eddie lets Justin take the lead in telling the others what to do so he can help a neighbor dig a ditch or spend a day at a farm show eyeing new equipment.

The final weeks of August call for all hands. It is "crunch time," as Marty calls it. The drought is forcing them to harvest 160 acres of corn a month earlier than usual. They've already cut into the 225 tons of silage meant to feed the cattle come winter. Marty described the half-developed ears of feed corn as "Milky Way candy bars without the gooey filling on the inside."

That could mean money lost because it will take more to fatten the cows and unusually bad winter weather might mean buying feed elsewhere or thinning the herd. That delicate balance is the family's constant reality.

"There's always the possibility that it won't be profitable or it won't be worth the time and effort to do this anymore," Justin said.

But he and his two sisters said they have been inspired by their parents' dedication to the farm, which was an apple orchard before it became a dairy operation. They understand the importance of caring for a calf from birth until it is producing eight to 14 gallons of milk a day. They know that a bottle of medicine for an ailing cow can cost as much as $300, that losing the cow to disease can mean a loss of $750 to $7,000.

They laugh at the countless times they've explained their responsibilities to their friends, who ask: Why can't you stay out late? Why don't you just have somebody else do it?

"It's our lives," Lindsay said. "There's nobody else to do it."

Getting up to help milk and feed before school and coming right home after the last bell has always been their first priority--but not their only one. Jessica and Lindsay joined Girl Scouts in grade school and traveling 4-H dairy judging teams. Justin played basketball at Loudoun Valley, although he once missed preseason practices for a national 4-H convention.

Justin and Jessica joke that compared with farm work, college is luxurious. They get to sleep in until 7 a.m. during the week and 11 a.m. on weekends.

"Dad always tells us you can't get anything done if you sleep in," Lindsay said. "He wants to make sure everything gets done and it gets done right. Quality, that's what he wants."

Over lunch at the dining room table, Justin and Lindsay discussed what it will take to keep the place running. Another dry year like this one will be trouble, Justin said.

Lindsay chided him for sounding like their grandfather, Edwin, who often recites the perils of farming in general and growth in particular. "Ever since they put in that Dulles airport," Edwin will say, "they've got every kind of people living out here."

Edwin, 74, calls himself the "gopher" on the farm and rides between barns and fields carrying tools on a four-wheeler after having a knee replacement two months ago. He shakes his head about neighbors who live in half-million-dollar homes on five or 10 acres and tell him how much they love the view. But "you can't eat a view," Marty said.

"That's right!" Edwin exclaimed. "There's only about 2 to 3 percent of the people raising food for the rest of the world. Somebody's got to feed all these folks."

And he tipped his hat to his grandchildren, who were outside baling hay.

After college, Justin plans to come home.

"I don't know how long we'll be able to keep going," he said. "You've got to love what you're doing. And having all this responsibility. . . . There's days where I love it. I love being outside and working. I think this place is beautiful.

"Then there are times where I ask, 'You really want to do this?' " he said.

Lindsay giggled. She still has a year of high school, and beyond that her future is a huge question mark.

"I want to do more than stay home on the farm," she said.

She wants to educate people about farming, especially young students who sometimes come to the farm for tours in search of the cow that produces chocolate milk.

For Jessica, the future will be here next spring, and she is a little ambivalent. She spent the summer at an internship with a Richmond estate appraisal company and a few weekends helping at the farm.

"I can see myself contributing" to the farm, she said. "Yes, I want to see how I can add to it."

Her mother has cautioned them about coming back too soon, taking the reins too early. For her, the daughter of an Air Force colonel, and, Eddie, 49, it was an obvious place to raise a close-knit family after he served his Army stint as a milk inspector.

For Justin, there is pride in knowing he can take the reins.

"Our family has stayed with it for so long," he said. "To think we can still operate in what Loudoun County has become is something special."