|At the heart of the controversy is the Ogallala Aquifer, which runs beneath the Sandy Hills area of Nebraska
Nebraska rancher Karl Connells doesn't want a million barrels of crude oil moving across his pasture every day.
On a bright Autumn afternoon recently, he showed me the route that a giant proposed oil pipeline would take across the land his family has owned for over a century.
"There's a plum thicket next to the fence on our property," Connells said, pointing a weathered hand. "It'll be just a little bit to the south of there, and they'll scrape the soil back and have a pile a the topsoil and a pile of the sand they’ve dug out the ground and and then the pipeline goes down southeast."
He's talking about the proposed 2,700km Keystone XL pipeline that would carry oil from the Athabascan Tar Sands of Alberta, Canada, to refineries in Oklahoma and along the Gulf coast of Texas.
Connells, who fears pipeline construction would destroy the fragile, sandy soil of his grazing land, has refused a $15,000 offer from pipeline company TransCanada, to access his property. "I'm the 4th generation here. I'm not gonna just sell out at a whim so they can build their pipeline," he says.
This part of Nebraska is known as the Sand Hills, an area of ancient wind-blown sand dunes covered by a thin layer of grasses.
Early settlers shunned the Hills as unsuitable for farming; later, cattlemen realised the 50,000sq km region was ideal for grazing. Today, the Sand Hills have become the centre of the most vociferous opposition to the pipeline project.
Mostly, it's about water. The Sand Hills sit atop a vast underground body of fresh water called the Ogallala Aquifer. Connells took me to a stock tank on his land. Flipping a switch, he activated a pump, and clear, cool water streamed from a pipe. Connells took a plastic cup, filled it from the pipe, and offered it to me. The water tasted pure and sweet.
"It's the softest, cleanest water you'll find anywhere," the rancher said.
TransCanada's 91cm pipe would run straight through the Sand Hills and the aquifer.
The water here is so close to the surface you can dig down less than a metre and hit groundwater. In the spring, lakes and ponds form in low lying dips and sloughs. In many places the pipeline would be completely submerged in water.
Opponents fear that a pipeline leak would poison this precious resource. And they have good reason to worry - another Transcanada pipeline in operation for only a year has already sprung leaks nine times.
The pipe would carry not only raw tar sands crude full of heavy metals like mercury and arsenic, but chemicals introduced into the thick sludge to make it flow easily through the pipes, such as benzene, a known carcinogen.
Nurse Cindy Myers has been rallying opposition to the pipeline.
"One spill into our aquifer, and it can spread for miles underground," she says.
"If our water is contaminated we have no water for the cattle, we have no water for us to drink. On my property, if my well were contaminated, our property value would be zero. If we don't have water we have nothing."
Myers and other opponents testified against against the pipeline in a series of often-rancorous public meetings in Nebraska towns and cities.
While many of the people who live in the Sand Hills believe the pipeline threatens their environment and their livelihoods, however, others, including businesses, union groups and the oil industry, say it will generate thousands of much needed jobs and decrease US dependence on oil imported from the Middle East.
John Kerekes, a senior official with the American Petroleum institute, the oil industry's lobbying organisation,
says the economic benefit outweighs the possible environmental costs.
"We hope that this $7bn private sector investment is going to create up to 20,000 jobs. Everywhere from the folks actually laying the pipe and welding it to everybody meeting the supply needs, the local hardware store, restaurant, bars and barbershops."
Back on his ranch, Karl Connells says he'll fight to keep TransCanada off his land. He cites approvingly a Wyoming law called the Castle Doctrine that permits property owners to shoot unwanted trespassers. While the law doesn't apply in Nebraska, Connells says all options to protect his land - including the use of force - are on the table.
"Its still my property," the rancher says defiantly. "I pay taxes on it, it's up to me to decide what to do with it. And I'm not gonna let a foreign company come in here and invade on that and destroy my property."
The final say on whether to build the pipeline rests with Barack Obama, the US president. His decision is expected before the end of the year.