The Canadian company TransCanada wants to build a 1,702-mile pipeline that will pass through Nebraska's Ogallala aquifer as it transports heavy crude oil from tar sands mines in Alberta, Canada to refineries on the Gulf Coast. Supporters of the Keystone XL pipeline say it will improve U.S. energy security and decrease reliance on Middle Eastern oil. Opponents say that pipelines transporting oil sands crude raise the risk of spills and damage to aquifers and waterways, while extracting and processing the thick oil increase greenhouse gas emissions.
The U.S. Environmental Protection Agency has said that on a "well-to-tank" basis the heavy crude extracted is 82 percent more carbon intensive than conventional oil. That estimate sits in a middle ground between widely varying claims offered by industry and environmentalists.
Since the pipeline will cross an international border, TransCanada must get a presidential permit from the State Department before it can build and operate the line. In July 2010, the EPA gave the State Department's first draft Environmental Impact Statement (EIS) of the project the lowest possible grade of "inadequate," creating an inter-agency tussle that has delayed the permit decision. Although a second draft EIS did better, the EPA said more analysis was still needed to fully evaluate the environmental risks. The State Department's final environmental review of Keystone XL is expected this month.
The Ogallala aquifer has emerged as an important point in the debate. In June, two scientists from Nebraska called for a special study to determine how an oil spill would affect it, and Republican Sen. Mike Johanns of Nebraska has asked the State Department to consider an alternate, more easterly route that would avoid it. Twenty scientists from top research institutions recently signed a letter urging President Obama not to approve the pipeline because of environmental concerns.
Here's a primer on why people are worried.
Why is the Ogallala Aquifer So Important?
Because it's the most heavily used aquifer in the United States and supplies about 30 percent of the groundwater pumped for irrigation nationwide. The Ogallala aquifer (also known as the High Plains aquifer) covers 175,000 square miles, an area larger than the state of California, and spans eight states — Nebraska, South Dakota, Wyoming, Colorado, Kansas, Oklahoma, Texas and New Mexico.
Most of the residents in this region depend on the aquifer for their drinking water, and the farmers there produce about a fifth of America's agricultural output, worth at least $20 billion a year.
The Ogallala is particularly important to Nebraskans. It provides 78 percent of the water used by residents and industry and 83 percent of the state's irrigation water. Nebraska's farming industry contributed $15 billion to the state economy in 2009, worth 18 percent of Nebraska's gross domestic product for that year.
What Would Happen if Oil Leaked Into the Aquifer?
The extent of the damage would depend on the size of the spill and location of the leak. The aquifer is so big that a single spill would contaminate only part of the aquifer, said John Gates, an assistant professor of earth and atmospheric sciences at the University of Nebraska and one of the scientists who has called for more research. Because so little is known about how oil would move through the sandhills, it's impossible to say for sure what the impacts would be.
Even a fairly localized spill could cause serious problems. The Ogallala is already under threat from over-depletion, because people are pumping out groundwater faster than it can be replenished by rain and snow. The strain is apparent in northern Texas, where some fear another Dust Bowl as the water table continues to drop.