The Ogallala Aquifer lies beneath the Great Plains of the U.S. stretching from South Dakota to central Texas. The Ogallala is endangered by declining water levels and pollution from above. This is a serious matter since the aquifer provides irrigation for about one-third of the groundwater irrigation in the U.S. The proposed path of the Keystone XL carries it across land that is particularly permeable to spilled oil.
Physical Characteristics of the Ogallala
The water that fills the Ogallala comes almost entirely from rain and snowmelt. The land and weather above the aquifer is not suitable for rapid and complete recharging — refilling — the Ogallala. Most of the region is semiarid and precipitation is not available in sufficient amounts to replace water removed for use in farming and by homes and cities.
The Ogallala is not a big, empty lake of subterranean water, but a geological region filled with sandstone and other kinds of formations where open spaces are filled with water that can be removed by pumping. Technically, the aquifer starts at the surface or at least where the soil is saturated with water and extends in some places to a depth of about 500 feet, but that depth varies.
The 174,000 square mile area is shrinking as water is being removed faster than it is being replaced.
Recharging the Ogallala occurs primarily by percolation — seepage of water through soil. Therefore, soluble toxic substances on the soil can be dissolved and find their way to the water below. The soil over the Ogallala varies in permeability, and some places allow more water to seep through due to the nature of the soil. Nebraska is the most permeable area over the Ogallala, and water finds it way through the sandy soil with relative ease.
The Ogallala is Already Facing Pollution
As might be expected, an aquifer located beneath expansive farmlands might be threatened by pollution from chemicals used in fertilizers and pesticides. Such is the case with the Ogallala. Fourteen percent of tested wells test positive for Atrazine — a pesticide that can cause birth defects in humans. About five percent of irrigation wells are positive for nitrates which can cause problems in infants.
The Nebraska-Kansas regions have shown contaminants like 2,4-D — a herbicide linked to cancer and other disorders —over 25 years ago. Generally speaking, however, the vast majority of wells meet federal standards for safe drinking water.
The Danger of Pollution from Keystone XL is open to Debate
Although there are numerous websites that warn of looming contamination, hard facts are hard to find about the possibility of future spills. Many environmentalists are concerned that the sponsoring company of the pipeline — TransCanada — has had numerous spills from existing pipelines.
TransCanada confirms leaks and spills but claims that the amounts of the spills were, in the majority of incidents, less than 50 barrels. Activists are most concerned that the pipeline will be underground where a leak might not be found before dangerous contaminants have begun to percolate to the Ogallala.
Crude oil is not one thing, but many different chemical compounds, some of which are toxic in very small amounts. Benzene is found in crude oil and is a known carcinogen.
TransCanada offers assurances that the pipeline will be well-contained in concrete and closely monitored. Leak detection systems are capable of detecting even very small leaks.
Keystone XL Crude is Dirty and Difficult Tar Sands Oil
Tar sands crude is heavy and does not move easily through pipelines like conventional crude. The nature of tar sands increases the likelihood of leakage, so say opponents.
Keystone XL will deliver large perhaps 900,000 barrels of tar sands crude daily to U.S. refineries. Tar sands oils requires enormous quantities of water in the refining process, and that polluted water will become part of the problem — it is held in large manmade tailing ponds. The water therefore becomes a second source of possible groundwater pollution.
The Ogallala Aquifer is such an important source of water that any threat to it should be taken seriously and all practical prevention should be exercised. With the Ogallala already being somewhat polluted and decreasing in volume, extra caution seems justified. Water sources are decreasing in the U.S. as demand increases. Likely, the Keystone will proceed after its route and construction are thoroughly reexamined. In the past three years, oil demand in the U.S. has decreased and that trend diminishes immediate demand for new oil from Canada.
Souces:
"Running Dry on the Great Plains," nytimes.com. (Accessed February 1, 2012)
"Ogallala Aquifer," ogallala.ars.usda.gov. (Accessed January 31, 2012)
Harvey Craft - I am a retired educator with diverse experience. I read anything science, education, and history. I write to share what I learn.
