Americans use about 80 billion gallons of ground water daily, mostly for crop irrigation and drinking water supplies. As oil and gas deposits become more difficult to extract, the oil and gas industry is increasingly polluting underground water supplies.
What Is Groundwater?
Ninety-seven percent of the world’s water supply lies in oceans while three percent is fresh. Of the fresh water, about one percent lies under the ground in aquifers, or reservoirs of water in layers of rock below us. In arid areas like the Western US, groundwater is often the only reliable source of water available to people and wildlife.
Groundwater sits in pools underground at depths ranging from just below the surface to many hundreds or thousands of feet down. Some aquifers are replenished in the short term by rainwater soaking into the ground. Other deeper aquifers may be too deep to be replenished and are known as “fossil water.”
Groundwater Pollution
Groundwater has always been vulnerable to pollution from septic systems, underground storage tanks, runoff from streets, and from factory pollution. Today, the oil industry is becoming one of the largest single polluters of groundwater and one of the only sources of industrial pollution at great depths in the earth.
With a large expansion of the oil and gas industry, new sources of deep groundwater pollution are happening because of changing technology and emerging problems recovering oil and natural gas. Easy to recover oil is largely gone from the US and the industry is now focusing on natural gas thousands of feet underground, and on thick, low grade oil deposits called heavy oil.
Fracking Pollutes Groundwater
The natural gas industry seeks ever deeper deposits of natural gas trapped in rock formations. They used a technique called hydraulic fracturing or “fracking” which involves injecting a soup of chemicals under pressure into formations as much as 4000 feet deep. The chemicals and pressure break up rock releasing natural gas which is removed. The chemicals soak into many layers of rock and contaminate aquifers which people may be tapping for farming or drinking or which may feed springs.
The oil industry keeps secret the chemicals it uses for fracking but the Environmental Protection Agency has revealed that some of them are benzene, phenanthrenes, naphthalene, 1-methylnapthalene, 2-methylnapthalene, diesel fuel, fluorenes, aromatics, ethylene glycol and methanol. Some of these chemicals are known carcinogens.
According to the Interstate Oil and Gas Compact Commission, 90% of natural gas wells undergo fracking in the US. The practice has been particularly controversial in New York state where some argue it could contaminate large urban water supplies. The practice is widespread in western states like New Mexico, Colorado, Wyoming, and Montana as well.
Efforts to protect drinking water supplies from hydraulic fracking fluids have been frustrated by oil industry political pressure on the EPA and its researchers during the early 2000s according to the Oil and Gas Accountability Project.
Heavy Oil
A second major source of groundwater pollution from the oil industry comes from heavy oil mining operations in places like Kern County, California. One the largest oil fields in the US is nearing exhaustion in that region with the “light, sweet crude” mostly gone. What’s left if very heavy tar-like oil that is recovered using a great deal of steam injected into wells to liquify the heavy oil and make it viscous enough to pump. This process is called “steam-flooding.”
Not only does steam-flooding use a great deal of water to make steam that could be available to farms, large quantities of “produced water” come out of the wells with the oil. Produced water is groundwater that becomes contaminated with elements like boron, arsenic, chloride, various petrochemicals and radioactive elements. It can kill crops.
With little if any regulation, the oil industry stores produced water in large lagoons which soak into the ground contaminating groundwater. Farmers in California’s Central Valley have found groundwater unusable because of heavy oil operations on nearby lands.
Four barrels of water are required for every one barrel of oil mined by steam-flooding.
Conventional Oil and Gas Operations
The widespread oil and gas pumping operations throughout the US seeking light oil produce wastewater as well. Wells producing oil also produce polluted water which is stored in pits or ponds. Some states have required oil companies to put rubber linings in these ponds to protect groundwater from seepage. In New Mexico the industry is lobbying to have the pit lining requirement rescinded to save money.
The US Geological Survey looked at 2100 private wells in 48 states and found that 20% of them were contaminated with dangerous compounds or microbes. Some of these compounds could be the result of oil and gas operations.
