If oil were to reach groundwater, movement of oil and any resulting contaminants that enter groundwater would be slow and limited in scope, likely to hundreds of feet at most, even in sandy soils and even in the vast Ogallala and High Plains aquifers.
Throughout North America, communities and individuals rely on clean groundwater for drinking. In Nebraska, the Ogallala and High Plains aquifers are special, containing high-quality water resources that help Nebraska to be a leader in food production for the country and the world as well as contributing to the quality of life for residents who rely on the water for drinking. While Keystone XL incorporates unprecedented safety measures to reduce the risk of a release, the viability of these critical resources is safe even if there were a release that reached groundwater.
Hydrocarbons, including the crude oils that will be transported in Keystone XL as well as refined petroleum products (such as diesel fuel, gasoline, etc.), behave very differently in groundwater than other common contaminants, such as nitrates. In groundwater, hydrocarbons are consumed by naturally occurring microbes, which limits their spread. Movement of dissolved hydrocarbon constituents typically is limited to less than 300 feet from the source. Movement is only in the direction of the flow of water through the ground. The rate of movement before equilibrium is established is slower than the movement of the groundwater.
The inherent limitations on the impacts of an oil spill in groundwater is one of the reasons why the integrity of Nebraska’s aquifers has been safe despite oil wells in western Nebraska that have been pulling oil up through the aquifer from reserves below since the 1940s and despite pipelines moving vast quantities of petroleum across the aquifer in Nebraska since the 1950s.
For more information: See “Pipeline Safety and the Ogallala Aquifer” fact sheet. Additional information is also available in the Keystone XL Final EIS, Section 3.13. See the U.S. Department of State New Keystone XL Pipeline Application.