One of the many arguments made against the Keystone XL pipeline is that said pipeline will be transporting crude oil over the Ogallala Aquifer. In my home region, the humid eastern United States, much of our water comes from surface water - while individual rural homes may have wells, municipal water typically comes out of rivers or reservoirs. In the arid central and western United States, however, groundwater is the primary source of water for human use. Hence the concern over a crude oil pipeline crossing a major groundwater source. Crude oil, as anyone can tell you, is nasty stuff, and is as much as 1% by volume BTEX compounds. BTEX compounds are a family of volatile chemicals with irritant, neurotoxic and carcinogenic properties, and tend to persist in the environment. Much of the opposition to the pipeline has crystallized around potential of crude oil and BTEX leaking from the pipeline and seeping into one of the world’s largest groundwater systems.
So, clearly, we want to keep benzene, toluene, ethylene, xylene and other things ending in “-ene” out of the water supply. But is this the only threat to the Ogallala? Probably not. The aquifer underlies the Great Plains, the so-called breadbasket of the United States. In our industrialized age, intensive agriculture is typically coupled with intensive pesticide application and fertilizer runoff, and the Great Plains are no exception. Like all aquifers, the Ogallala receives some “recharge” water. Precipitation falls on the land, and some of that precipitation works it was down into the groundwater. As the water filters through soil and rock, it tends to pick up dissolved solutes.In the absence of human influence, groundwater may contain elevated levels of calcium, magnesium, iron, salt, chloride, sulfur...even arsenic. Human activities can introduce a range of agricultural contaminants. A recent USGS assessment of the Ogallala Aquifer found elevated concentrations of nitrates, pesticides and arsenic throughout the aquifer. To any Great Plains readers, don’t panic, the concentrations are still well below anything dangerous, but they are still higher than they should be (zero).
All right, so the Ogallala is facing water quality threats. Anything else? Most certainly yes. The Ogallala, like most aquifers, is fossil water. Some new water enters every year, but most of the water present has been in the ground for thousands of years. The water demands of the intensive irrigation that fuels much of our agricultural productivity in the United States are much higher than the recharge rate. Consequently, the aquifer is being drawn down in many areas. The decline in water levels is not uniform throughout the region, but has been enough to provoke concern among local users, and draw attention to the importance of water conservation measures.
The Ogallala isn’t the only strained aquifer out there. Much of the world is dependent on fossil water. Fossil water is in many ways similar to fossil fuels. In much the same way that the discovery of energy-dense fossil fuels freed humans from the constraints of low energy wood burning or early current-turbine power, the discovery of fossil water freed humans from reliance on seasonally unreliable surface water. Again, similar to fossil fuels, the sudden availability of such a large source of a previously difficult to obtain necessity fueled excessive, seemingly wasteful behavior. Take Saudi Arabia. Saudi Arabia is an arid country with the great fortune of being on top of both huge fossil fuel and fossil water resources. In the last several decades, a rising population, a rising standard of living (due largely to the fossil fuels) and such seemingly quixotic national programs as attempting the development of a domestic dairy cow industry have combined to greatly stress the abundant groundwater reserves. Conservation measures are now being implemented, but a good deal of water has already been wasted. Compare this to the popularity of the Hummer, and other vehicles of its ilk.
This isn’t to say that aquifers are all bad. Huge quantities of potable water are still present underground in many regions of the world, and careful use of that water can improve living standards for many who still suffer from drought, parasitic contamination, and the other vagaries of surface water. Just remember, however inexhaustible they may seem, aquifers are vulnerable to human use and misuse. In much the same way that we are slowly learning to live within the limits of fossil fuels, and take advantage of the research permitted by a high level of industrialization to develop alternatives, perhaps we can develop a sustainable groundwater-use strategy out of our current exploitation of the resource.
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