While there is growing awareness of the depletion of fossil fuels, there is less attention paid to the depletion of fossil water. Underground aquifers are essentially fossil water. They can be tapped to make places habitable that would otherwise not be, and to make agriculture possible in places where it would not be. But if the water runs out, those areas would become barren and uninhabitable, essentially ghost towns. There are many examples in history of regions that have become unlivable when the water dried up. If the water in an underground aquifer is used faster than it can recharge, it is a non-renewable resource. This is even more of a concern because water is necessary to grow food and there are no substitutes for water (sorry economists). Of equal concern is pollution of this essential water supply.
It seems we're well on our way to repeating the mistakes of classical civilization:
IMAGINE you are a farmer in the center of the country, where it seldom rains enough. Now imagine that a well driller came to your farm and told you that he could bore a hole deep into the ground, and that forever after you could pump out as much water as you needed to grow your crops. That is exactly what happened on the Great Plains in the mid-20th century. The wondrous resource containing all that water was the Ogallala Aquifer.Running Dry on the Great Plains (The New York Times)
The Ogallala underlies portions of eight large states — 174,000 square miles of crop and range land all the way from South Dakota to Texas. Over the last several months, it became about as famous as a geologic formation can get. With the nation’s environmentalists at their side, Nebraska landowners battled ferociously against the Keystone XL pipeline, which would have carried oil extracted from Canadian tar sands through the environmentally sensitive Nebraska Sand Hills. If the pipeline leaked, they argued, chemicals and oil would seep down into the aquifer, contaminating a precious resource responsible for 27 percent of the nation’s irrigated agriculture.
They won — for now. President Obama agreed last month to reconsider the pipeline’s route. So is the Ogallala now safe? Not quite. Regardless of whether the pipeline was a good or bad idea, it was never the real danger. The true threat is posed by agriculture as it’s currently practiced on the Great Plains by the farmers themselves, many of whom opposed the pipeline vehemently. The aquifer is being wasted and polluted. Wasted, that is, on corn, a thirsty crop that requires over 20 inches of irrigation water in parts of the Plains. And polluted with pesticides and nitrogen fertilizers.
It’s not that I don’t empathize with the Nebraska farmers. I grew up on a Kansas farm. Like them, we called our Ogallala water “precious” and bragged that it was the best in the world. But the aquifer’s only natural recharge comes from rain and snow. In our Kansas district, less than half an inch of that reached the aquifer in a given year. We were allowed to pump out over 30 times that amount.
When I expressed concern, my father assured me that the government would step in to stop us someday. Until then, he liked to tease, “I got mine!” But the government has not stepped in. Controls imposed by local water districts — run by irrigators themselves — and by state legislators dependent on the farm vote have been minimal at best.
As a result, in some areas of Kansas and Texas, farmers can no longer pump enough to water their crops. If current withdrawal rates continue, usable water in most areas will be gone by the end of this century.
The Ogallala is a geologic formation, not an underground lake that can be widely contaminated by a localized spill. Water fills the spaces between sandstone, gravel, clay and other sediments, which slow the water’s lateral travel. A pipeline leak would have been minor compared to the damage that chemically dependent agriculture causes.
Chemicals trickle inexorably downward with each rainfall or application of irrigation water, creating a situation that the Geological Survey has referred to as “creeping normalcy.” Over the coming decades, it warned, contaminants will continue to creep down into the aquifer, and more wells will exceed federal safety levels.
Already, 14 percent of all Ogallala irrigation wells tested contained one pesticide or more. Most common was Atrazine. This herbicide, used ubiquitously in cornfields, is a known hormone disruptor and is suspected of, among other things, retarding fetal development. Five percent of the irrigation wells contained nitrate levels equal to or in excess of safety standards set by the Environmental Protection Agency. Excess nitrate levels in drinking water can impair the blood’s ability to deliver oxygen in infants, causing “blue baby syndrome.”