US: Drier still
A little over two years ago we discussed the increasingly perilous state of the Ogallala aquifer. In particular we looked at the nature of the aquifer, the diminishing quantity of water available, and some of the likely consequences of continuing to over-stress this resource. Now, there are more data available to suggest that it is not just the areas reliant specifically on the Ogallala that are under threat, but the rest of the US as well.
America’s breadbasket
The current state of the Ogallala is a good place to start. It sounds like a terrifying state of affairs itself, but even more so when looked at in the context of the rest of the US’s water situation. The Ogallala Aquifer, also known as the High Plains Aquifer, is a wide but shallow body of water sitting under the Great Plains in the United States. It is one of the largest aquifers in the world, with an area of approximately 174,000 mi² (450,000 km²), and is believed to be the largest body of fresh water in the world. It sits beneath parts of the states of Colorado, Kansas, Oklahoma, Nebraska, New Mexico, South Dakota, Texas and Wyoming.
About 27% of the irrigated land in the United States lies atop the Ogallala, which yields about 30% of the nation’s groundwater used for irrigation. The irrigation from the aquifer has allowed the region to become known as ‘America’s breadbasket’, producing 20% of the US’s grain and maize.
But that moniker is now under threat. Indeed it seems likely to lose it, and in the relatively near, rather than the distant, future.
Data presented in 2010 by Dr. Kevin Mulligan, a professor of Economics and Geography at Texas Tech, show that the Ogallala Aquifer is being drained at a rate of approximately 800 gallons per minute.
Since the High Plains Aquifer began to be tapped on a large scale in the early 20th century, a vast amount of water has been drained from it. In 1940 the average depth of the aquifer was approximately 240 feet, but today the average depth is just 80 feet. In some areas of Texas the water is gone completely. According to the US Geological Survey (USGS), in a report last updated in 2012 entitled Selected Approaches to Estimate Water-Budget Components of the High Plains, 1940 through 1949 and 2000 through 2009, a volume equivalent to two-thirds of the water in Lake Erie has been permanently drained from the Ogallala Aquifer since 1940.
The depth of the water in the Ogallala ranges from almost 400 feet (122m) under parts of the northern plains to between 100 and 200 feet (30 to 61m) throughout much of the south. Present-day recharge of the aquifer with fresh water occurs at an exceedingly slow rate suggesting that much of the water is ancient, dating back at least to the last ice-age. Draining water from the Ogallala is, for all practical purposes, mining a non-renewable resource.
While groundwater is usually considered a renewable resource, especially when carefully managed, reserves in the Ogallala replenish particularly slowly. The USGS has performed several studies of the Ogallala to determine how much water is entering the aquifer in the form of groundwater recharge from the surface, what is being removed from the aquifer in the form of pumping and natural loss to streams, and what the net change in storage is.
A significant problem with the Ogallala, and one that it is unlikely we can ever solve, is that although it is an unconfined aquifer (so should be able to receive recharge) much of the aquifer is topped with a layer of caliche that is to all intents and purposes non-permeable. As a result almost no water ever makes it back into the aquifer.
In a 2012 interview with National Geographic USGS director Marcia McNutt said “[I]n less than 100 years we are seriously depleting what took Nature more than 10,000 years to fill.”
David Brauer of the US Agriculture Department’s Ogallala Research Service, has warned that the fact of the Ogallala drying up is something that can be postponed though good practice, but not avoided. In an interview with the UK’s The Telegraph he said “The Ogallala supply is going to run out and the Plains will become uneconomical to farm. That is beyond reasonable argument.” He added, “Our goal now is to engineer a soft landing. That’s all we can do.”
The USGS report points out that the rate of depletion of the Ogallala is increasing. The researchers used a range of different models to account for the various credits and debits to the aquifer. According to their data the average annual depletion rate between 2000 and 2009 was more than twice that during the previous fifty years. The depletion is most severe in the southern portion of the aquifer, especially in Texas, where the water table beneath sizeable areas has dropped 100-150 feet; in some areas it has dropped more than 150 feet.
In context
When, not if, the Ogallala is no longer useful as a source of water the effects of its running dry will be felt further afield than just in the areas that are directly reliant on the aquifer. The US is drying out elsewhere as well. According to the US National Academy of Sciences, the US interior west is now the driest that it has been in 500 years.
In recent years central parts of the US have experienced wildfires that have burnt millions of acres of vegetation. In 2011 in Texas, for example, wildfires burnt 3.6 million acres.
In the 1930s and ‘40s the conditions were ripe for the wind to pick up huge clouds of dust, forming dust storms, which eventually blew out into the Atlantic. This is happening again – the press is full of reports of dust storms of the sort that have not been seen in the US for more than seventy years.
The burnt areas left by the recent wildfires are helping to bring about these conditions again, and they are not the only contributing factor.
It appears that extremely dry conditions are likely to continue and worsen in parts of western North America for decades to come. In an interview with the Vancouver Sun Jeannine-Marie St. Jacques, a paleoclimatologist at the University of Regina, said that a decade-long drought could be just the beginning, and that history tells us that longer periods of drought are a common and natural phenomenon for that part of world.
At the American Association for the Advancement of Science conference in Vancouver in 2012 St. Jacques et al. presented their research, wherein they studied tree ring data to discover historical climate patterns for North America. In the Vancouver Sun St. Jacques said “What we’re seeing in the climate records is these megadroughts, and they don’t last a decade — they last 20 years, 30 years, maybe 60 years, and they’ll be semi-continental in expanse. So it’s like what we saw in the Dirty Thirties, but imagine the Dirty Thirties going on for 30 years. That’s what scares those of us who are in the community studying this data pool.”
- Some US water facts
Scarcity
18 States are currently facing droughts, according to the US Drought Monitor
40% of all US water withdrawals are for export
Unless measures are taken, California will demand three times more groundwater than can be supplied over the next 100 years
Florida‚ rapid use of groundwater has created thousands of sinkholes that devour anything, houses, cars and shopping malls, unfortunate enough to be built on top of them
The Western US is facing its warmest decades in over 500 years
In 2007, Lake Superior, the world’s largest freshwater lake, dropped to its lowest levels in 80 years and the water has receded more than 15 meters from the shoreline
Lake Mead, the vast reservoir of the Colorado River, has a 50% chance of running dry by 2021
Quality
35% of US rivers and streams are too dangerous for fishing, or drinking
60% of US lakes are too dangerous for swimming or drinking because of massive toxic runoff from industrial farms, intensive livestock operations and the more than 1 billion pounds of industrial weed killer used through the country each year
Two-thirds of US estuaries and bays are moderately or severely degraded
4.5% of beaches are closed or under advisory at a given time
1.5 million metric tons of nitrogen and phosphorus pollution are carried by the Mississippi River into the Gulf of Mexico every year
Source: food&waterwatch
Unsustainable
It is projected that repairing and expanding the US’s decaying drinking water infrastructure will cost more than one trillion dollars over the next 25 years, and as a result water bills will likely approximately triple over that time period. This makes the amount of water being used by US citizens unsustainable in terms of their own pockets as well as the amount remaining in water sources.
The US currently uses approximately 148 trillion gallons of fresh water a year. A huge amount of this is consumed in parts of the US that are naturally arid, where in nature water usage would be very low. So other water sources, not just the Ogallala are under stress. For example, Lake Mead supplies about 85% of the water consumed by Las Vegas, and since 1998 the level of water in Lake Mead has dropped by about 5.6 trillion gallons.
Elsewhere, it has been estimated that the state of California only has a 20 year supply of fresh water left, and that the state of New Mexico only has a 10 year supply of fresh water left.
And it is not just a question of water levels dropping in the various sources. Pollution from cities and industrial centres is exacting a heavy toll. Approximately 40% of all rivers and 46% of all lakes in the US have now become so polluted that they are no longer fit for human use.
There is no quick fix for the problems outlined above. Indeed, some of these problems cannot be solved – the depletion of the Ogallala cannot be reversed and there is no alternative water source available that can replace it. The pollution problems can be solved, but not overnight.
The most frightening aspect of the increasing water scarcity in the US is that it is not a problem in the future that can be planned around, but one that is already starting to bite.