How dry we are
The continuing drought in much of the U.S. has raised real concerns about long term fresh water supplies. 2012 was one of our country’s driest years since official records began in 1880. Barges are now scraping bottoms on a shrinking Mississippi River. And we continue to drain Midwest aquifers, like the huge Ogallala, to satisfy demand for more corn and soybeans, as a hundred million cars and trucks roll up to the dinner table for their diet of corn ethanol and bio diesel. In irrigation states like Kansas and Nebraska, a U of MN study under Professor Sangwon Suh reported that 500 gallons of water are needed to grow and process the corn to make one gallon of ethanol.
The 100th meridian of longitude comes down from the north to bisect the Dakotas, Nebraska, Kansas, Oklahoma, and Texas. To the east of the 100th is wet America with its variety of crops and generally adequate rainfall. To the west, except for a wet area in the Pacific Northwest, is dry America of wheat, cattle ranches, and irrigation. The primary water storage for dry America is in the snow packs of its mountain ranges, which feed the rivers during dry seasons. The west’s major river is the Colorado. It brings life to hundreds of cities, 21 million people, and two million acres of farmland in seven states. The Colorado’s dams and diversions were planned when the river’s annual flow was more than 16 million acre feet (MAF). In the drier 21st Century, the flow is now averaging 14-15 MAF. The river’s two major reservoirs, Lake Powell and Lake Mead, are in slow decline, and are currently about half full.
Many climate scientists believe that one of the major effects of global warming will be more drought in parts of dry America, placing the future of cities like Phoenix, Las Vegas, and Los Angeles in jeopardy. Las Vegas water comes from two giant straws placed in Hoover Dam’s Lake Mead. But as Dr. James Powell of USC put it in his recent study of the Colorado, “We can save either Lake Powell or Lake Mead, but not both.”
The thirsty cities of the west are starting to look at the Columbia River, the Great Lakes, and the Mississippi for water. An enduring Minnesota nightmare is the vision of a great pipeline from Lake Superior. Like a giant flexible straw, it snakes its way west to irrigate parched Arizona golf courses, California’s Imperial Valley, and Los Angeles swimming pools. Although the pipeline is not practical, the bad dream persists, concluding with Lake Superior becoming a giant replica of the empty mine pits on the Iron Range. Soaring demand for nonferrous metals will likely revive sulfide mining on the Iron Range, with its potential risk to water supplies.
Minnesota once had large forests of virgin white pine and huge deposits of rich iron ore. Deep layers of our glacial soil were nourished by the waters of our lakes, streams, and aquifers. Now those forests are clear cut, and most of the iron ore is gone, leaving behind those empty pits. As the new year dawns, let’s protect our remaining soils and water supplies.
Relatively stable amounts of fresh water are renewed from the oceans by nature’s giant distillery. But demand accelerates as the world’s numbers and aspirations increase. Conservation and measures like ending subsidized cheap water for low-value crops in arid regions would help to sustain water supplies for future generations.
All over the Earth, our drawing-down of nature’s resources continues. Petroleum based fertilizers and pesticides from industrial farming wash into rivers, causing the growth of dead zones in deltas and the sea. We once fished with lines and nets that muscles could manage. Now, big trawlers with powerful diesel engines trail miles of nets, threatening entire species.
The vengeance for these acts of desecration will not be sudden, as in the great flood of biblical history. Instead, the rivers will gradually silt up the dams, overtop and remove them, and resume their destined routes to the sea. Soils, impoverished and eroded from single-cropping, will no longer nourish our billions. A warming atmosphere, polluted by overuse of carbon fuels, will wreak its own havoc.
The talents in our humanity give us an obligation to the environment first assigned to us when we received dominion over the Earth. There is still time, but not much time, to take seriously the responsibility for the Earth that dominion gives us.
Rolf Westgard recently taught the class “Peak Oil or Peak Water; which will impact us first?” for the University of Minnesota’s Lifelong Learning program.