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The Ogallala: Preserving The Great American Desert

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Long ago, the middle of the North American continent was a treeless prairie covered by tall grasses and roaming buffalo. When European settlers came, they called this area the Great American Desert. Today, this "desert" is covered with fields of wheat, corn, and alfalfa made possible by center-pivot irrigation. My grandfather used to sell center-pivot systems and when my family drove to my grandparent's home in Nebraska, we would count how many "sprinklers" were watering each section of land. At the time, I didn't know that this water was being pumped from somethng called the Ogallala Aquifer, a huge underground water supply. Throughout the years, this aquifer has made the Great American Desert one of the best farming areas in the world. Unfortunately, the Ogallala Aquifer's future as a valuable resource is in jeopardy, unless citizens of the Plains states reduce their water consumption.

Background of the Problem

To understand why the problem is important, it is necessary to know some basic facts about the Ogalla Aquifer. This underground reservoir covers 174,000 square miles. According to John Opie, author of Ogallala: Water for a Dry Land, the Ogallala was formed over the course of millions of years as the land flooded, dried out, and flooded again. As centuries passed, glaciers melted, carrying water, silt, and rocks from the Rockies down to the Great Plains to form the Ogalla. Dirt, clay, and rocks accumulated above it so that the waters of the Ogallala can now be reached at depths of 300 feet beneath the surface (29-35). Some people think that the Ogallala is a huge underground lake, but this idea is wrong. As Erla Zwingle puts it, an aquifer such as the Ogallala is like a "gigantic underground sponge"(83). The water fills in the spaces between the sand, silt, clay, and gravel that make up the Ogallala formation. This 1,000 feet; the average thickness, however, is about 200 feet (Zwingle 85). The aquifer reaches its deepest points under the state of Nebraska, which is not surprising because most of the because Ogallala's water lies beneath this state. The rest lies under Colorado, Kansas, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming.

Th Ogallala Aquifer is the largest "underground sponge" in the United States. It contains more that 977 trillion gallons, or three billion acre-feet of water. (An acre-foot is 325,851 gallons, or the amount of water it would take to cover an acre to the depth of one foot.) According to Jack Lewis in the EPA Journal, the water contained in the aquifer is enought to fill Lake Huron pluse one-fifth of Lake Ontario. "If pumped out over the United States," Lexis writes, "the High Plains aquifer would cover all 50 states with one and one-half feet of water."

The Nature and the Extent of the Problem

Each year, at least 7.8 trillion gallons of water are drawn up from the Ogalla Aquifer to irrigate the crops planted on the High Plains. These cros are the main food sourrce for our entire country. Tragically, irrigation is depleting the aquifer faster than it can replenish itself, and that is the problem. In fact, only the tiniest fraction of the water is ever replaced in the Ogallala Aquifer. If the water were ever fully depleted, the aquifer would need 6,000 years to refill naturally (Zwingle 83). The only way the Ogalla can be replenished is by water seeping down through the layers of soil until it reaches the aquifer. This water comes from the small amount of precipitation in the region, as well as from streams, reservoirs, canals, and irrigation (McGuire and Sharpe).

How serious is the problem? Since 1930, the aquifer's water has been reduced by 11 percent (Lewis). The volume of water has decreased because the use of irrigation has increased so much since World War II. In 1949, 2.1 million acres were under irrigation. In 1969, the amount of irrigation land rose to 9.0 million acres; and in 1978, it rose to 13 million acres (McGuire and Sharpe). The land presently under irrigation in the Texas Panhandle alone is equal to the size of New Jersey (Thorpe). All of this land is supplied by irrigation wells, and the number of wells has exploded over the decades-from just 170 in 1930, to more than 150,000 today (Nebel and Wright 279).

The biggest technological advance that has made this irrigation explosion possible is the ceter-pivot irrigation system.

John Opie explains the system:

The center pivot is a 1300-foot-long pipe that

is held eight feet off the ground by a row of seven or more towers on large wheels. Sprinklers are attached at regular intervals along the pipe, pointing up or down. One end of the pipe is set in the middle of a 160-acre quarter section around which the pipe and wheeled towers circle. (146)

The water pumped through the pipe triggers a mechanism that causes the system to roll in a large circle. All of the crops within the circle receive a generous amount of water.

If you were flying over the Great Plains between Minneapolis and Denver in the summertime, you would see thousands of green circles, showing how farmers have irrigated their land. With center-pivot irrigation, crop production on one acre increases 600 to 800 percent compared to dry land farming (Lewis). Today, 15 percent of all of the United State's wheat, corn, and sorghum grows on Ogallala-watered land, and 40 percent of American beef cattle feed on the grain and water of the Ogalla (Nebel and Wright 279).

Center-pivot irrigation, however, has dramatically lowered the aquifer's water level. Even though famers have known for decade that this was happening, they have continued to pump and spray as much water as they felt was necessary. When a drought hit in the mid-1970's, the water level of the Ogallala began to lower drastically in some areas because of overuse and lack of replenishment. In some parts of Texas, water levels dropped as much as 200 feet. Farmesr who lived above shallow parts of the aquifer could not pump enough water for their crops at that time.

What makes the problem worse is that much of the water pumped from the Ogallala has been wasted. With center pivot irrigation, 50 percent of the water evaporates before hitting the ground. Some farmers also overwater their fields, thinking that more water is better. Much of this extra water filters into streams and ends up in the Gulf of Mexico, instead of seeping back into the ground to replenish the aquifer (Sheaffer and Stevens 115).

The problem is not just about wasteful irrigation, however. It is also about resistance to change.



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