The cattle feeding industry exists on the Great Plains for one reason: the Ogallala Aquifer. But that reason is slowly being used up.

The Ogallala isn't like a reservoir that refills with spring rains. The aquifer recharges slowly - very slowly - as winter snow melts and rain seeps into the ground. Twentieth century agriculture uses the aquifer's water much faster than it refills to supply the needs of the grain and cattle feeding industries. Agribusiness realized decades ago that the aquifer wasn't going to last forever.

As ground water supplies fell, a remarkable transformation took place. Cattle feeders, grain farmers and residents converted to avid water conservationists to make their aquifer last as long as possible. Someareas served by the Ogallala now consume only a third of the water they did just a few decades ago.

To glimpse what has happened, look at southwest Kansas, where new wells are banned in areas where the aquifer is overtaxed. Or travel to the Texas Panhandle where aircraft seed the clouds each year, hoping to increase rainfall and ease demands on the Ogallala.

Throughout the region, efforts are underway to find more efficient irrigation methods or develop new irrigation equipment that uses less water. These efforts have met with considerable success. One example is the development of irrigation equipment which delivers water closer to the ground, minimizing losses to wind and evaporation, says Leon New, an irrigation engineer at Texas A&M Extension. New and others jointly developed the device.

And in laboratories around the country, crop scientists are seeking to create the grains of the future - plants which use less water to produce yields equal to today's crops.

The goal of these efforts is to maintain the economic vitality of the Great Plains by making the water last. After all, water, not oil, may be the region's most valued asset. "The oil isn't going to do us any good if we don't have water," says New.

Despite these efforts, the water is still being used faster than nature can replenish it and agribusiness continues to search for more ways to use less. But nobody knows whether the Ogallala can be made to last indefinitely, or whether it will finally begin to fall victim to the laws of supply and demand.

"How long will it last?" asks Ginny McGuire, a hydrologist with the U.S. Geological Survey. "That's hard to say because as the water level goes down, you get more regulation and more conservation technology, so you use less. As the water level goes down, people's behavior changes."

Aquifer's Formation The Ogallala owes its existence to the Rocky Mountains. As erosion wore down the Rockies millions of years ago, rain washed bits of sand and gravel eastward across the Great Plains. Over time, the sediments grew thicker, forming something like an immense sandbox with a clay liner at the bottom which prevents water from escaping.

Gradually, water filled the gaps between the sand, creating a very large, high-quality supply. For most of the Ogallala's history, no one tapped that supply. Although permanent settlement began in the late 19th century, early arrivals thought the region was unsuitable for agriculture or grazing. The Great Plains were marked by drought, insect infestations, fires and a scarcity of surface water. It didn't rain enough to make dry land farming worthwhile.

>From the late 1950s on, a series of innovations in irrigation technology >opened the Great Plains to high-yield farming. These innovations made >irrigation easier, more efficient and more effective. As growers seized on >the new technology, they sucked huge volumes from the ground each year, >turning the one-time dust bowl into the nation's grain belt.

Cattle feeders followed the grain boom, building giant feedyards up and down the 174,000 square miles served by the Ogallala - a region that starts in Nebraska, runs south through Colorado, Kansas and Oklahoma, then winds up in the Texas Panhandle.

"There was this huge abundance of corn and alfalfa," says Hank Hansen, who advises cattle feeders and farmers on water rights in the Southwest Kansas Ground Water Management District. "The feeders saw that potential and said rather than shipping the grain, why not feed the cattle here?"

Feedlots now depend on the Ogallala in two ways. The aquifer is the backbone of the grain belt which in turn serves the feeding industry. But feedlots also depend on the aquifer directly because cattle require a lot of water.

But there was a price for this new prosperity. The aquifer was emptying at an alarming rate.

On a percentage basis, grain farming is the biggest guzzler of water from the Ogallala. Farming accounts for more than 90% of all water used. Feedlots, on the other hand, account for just a few percentage points.

But that few percentage points still adds up to a lot of water.

Since feedlot cattle use an average of about 12.5 gal./day, a 50,000-head lot would use more than 600,000 gal./day. That puts a heavy burden on the underground supplies serving the lot.

As the aquifer is used up, the feeding industry will feel the pressure two ways. Indirectly, feeders will feel the pinch if local grain production falls for lack of sufficient water. But, feeders will feel pressure directly because they can't operate without a lot of water.

Commitment To Conservation Over time, conservation fever has caught hold. While no single water-saving measure did the trick, small improvements added up and water use fell dramatically.

For example, in the 1960s and 1970s, The High Plains Underground Water District in Lubbock, TX, depleted the aquifer by roughly 1.4 million acre feet of water per year. Now, the annual depletion rate is down to about 500,000 million acre feet per year. "We've cut it to about a third of what it was," says Wayne Wyatt, the district's general manager.

"There's a lot of difference between what's happening now and what happened in the early days of irrigation," he says. Back then, water was funneled down an irrigation ditch, then poured down furrows in the fields. "The effective use of water was probably no more than 50 percent of what was pumped. The losses where the best technology is used now are probably about five percent of what's pumped."

The original predictions were that we would be out of water by now, says Ben Weinheimer, regulatory manager for the Texas Cattle Feeders Association. "Obviously we're not. That's primarily because of water conservation.

"The efforts to conserve water over the last 20 years have shown us that we can help in extending the life of the aquifer," he adds. "If it's done properly, we'll have the use of the aquifer for many generations to come."

Conservation saves water, but it doesn't add any. Cloud seeding, on the other hand, may bring rain and extend the life of the Great Plains water supply.

"If we can get a little more water out of the sky, it reduces the amount of water we need to pump," says Wayne Wyatt, general manager of the High Plains Underground Water District in Lubbock, TX.

Last year, the High Plains district turned to cloud seeding after reviewing the success of another Texas district which has been seeding clouds for 20 years. "They've had very significant increases in precipitation," says Wyatt. "In targeted areas, they're showing increases of 40 percent.

"Last year was the first time we did it," he says. "One year's result is not enough to make a broad statement about how good it works. We did receive above-average rainfall, but there are a lot of areas in the state of Texas that received above-average rainfall."

Cloud seeding works on basic chemistry. Pilots drop silver iodide flares at an altitude of 16,000-24,000 ft. When the flares burn, they release tiny charged particles which attract water droplets of the opposite charge. When the droplets get large enough, they become heavy and fall from the sky as rain.

But first you need clouds. The High Plains District meteorologist scouts local weather conditions, making sure conditions are right before he orders pilots to seed selected targets within the 10 million acres of Texas and New Mexico covered by the project. Preference goes to areas which have had the least rainfall in the previous ten days.

The cost is nominal when spread over millions of acres. "It costs about 5 cents an acre, or about $500,000," Wyatt says.

When it rains, everyone wins. It not only takes pressure off the aquifer, but also increases the recharge rate of the aquifer, adds Wyatt. "We get more runoff into reservoirs for municipal water supplies. We've got a lot of dry land farming. It helps them, too."