Third-generation farmer Gary Arnold has a clear view of the Rio Grande from his home northwest of Las Cruces. "I live right on the river. I've watched it for 50 years," he says. "If you look around, it's all desert, except for this beautiful, green ribbon. The only reason it's green is there's water down there."

Arnold, a pecan grower and chairman of the board for the Elephant Butte Irrigation District (EBID), takes a more careful look than most. He can see inevitable changes coming as the region's population continues to grow, creating new municipal and industrial demands for water.

"Health of the river is critical to the health of the region," Arnold says. Though it's no mighty Mississippi, the Rio Grande ranks as North America's fifth-longest river, flowing 1,800 miles from headwaters in Colorado's San Juan Valley to the Gulf of Mexico. After bisecting New Mexico, it forms an 800-mile international border between Texas and Mexico.

As early as 200 B.C., people settled in the lower Rio Grande Valley and used the river to water their crops. Around A.D. 300, Pueblo Indians further north on the river and its tributaries used methods that evolved into the irrigated agricultural practices used today.

"The Pueblo Indians started irrigation, the Spaniards adapted that into acequias, and Elephant Butte Irrigation District was adapted from that," says Gary Esslinger, EBID manager and treasurer.

The modern-day impetus for the district came from Mesilla Valley farmers who dug canals and diverted the river in the mid-1800s to supply the growing agricultural sector. Though many of the farmers' structures crumbled, their experience provided important lessons for Bureau of Reclamation construction of dams, canals and drains that started in the early 1900s.

To secure a reliable water supply for their crops, farmers were willing to take out liens on their property to open and drain valley lands, and to pay the construction bills for their share of the large-scale reclamation project. In 1918, EBID was created to oversee irrigation downstream from Elephant Butte Dam in New Mexico.

The irrigation district is a quasi-governmental agency and, like a municipality, it has the authority to borrow money and to issue bonds. EBID can transfer the right to use district water without approval from the state engineer. The state Depart-ment of Finance and Administration must approve EBID's budget each year. The district's construction debt to the Bureau of Reclamation was paid off in 1972, and in 1994, EBID became the first irrigation district in the West to obtain a federal land transfer back from the Bureau of Reclamation.

Like its Spanish predecessors, EBID's irrigation is a gravity-fed system made possible by the drop in elevation from north to south in the Hatch, Rincon and Mesilla valleys. The system has three dams-Percha, Leasburg and Mesilla-that divert water into main irrigation canals and into a network of lateral canals and drains.

Manager Gary Esslinger's history with EBID goes back 20 years-20 of the wettest years in its history, he is quick to point out. "When I started back in 1978, the annual water allotment was only 9 inches per acre, versus 3 acre-feet today." he says. (An acre-foot is the amount of water needed to cover one acre 1 foot deep.)

Esslinger, who jokes that he is EBID's "water boy," does not expect the wet cycle to last. During the worst drought in the project's history, between 1950 and 1958, Elephant Butte reservoir dropped from its storage of 2 million acre-feet to less than 50,000 acre-feet. "Fish were dying," Esslinger says.

No one knows when the region's drought-prone history will repeat.

Today, EBID has 7,000 accounts for the relatively cheap surface water supply available through the district. About half of these users have less than 2 acres of land and receive water deliveries every three weeks during the irrigation season. The district includes 133,000 acres, 90,640 of which have water rights and can be irrigated from the canal system. About 8,000 acres are planted and harvested twice each year.

However, even in good years, the EBID allotment is not enough to raise many crops. About 60 percent of the valley's crops require more than 3 acre-feet of water, including chile, pecans, onions and alfalfa. It's common for growers to supplement their surface water supply with 1 to 2 acre-feet of groundwater from wells each season. Groundwater also allows needed flexibility in watering crops.

Because the river recharges the aquifer system and the groundwater discharges back into the Rio Grande, surface and groundwater are inextricably linked. EBID's 400-mile drain network carries away salts leached from the farm soils. In places, the drains extend 30 feet deep, reaching the water table.

"What makes this valley whole is the connection between groundwater and surface water," Esslinger says. "You have to keep the system in balance. If you pump water out from beneath us, it affects the river."

In recognition of this fact, there is speculation that the state engineer will require a well-monitoring and metering program, and possibly call for a plan to make well water the primary irrigation source for some farms where surface water is viewed as the supplemental supply, says John Hernandez, an NMSU professor of civil engineering and long-standing expert on the hydrology of the Rio Grande.

An adjudication of the right to use water in the Lower Rio Grande has been ongoing in district court for the past three years, he says. There is the possibility of a strict adherence to a duty of water of just 3 acre-feet-from both surface and groundwater sources. If the supply is limited to 3 acre-feet, it could change the complexion of Mesilla Valley agriculture considerably, Hernandez says. There is speculation that the state engineer may recommend that allotments be adjusted according to crop, he adds.

Five years ago, Robert Faubion invested in a drip irrigation system for 150 acres of less-productive, sandy land where he grows corn, chile and cotton. Though the equipment was costly, he hoped to economize by using less of his surface water allotment. His plan worked well the first year until the summer monsoon season in July and August, when the filtration system couldn't handle the sediment in the surface water.

After that, Faubion switched to well water and relocated his drip system, with good results. "Cotton never averaged 2 bales per acre before," he says. "Now, it averages 3 bales per acre with a drip system."

While increasing yields, Faubion also has cut his water use in half. Chile normally requires more than 48 inches of water. With drip irrigation buried a foot under the seed-bed, Faubion needs only 24 inches of water. Though he waters much more frequently, he uses smaller amounts, relying on NMSU information about evapotranspiration rates. He expects the drip-irrigation tape to last for approximately 15 years, though he did have to buy special tillage equipment for the system.

Still, Faubion doesn't expect many other growers to follow his lead in converting to drip irrigation. He estimates his conversion costs at $1,500 per acre, too expensive to compete with cheap surface water flowing down the ditches.

Faubion has left the ditches intact on the drip-irrigated land. He saves $4,000 to $8,000 per year by not having to purchase additional surface water. Faubion believes conservation will have to be market-driven. "Who's going to pay for it otherwise?" he says. "It can't be forced."

What Faubion and other EBID farmers want is a provision in the district court adjudication to allow for voluntary transfer of water rights, so that they can lease or sell their rights to other water users or municipalities. This would give farmers a choice of using the supply or transferring agricultural water to municipal purposes.

A farmer who receives a 6-inch allotment on a 300-acre farm could lease 150 acre-feet to a regional municipality to pay off debts during a drought. In subsequent years, he could use half his water allotment and lease half of it.

Under current law, all water flowing from Elephant Butte reservoir for consumptive use in New Mexico is for agriculture. Under New Mexico water law, the first person to put the water to the highest beneficial use has priority to use the available supply. Water rights holders retain their rights as long as they continue to put it to beneficial use.

However, if a farmer like Faubion practices conservation, nonuse of part of his right is not recognized as a beneficial use.

Many advocate changing the law. Some lawmakers are trying to pass legislation that would provide tax credits for conservation, though farmers like Faubion and Arnold fear credits could easily be revoked.

"There is little question that water conservation technology and the incentive to use it is vital to long-term growth of agriculture and municipalities in the valley," says Ric Frost, an NMSU graduate research specialist with the Range Improve-ment Task Force. Laser leveling, surge irrigation and plant varieties that demand less water are already good steps in that direction, he says. "But these methods cost money to employ and less water-demanding plants are a long way off from mainstream crop use."

Even more readily attainable conservation methods may not be widely applied in the absence of water conservation incentives, says Tim Jones, Agricultural Experiment Station soil scientist.

A little more than half of Elephant Butte water releases go to New Mexico users; the balance is used in Texas. A federal lawsuit is underway to determine the ownership of the water supply of the Rio Grande below Elephant Butte Dam. The U.S. Bureau of Reclamation claims ownership of water below the dam, subject to the interests of the irrigation districts in Texas and New Mexico, and subject to the rights of the farmers who have put water to beneficial use. Under an international treaty, Mexico is entitled to 60,000 acre-feet annually, except during times of extraordinary drought.

"The Rio Grande Compact must be kept intact because without it all uses of water along the river will suffer," says Tom Turney, New Mexico's state engineer. Though it is sometimes criticized, Turney believes the Rio Grande Compact is workable, because it divides available water on a sliding scale between Colorado, Texas and New Mexico. This is superior to the Pecos Compact, which requires a set formulated proportion of the supply to go to Texas regardless of conditions, he says.

In addition to farmers, city planners and wildlife advocates are concerned about water quality. "To improve it, you dilute the water," Esslinger says. Year-round flows in the Rio Grande would enhance the quality available for both drinking water and wildlife watering, he says.

Burgeoning population growth in southern New Mexico and the border region has regional municipalities eyeing EBID as a possible source of drinking water. Kevin Bixby, director of the Southwest Environmental Center, estimates that all the water from the Elephant Butte reservoir could be required to support downriver households of 4.4 million people at conservative use levels in an area, including Juarez, that is projected to have a population of 6 million in 2025.

At the same time, Bixby is considering action to assure that operations in the district comply with requirements of the Endangered Species Act, which may or may not lead to year-round flows of the river.

Records show that consistent year-round flows of the Rio Grande were not pre-dam realities, Hernandez says. "It should be noted that the Rio Grande in the Mesilla Valley is not now the habitat of any listed endangered species."

Year-round flows to maintain water quality make a more compelling argument, Hernandez says. "Water leaving Elephant Butte Dam has dissolved solids of almost 500 parts per million, an acceptable salinity level. During the winter period, without irrigation releases, the dissolved solids in water at the International Dam may reach 1,400 to 1,600 parts per million, making the river too salty to be used as a potable supply in winter."

Las Cruces now gets all of its drinking water from underground wells. However, the city owns farmland 2.5 miles south of Mesilla Dam and has considered the possibility of building a surface water treatment plant within the next 15 years.

Frost says water treatment could be enormously expensive, making it worthwhile to look into methods to minimize saline degradation. Substantial degradation in quality occurs at the point where drains discharge into the river. The many potential sources of salinity between the dam and Texas have never been fully explored, he says, leaving open the possibility of finding means of preventing some of the water supply degradation.

Again, Frost says, technology holds the key to giving the Rio Grande a chance to continue to give to agriculture and to everyone in the valley for generations to come.