WATER, a finite resource without a substitute, is being fought over by farmers, environmentalists, industries, and cities in an increasing number of regions of the United States.
Politicians caught in the fray tend to focus on medium-term solutions: conservation, construction of new reservoirs, or acquisition of water rights. But some observers argue that only controls on population growth will prevent demand from overwhelming water supplies in the long term.
Such controls seem farfetched now, these observers admit. But they note that President Clinton has reversed the stance of the Reagan and Bush administrations against allowing federally funded health clinics to discuss abortion and against funding United Nations programs that promote family planning.
A current US battleground over water is central Texas, where 1.5 million people pump all their water from the Edwards aquifer. At best, users say, current demand on the Edwards is roughly in balance with its supply.
A recent two-year drought was enough of a close call to prompt a lawsuit that could bring restrictions on pumping from the Edwards. That case is pending in federal court. Ground water `sacred'
Meanwhile, legislators are struggling to produce plans to regulate the aquifer - unprecedented in a state where "ground water is more sacred than whiskey or shooting," says Helen Dey, a legislative aide working on the issue.
Parties to the struggle for the Edwards include:
* Downstream interests. The Edwards feeds the Comal and San Marcos springs, home to plants, fish, and salamanders on the federal endangered species list. Those springs contribute to the Blanco and Guadelupe rivers, on which farmers, towns, and industries downstream rely. And the freshwater input from the Guadelupe is essential to its coastal estuary, where shrimp and many species of commercially valuable fish hatch.
* Farmers on the western edge of the Edwards. They say any plan that limits pumping or attaches fees could put them out of business. "Excuse me for sounding so sarcastic," says Luana Buckner, general manager of the Medina County Underground Water Conservation District, "but we're out here fighting for our lives against a salamander that has the federal government on its side."
* San Antonio. By one projection, the city's population will double to 2.4 million by 2040. So far, San Antonio has relied on its right as a landowner above the Edwards to pump as much as it wants. The city charges one of the lowest water rates in Texas to residents, who use half or more of their supply to irrigate an estimated 60,000 acres of St. Augustine lawns.
City officials and state representatives from San Antonio now admit their need to develop other supplies. But first, they say, a higher authority will have to restrict the city's use of the Edwards because San Antonio lacks the political will to do so itself. In 1991, residents voted to halt a $150 million project that would have met some of their needs with surface water. Signs of overtaxing
By one measure, the Edwards is far overtaxed already - in order to guarantee the flow from the Comal and San Marcos springs during an extreme drought, pumping from the Edwards would need to be reduced by 60 percent, says Tony Bagwell, assistant director of planning at the Texas Water Development Board (TWDB). The TWDB, a planning and forecasting agency that lacks regulatory powers, was created in 1957 after a six-year drought caused 94 percent of Texas counties to be declared disaster areas.
And tight supplies of water loom in the 21st century for other regions of Texas.
The TWDB expects the state's population to double by 2040. Those 35 million people, the TWDB says, will have just enough water, if aggressive conservation begins and $39 billion is spent to build reservoirs at the most feasible remaining sites, as the TWDB recommends.
Finding new water supplies is "always the first reaction" of people faced with a shortage, comments Charles Wilkinson, a University of Colorado law professor and water-rights expert. "Then, a generation later you're in exactly the same place," he says, citing the history of Phoenix.
Furthermore, some of TWDB's proposed reservoirs are "pipedreams," Ms. Dey and others say. Landowners will resist having land taken for reservoirs.
Ken Fredrick, a senior fellow at Resources for the Future, adds that the public places a far higher value on leaving rivers in their natural, flowing state than it did just 30 years ago. Thus, reservoir projects will also meet stiff opposition on environmental grounds.
Water conservation could do much more to stretch supplies, Mr. Fredrick says. A start would be to charge users the replacement cost for water, not just its production and treatment cost, Mr. Bagwell adds.
In San Antonio, water rates are low because "it's easily available," shrugs John Boggess, a spokesman for the San Antonio Water System.
One approach to balancing supply and demand - somehow limiting the population - is unthinkable for now. "When you talk about controlling population growth in this country, you're talking about sex, religion, and politics. You've got to tread slowly," says Dianne Sherman, a spokeswoman for the advocacy organization Zero Population Growth.
But increasing evidence of water scarcity, Professor Wilkinson says, has already prompted the stirrings of what he expects to be a generations-long debate that could lead to the political will to curb population growth.
In Texas, Dey says, "population is going to be our biggest environmental challenge." Bigger population seen
Long-term population trends are difficult to project. For instance, in 1989 the Census Bureau predicted that the US population would peak at 304 million in 2038 and then decline.
But the bureau recently threw out a key assumption - that growth rates for minorities would slow to the same rate as for non-Hispanic whites. There was "no clear evidence of convergence," says Gregory Spencer, chief of the population projection branch.
Last December the bureau changed its projection for 2050 to 383 million persons - and rising.