Great divide between water-rich North, arid South. (A Special Report: L.A.'s Search for Water).

FOR decades, mentioning water in California meant igniting a civil war between the northern and southern parts of the state. And for good reason: two-thirds of the precipitation falls in the less-populated north, while two-thirds of the people who need that water live in the south.

But in recent years, the dividing lines have become more fractured as the state's population grows. Nowadays, it's urban and rural interests pitted against each other--even in the same general region.

"What's happening is that each county is increasingly a mosaic of the entire state," said State Librarian Kevin Starr, who also teaches a course on California at the University of Southern California's School of Policy, Planning and Development. "It means you can't demonize people in whole sections of the state now."

Environmental considerations also have complicated the water wars. Environmental groups have pushed for increasing water set-asides to protect wildlife habitats and have been the driving force behind endangered and threatened species listings like the Pacific salmon and the Delta smelt. Those listings have led to strict rules on how much water can be taken out of a given area.

This has resulted in what became known in the 1990s as the "three-legged stool" of water interests: urban water users, farmers and environmentalists.

"You still have the city folks against the farmers," said Stephen Erie, a professor of political science at the University of California San Diego. "But now you have the environmentalists against both the urban water users and the farmers."

The old days

The original north-south conflict was epitomized in a ballot-box battle 20 years ago over the so-called Peripheral Canal. This proposal, years in the making, called for a canal to be built around the troubled San Francisco Bay Sacramento River Delta region, greatly reducing the cost of transporting water from the north to the south.

In one of the bitterest initiative campaigns in California history, opinions were sharply polarized in the north and south. On election day, the measure received overwhelming 70 percent support in southern cities like San Diego. But Northern Californians turned out in huge numbers, with a whopping 90 percent voting "no." The measure lost by a 3-to-2 margin.

"Northern Californians always believed it's their water and they want to keep it in the north," said Erie. "Southern California, which has seen all this tremendous growth, has been driven by the overwhelming imperative of ensuring it has enough water."

The 1994 Bay-Delta accord between then Gov. Pete Wilson and then U.S. Interior Secretary Bruce Babbitt established a truce in the regional war. That accord set up the Calfed consortium of state and federal agencies to come up with a plan to restore the Bay-Delta and maintain a habitat for threatened and endangered species.

But the sides haven't vanished; they've simply put their differences aside temporarily. If the Calfed process doesn't receive the funding it needs this fall from the federal government and California voters, there's fear that the tenuous alliance will begin to dissolve.

Meanwhile, the north-south split hasn't gone away either. Three years ago, when talk of another "peripheral canal" surfaced as a way to bypass all the problems in the Bay-Delta area, a brief but very vocal uproar in Northern California forced the Calfed consortium to drop the idea.

The north-south divide may be emerging again as an issue in the debate over a $3.4 billion bond measure slated for the Nov. 5 ballot. The bond sets aside $825 million for fixes to the Bay-Delta and is strongly backed by Southern California water interests, who may find themselves increasingly dependent on water from northern California as they are forced to lessen their dependence on Colorado River water.

"We strongly support the measure and will do everything we can to make sure that it passes" said Rusty Hammer, president and chief executive of the L.A. Area Chamber of Commerce.

But the state Chamber of Commerce has not yet taken a position on the bond measure. Sources say one reason is that several major Northern California water users fear it might lead to diversion of water from the north to the south.

"These water users say there's not enough money in the bond measure for storage facilities in Northern California, so that any fix to the Bay-Delta will simply send more water down south:' one source said.

Given that fixing the Bay-Delta is one of the state Chamber's top priorities for ensuring adequate water supplies, it's unlikely that the Chamber would oppose the measure outright. But it's possible the state Chamber could take a neutral stance, a markedly different position than the strong support from the L.A. chamber.

RELATED ARTICLE: Sides in the Water War

* Northern California--Blessed by two-thirds of the state's total precipitation, Northern Californians have fought bitterly to keep the water in the north.

* Southern California--Confronted with an ever-expanding population, leaders in the area helped push the massive State Water Project through to completion, but were stymied 20 years ago with the defeat of the Peripheral Canal proposition.

* Urban Users--Once largely confined to the coastal cities, urban water users are sprouting up in virtually every California county as farmland is converted into housing tracts. Al those houses need water.

* Agriculture--Increasingly dominated by big agribusiness firms, California's farmers, although small in number, account for more than 70 percent of the state's water demand. Agribusiness firms in the Central Valley have been fighting to retain federal subsidies that allow them to buy water at lower-than-market prices.

* Environmentalists--Barely a force in water wars 25 years ago, these groups now wield tremendous influence. They have successfully pressured federal and state officials to list several species as threatened and endangered.