For most of his 43 years, John Mass has watched this farming area east of the San Francisco Bay slowly deteriorate, its fish and wildlife diminish as billions of gallons of local freshwater supplies were diverted hundreds of miles south to give life to the rich farms and suburbs of southern California.

Today Mass and his neighbors, along with almost every politician and civic group in Northern California, believe they are fighting a last-ditch battle for survival against the arid but powerful south. The south is pushing a $5 billion project in the state legislature designed to drain still more water from the north, and while the south may lack water, it has the votes.

"This is such a conspiracy it makes OPEC look like kids' stuff. Most of those politicians in Sacramento are little puppets controlled by southern California interests," said the bearded Mass as he drove his pickup across his 1,400 acres of low-lying land in the delta between San Francisco and and Sacramento.

"They know water is more important today in California than oil. That's why they're shoving this project down our throats."

Mass' sentiments are not typical among the northern California legislators who are desperately fighting to stop passage of the multibillion-dollar expansion of the state water project. The legislation calls for the construction of a 43-mile-long peripheral canal, new reservoirs and other improvements designed to tap as much as one million acre feet of water a year from the natural delta supply north of San Francisco and bring it down 500 miles to southern California. An acre foot is 326,000 gallons or enough water to supply a normal family of five for one year.

The fight over the canal has exacerbated intense regional conflict in the state, pitting the interests of the region from San Francisco Bay north to Oregon against the interests of the south from the San Joaquin Valley to the Mexican border.

The history of this nation is the history of north-south conflict, from the location of the U.S. Capital, to the Civil War, to the fierce economic competition between the growing Sun Belt and the declining Frost Belt states.

It is in this tradition that California is undergoing its water war, and like previous north-south conflicts, the federal government will probably have a major role in its resolution.

Despite intense opposition, the peripheral canal is expected to pass the California state legislature next week. But some opponents say they will challenge the project in the courts, and, in the end, ask the federal government to block it on environmental grounds.

To many in the north, which has 70 percent of the state's water but less than a third of its people, the peripheral canal is a crude effort by southerners, particularly in Los Angeles, to wrest away the north's resources.

And to many in the south, the issue is just as crucial. In 1963, the Supreme Court ordered southern California to surrender about 700,000 acre feet of Colorado River water to Arizona. Southern California has, up until now, relied heavily on this water supply, but expects to lose it when a major new project tapping the Colorado for Arizona comes on line in the mid-1980s.

An attempt by Sen. Larry Pressler (R-S.D.) to put the brakes on Garrison, for fear of what it will do to water in his state, was easily defeated.

"We're growing faster than anywhere else in the state, but we're losing all that Colorado water. If we don't bring water in, we'll have big trouble, we'll have more people with less water," said state Sen. Ruben Ayala, the southern California Democrat sponsoring the canal legislation.

"You don't have to be an economist to know that without the water, the economy would go to pot. If we don't win this one, all other issues won't matter because we won't exist."

Ayala says he is certain the canal legislation provides adequate protection for the water of the north although he acknowledges that the legislative majorities from the south could overturn the guarantees at any time.

The northerners think if we have a drought, our people will vote their districts and turn up the faucet and drain them," Ayala said. "It could happen. That's the way our system works."

Hard-headed, sometimes even violent, political confrontation has long characterized the battle over water in California. While most of the population has tended to live close to the coast, most of the available fresh water has come from the High Sierra mountains and the rivers flowing from the mountains into the region around San Francisco.

Almost every city in California has grown by tampering with these streams before they reached the delta, including San Francisco, Oakland and other northern California cities now strongly opposed to the canal. But in this century most of the demand for massive water projects has come from the expanding agricultural areas of the southern San Joaquin Valley and the Los Angeles area.

Without enormous water transfer systems, southern California as an urban metropolis would not exist. In 1960, living off its natural water supply Los Angeles County reached a limit of 170,000 people. It was little more than a dusty cow town with a pleasant climate while San Francisco and farmers in the water-rich north dominated the state.

Los Angeles forever changed that political equation in 1913 when it completed the Owens Valley Aqueduct, an engineering marvel connecting the arid city with the Sierra runoff of an agricultural valley more than 200 miles to the north. For the hapless residents of the Owens Valley it was a disaster that, after several scuffles with the law and an abortive 1924 attempt to seize the canal, left the once, rich farming area a semi-arid wasteland.

But the canal provided Los Angeles with the water for expansion and the population began to double just about every 10 years. By 1930, San Francisco and the north were losing their majorities in Sacramento -- majorities they had enjoyed since the state's founding in 1850.

Over the last 50 years southern California and the allied San Joaquin Valley farming interests have succeeded in expanding their claim to state water supplies. In 1941, the newly formed Metropolitan Water District, which served southern California, and the federal government completed a canal bringing Colorado River water 242 miles across the desert to Los Angeles.

During the same era, the federal government began work on the Central Valley Project, which took water from the northern rivers and the delta for the benefit of agriculture in the fertile but dry valley areas, turning thousands of acres of scrub land into rich farms.

In 1960 yet another water development plan, the State Water Project, was promoted by then Gov. Edmund G. (Pat) Brown Sr., and passed by a narrow majority of the voters. By 1970 the new state aqueduct was bringing water from the far north into southern California.

This latest transfusion brought hundreds of thousands of new acres of farmland into production. It also continued to help provide for the growing needs of the southern California metropolitan region whose population contains about 12 million of the state's 22 million people.

Virtually from the inception of the California water project, the peripheral canal has been seen as a sort of "missing link" that would ultimately complete the massive water scheme. Among its strongest advocates are the valley farming interests who expanded their acreages in full expectation of the canal's completion.

Without the canal, valley interests argue, the state will never be able to come close to fulfilling promises they made more than a decade ago.

"The canal is absolutely essential," said Assemblyman Richard Lehman, whose family has farmed in the valley for more than 70 years. "There's an obligation of the state to finish the water project. The whole history of progress in this state is the transfer of water to develop a viable economy."

Lehman's constituents, mostly small and medium-sized family farmers, are joined in their advocacy of the canal by corporate agribusiness interests, including Teneco, Getty Oil and Union Oil.

But most observers believe the most potent forces behind the new water project are the corporate and real estate interests concentrated in Los Angeles and nearby metropolitan areas.

James Dickason, chairman of the board of the New Hall Land and Farming Co. and head of the water committee of the elite California Business Round Table, claims the canal is essential to the economic future of the metropolis.

"The canal will make development possible," said Dickason, whose company owns more than 140,000 acres of prime southern California land, much of it still largely undeveloped. "If you don't have water, you can't build."

Such talk has led normally moderate northerners like Republican state Sen. John Nejedly to suggest the canal is little more than a scheme benefiting developers in the south.

Outnumbered, Nejedly and other northern legislators have looked toward Gov. Jerry Brown for assistance in at least mitigating the adverse effects of the canal. They have sought to control how much well water agricultural interests could use, the imposition of strict water conservation measures and guarantees preventing further damming of the last remaining free-flowing rivers in the far north country.

Brown, while maintaining his support for the canal -- the culmination of his father's biggest dream -- won legislative approval in June for a measure perserving the north coast's rivers and locking delta water quality guarantees into the constitution. This amendment will be voted on by the general electorate this fall.

While most northern legislators supported the constitutional amendment, few say it as much more than a face-saving device for Brown, whose political stock has fallen following his humiliating setbacks during this spring's presidential primaries. They point out that the governor has so far been unsuccessful in pushing for water conservation and ground water management legislation to mitigate the south's future demands for water.

Gray Davis, chief of staff for the embattled governor, claims Brown has not received sufficient credit for his attempts to balance the heated regional interests doing battle in Sacramento. "You can see more games played on this issue than at a carnival," Davis said. "The fact is, without Jerry, the north would have had the canal and nothing else."

Most northerners, however, are placing their hopes not on Brown's ability to soften the canal's impact but on legal action and possible intervention from the federal government.Environmental groups, spearheaded by the Environmental Defense Fund, are expected to challenge the canal on numerous environmental grounds.

In addition, the Interior Department appears likely to submit the project to intense scrutiny. The department has already stated is disinclination to get involved as a participant in the canal, as was once expected, and Interior Secretary Cecil Andrus, on a recent visit to California, has publicly called the canal a "pipe dream."