Fighting a fierce north wind and cresting waves, a dozen Cucapa Indian fishermen were in trouble before they were halfway home, their small boats and balky outboard motors overmatched by the roiling estuary of the Colorado River Delta.

“Malo viento,” muttered Julio Figueroa, as he nosed his boat slowly through the wind-whipped waves, his feet submerged in 10 inches of standing water. Boats have capsized and men have drowned in these waters, where river and sea collide. Many others have drifted out to sea after waterlogged motors stalled.

The Cucapa say that every year they must venture farther downstream, braving some of the highest spring tides in the world. Rough seas aren’t the only hazard. It is illegal to fish here. The waters are part of a federal sanctuary created to protect several imperiled marine species. Although getting caught could cost them their boats, the Cucapa say they have little choice. Upstream, where the current is slower and the fishing legal, there is not enough water anymore and, consequently, not enough fish.

FOR THE RECORD: An earlier online version of this report said the Colorado River traverses seven of the most arid U.S. states. It provides water for seven of the most arid U.S. states.

As U.S. scientists warn of a semi-permanent drought along the taxed river by midcentury, Mexico today offers a glimpse of what dry times can be like. Rationing is in effect in some areas. Farmers have abandoned crops they can no longer irrigate. Experts fear that the desert will reclaim some of the region’s most fertile land.

The Cucapa are a tiny portion of the 3 million people in northern Mexico who depend on a meager allotment of Colorado River water that was not enough when it was granted by treaty in 1944, and is far from enough now. Traversing 1,440 miles and providing water for seven of the most arid U.S. states, the Colorado River arrives here as an intermittent stream laden with sewage, fertilizer, pesticides and salts leached from farmland.

The Cucapa and their ancestors have been living in the Colorado River Delta for 1,000 years, sustaining themselves on what once were lush wetlands. As the river and its surroundings dried up, most of the Cucapa went elsewhere. Today, the handful who remain -- fewer than 200 -- cling to a water-starved environment that is as imperiled as they are.

Every year at this time, the Cucapa head for the “zono nucleo,” the core of the marine reserve where the river meets the Gulf of California. Playing cat and mouse with police patrols, the Indians net corvina, a commercially popular fish that can bring them as much money in a month as they can earn in a year working in fields or doing other manual labor.

This spring day, the Cucapa fishermen would have had unusually good luck if the weather hadn’t turned against them. The corvina were plentiful and the patrols nowhere in sight. But the wind didn’t let up, and by midafternoon many of the overloaded Cucapa boats were riding precariously low in the choppy water.

As they retreated upriver, one boat lodged on a sandbar, forcing its crew to dump a third of its catch before the men could free their boat. Then another boat -- with Figueroa’s stepson aboard -- began to go down, its bow slowly submerging as the two-man crew yelled for help and the pilot frantically tried to guide the boat to shore before the motor gave out.

The men on the stricken boat were eventually rescued, though Figueroa was powerless to help, as he would have had to turn his own heavily laden boat broadside to the waves and almost surely capsized. Nor could he ignore the rapidly receding tide, which could strand him on the riverbed far from home.

One hundred years ago, 30-ton steamboats made their way up the mouth of the Colorado. Now, at low tide, there is no longer enough water flowing downriver to float the Cucapa’s 20-foot-long pangas and their cargo. For all his hard work, Figueroa ended the day mired in the nearly dry riverbed, a mile short of his destination, his fish losing much of their freshness and value.

“Malo viento,” he kept saying. But it was the river, not an “evil wind,” that had let him down.

Dams, drought, climate change, urban growth, industrial agriculture and politics on both sides of the border are to blame, and none of those adverse conditions will reverse any time soon.

Reservoirs have been drawn down to historically low levels, and some scientists predict that under the influence of climate change, the river’s annual flow could drop by 50% over the next 40 years.

Despite heavy snowfall in the central Rocky Mountains this year, river managers in the U.S. continue to advise the states that depend on the Colorado River to prepare for water shortages within five years.

Measures to shore up U.S. reserves, meanwhile, are likely to make water even more scarce in Mexico.

For many years, Mexico has benefited from an unofficial surplus over its meager original allotment of river flow. The extra water comes from a combination of underground seepage from an unlined diversion canal in California, and storm runoff that makes its way south of the border.

The U.S. is in the process of stanching the fugitive flow by lining much of the All American Canal, a 90-mile-long irrigation ditch in California’s Imperial Valley. Plans also are underway to build a small reservoir to catch 60% to 70% of the surplus surface water before it reaches Mexico.

The extra water has been a boon to crops in the arid Mexicali Valley and a godsend to the Colorado River Delta, where the Cucapa and hundreds of other poor fishermen eke out a living. Marine biologists believe that the corvina and other fish rebounded from the brink of extinction largely as a result of periodic high flows that flushed through the mouth of the river.

“To the extent it survives at all, the environment down there lives off the slop, off unplanned releases,” said Peter Culp, a water lawyer and consultant to the Tucson-based Sonoran Institute, a nonprofit group that has been working on delta restoration.

Without the surplus, farmers in the Mexicali Valley say they will have to fallow land, cut their workforce and rely on aquifers that are already being pumped at an unsustainable rate.

“Some people will be put out of work. Others will have to reduce their standard of living,” said Leopoldo Hurtado, who farms 40 acres south of Los Algodones, near the border. “We will have to pay to dig deeper wells and raise fewer crops.”

A recent study published by San Diego State University estimates that the production of some fruits and vegetables in the Mexicali Valley will drop by more than half over the next 20 years. More than 7,000 farm families could lose their livelihoods, according to Mexicali economist Enrique Rovirosa.

For much of northern Mexico, the only supplement to the Colorado River is groundwater. But in a desert region that receives about 3 inches of rainfall a year, overdrafting is a perennial danger. Millions of acres of farmland across northern Sonora and the delta have already been abandoned because groundwater supplies were exhausted, according to a report in Earthscape, an online journal of natural resources sponsored by Columbia University.

The same thing may be happening in northern Baja’s Guadalupe Valley, one of Mexico’s most productive winemaking regions. “The symptoms of desertification are undeniable,” said Antonio Badan, a local vintner and an oceanographer at CICESE, Mexico’s Center for Scientific Research and Higher Education. “Olive trees and carob trees are dying. The tomato farms are gone. Four of my five wells are dry. We are clearly on a collision course with a catastrophe.”

More to the point, the Guadalupe Valley is on a collision course with Ensenada, the fast-growing Pacific Coast city to the south. Ensenada was supposed to get much of its water from the Colorado River, but the necessary pipeline was never built. So the city receives its share indirectly, through a groundwater exchange with Tijuana, which does have a pipeline to the Colorado.

But Ensenada, like much of northern Mexico, has outgrown its allocation. The city now draws water from other sources, including the deep wells that Badan and his neighbors say are draining the Guadalupe Valley’s aquifer.

Even with those, about 20% of the city’s population of 413,000 does not receive water regularly, according to Rogelio Vasquez, a water expert who heads the department of applied geophysics at CICESE.

Vasquez and other experts believe it will take close to $1 billion to develop an adequate water supply by building a desalination plant, repairing and expanding pipelines, and capturing and recycling runoff.

In the meantime, he said, some people will continue to do without.

“Crops will suffer,” he said. “Costs will go up and tensions will rise.”

Across the city, shiny black and blue barrels dot the rooftops of new housing developments, barrels in which residents store water for use when none is flowing through their faucets. Often, the shutdowns last days.

In Lomas de la Presa, a middle-class neighborhood where some houses cost the equivalent of $40,000, resident Raul Natzu said the water flows about four hours a day. “There’s enough for essential uses, but no water for flowers or anything outside.”

In ramshackle neighborhoods like Puesta del Sol, where people erect makeshift dwellings from plywood, cinder blocks and surplus garage doors, water doesn’t flow at all. Instead, residents buy what they can afford from roving trucks. They store the water in rain barrels and dole it out as needed to bathe, flush toilets, and wash dishes and clothes.

Agustin Galindo, a 35-year-old unemployed parking lot attendant, said that he, his wife and their three children have gone without water for as long as a week during periods of unemployment. “I don’t have water because I can’t afford water,” he said from his two-room house flanked by empty rain barrels.

At the present rate of consumption, Ensenada’s demand for water will be double the supply by 2035, according to Vasquez. “That assumes a steady state of supply,” he said. “But the supply isn’t steady.” The water levels in municipal wells are dropping an average of 59 feet a year, he said.

Cross-border feud

There is still much bitterness between Mexico and the U.S. over Colorado River water, which was allotted grudgingly in 1944, after the Mexican government threatened to cut off water vital to agriculture in the Rio Grande Valley of Texas.

That treaty gave Mexico about 10% of the Colorado’s estimated annual flow, about half of what Mexico wanted and not nearly enough to support the ensuing population boom. Only a few hundred thousand people were living in northern Mexico at the time, compared with the 3 million there now.

Over time, Mexico came to believe it was entitled to the surplus flows, so when the U.S. announced its intention to capture most of the surplus, a coalition of growers and Mexican officials sued. The U.S. Congress essentially mooted the case by exempting the water capture from all federal laws, including the National Environmental Policy Act, invoked by the plaintiffs.

Outraged Mexican officials accused the U.S. of stealing water from the poor to fuel the growth of fancy suburbs in San Diego and Las Vegas, where much of the water is destined to go.

“The U.S. has contravened its obligations once again so that it can get more water flowing to its swimming pools and flower gardens,” said Alberto Szekely, a career ambassador with the Mexican Foreign Service and an expert on cross-border environmental issues.

U.S. officials said they spent three years trying to work out a compromise that would allow Mexico to continue receiving some water from the All American Canal. They said those efforts collapsed when Mexico filed suit.

Even the harshest critics of U.S. water policy acknowledge that Mexico bears some responsibility for the worsening water crisis. Urban growth has outstripped pipelines that lose as much as 50% of the water they carry, according to officials of Conagua, Mexico’s national water commission.

“There’s no question Mexico has been delinquent in some respects,” said Szekely.

Mexico also apportioned its share of the river to urban and rural users, leaving the delta with nothing. The Cucapa, who have lived in northern Mexico longer than anyone, were not consulted.

Shortly after construction of Arizona’s Glen Canyon Dam in 1963, the delta dried up. What once was North America’s largest desert estuary, a marshland larger than Rhode Island, shriveled to 10% of its original size, replaced by miles of salt-encrusted mud flats.

By the mid-1980s, two dozen species of fish were headed for extinction and 60 more were at risk. A total collapse of the fishery was averted only by several years of high river flows, the result of heavy snowfall upstream in the Rocky Mountains.

In 1993, the Mexican government, under pressure from environmentalists around the world, created a 3,000-square-mile reserve, its boundaries extending from the delta well out into the Sea of Cortez. Its nucleus at the mouth of the river was made off-limits to commercial fishing.

Jose Campoy, the director of the reserve, said the ban on fishing in the core, along with the periodic high flows down the river, is responsible for the resurgence of the corvina population.

But the ban does not deter everyone.

“There have been a lot of fines. But it is impossible to keep them away,” he said of the Cucapa fishermen.

Last weekend, federal authorities seized about 9 tons of corvina allegedly caught out of season and in the protected zone by members of a Cucapa fishing cooperative.

“It’s a lousy situation,” said Andres Lopez, a Cucapa fisherman. “But you gotta eat.”