THE second-largest nation to emerge from the Soviet Union, seemed to have a better shot at success than most. It is blessed with deep pools of underground oil. Its leader, Nursultan Nazarbayev, gave at least some political space to opponents, independent organizations and a free press.

But in an apparent ambition to become czar for life, Mr. Nazarbayev now seems ready to close that space and squander his nation's advantages. Mr. Nazarbayev, a former Communist Party boss, is the only leader Kazakhstan has known since independence in 1991. Its constitution limits presidents to two terms, but he has found ways to wriggle around such technicalities. The latest trick is to bring forward the scheduled election, from December 2000 to January 1999, and extend the term of the candidate then to be chosen from five years to seven years.

Having accomplished that change, Mr. Nazarbayev now is working to ensure that no one else will have a fair chance to win. Already he controls the broadcast media. Now his government is going after independent newspapers, which have been harassed by tax authorities and deprived of printing presses. The government also has gone after opposition politicians, including the one most likely to offer a serious challenge, a former prime minister named Akezhan Kazhegeldin. The Central Election Committee announced last week that Mr. Kazhegeldin will be barred from running. Why? He addressed an unregistered political organization, was tried in absentia and was fined the equivalent of $80.

The sad thing about this clampdown is that Kazakhstan itself will pay the price. No matter who is in charge, it faces great obstacles: ethnic rivalry between Russians and Kazakhs, geopolitical pressures from surrounding powers, environmental degradation from Soviet times. Dealing with these challenges requires all the talent a young nation can muster. Instead, Mr. Nazarbayev is constricting the base from which leaders might emerge.

And the insidious organization Mr. Kazhegeldin addressed? It was called the Movement for Honest Elections. No wonder authorities had to move in fast.

Monuments to one of history's gravest man-made ecological disasters stand out in sad relief on the coast of what used to be the Aral Sea.

Ships and fishing boats rust on the bottom of dry harbors from which they once plied placid waters. Empty delta tributaries of the Syr Darya River attest to how the rivers that fed the sea have been mortally bled by intensive irrigation projects upstream.

A cemetery at the fishing village of Kareshalan once looked out over reed-filled ponds. Now, salt flats the color of bleached bone provide the vista.

Yet, in the middle of all this -- in fact, in the middle of the Aral Sea -- stand the strangest sights of all. Trucks and bulldozers feverishly tote sand to an eight-mile-long dike designed to save a piece of the sea and bring some life back to a moribund neighborhood.

The Aral Sea saga is reaching a curious climax in Kazakhstan, a central Asian nation that dreams of oil riches but suffers ecological nightmares from its Soviet past. The new dike is meant to permanently separate the Aral's north basin, which is nourished by the Syr Darya River, from the far larger southern section, which was fed by the nearly defunct Amu Darya River in Uzbekistan.

Promoters of the project acknowledge that by damming up the north branch, they condemn the wider lake to accelerated evaporation. But better the survival of the Little Sea, as they call it, than nothing. The Aral Sea is dead. Long live the Little Aral Sea.

The project effectively rejects the notion of saving the whole sea, a war cry of environmental groups around the world. But it is also a reaction to a decade of expressions of concern from officialdom, publicity campaigns, studies and conferences that brought precious little relief.

Kazakhstan's 17 million people are spread across a sprawling territory that touches Russia, China and a cluster of smaller Central Asian nations to the south. It holds potentially large petroleum reserves that, along with nearby Azerbaijan, have made it a magnet for oil companies and Western governments eager to make lucrative exploration deals.

But along with several former Soviet states, it bears a legacy of gross environmental mistreatment. Ukraine and Belarus share the tragedy of the Chernobyl nuclear power explosion, the Baltic states grapple with dirty rivers, Azerbaijan suffers from industrial and oil pollution, and Turkmenistan and Uzbekistan live with poisons from pesticides used to protect Soviet-era cotton fields. In all, money for cleanup is scarce; aid from rich nations has been inadequate to undo the damage.

Beginning in the 1960s, Kremlin planners decided that the Soviet Union must be self-sufficient in cotton. The decision doomed the Aral Sea.

Canals began to suck water from the Syr Darya and Amu Darya rivers, and therefore from the sea itself, for fields mostly in Uzbekistan and Turkmenistan. At the time, the Aral Sea was a lake smaller in size only than the Caspian Sea, Lake Superior and Lake Victoria. Over the years, the Aral's surface area shrank by half, its water volume by three-quarters. The blotted shoreline became a source of poisonous salts and pesticides blown by unforgiving steppe winds across villages and towns throughout the region. Water tables dropped, and poor farmers and city dwellers alike were forced to rely on either brackish wells or tank trucks from afar for drinking water.

Soviet engineers knew that massive irrigation to produce cotton in Uzbekistan and Turkmenistan eventually would deplete the sea. They even concocted a replenishment plan to divert water from Siberian rivers into it. Soviet President Mikhail Gorbachev dropped the project. In any case, now that Uzbekistan and Turkmenistan are independent states, what central planning created is in no danger of being undone by uncoordinated governments. The cotton countries need the crops for export. No one here thinks that the intricate and wasteful system of canals and reservoirs is ever going to be modernized or plugged up, even though about half of the diverted water evaporates or sinks into sand.

So the dike project is an effort filled with irony: a small, underfunded and perhaps vain engineering feat is meant to correct, in a small way, destruction wrought by a huge and careless irrigation scheme that altered the face of Central Asia. It may seem to outsiders a labor of meager consolation, but for residents who live on the desolate shores of the Little Sea the dike offers hope, a commodity as rare here as rainfall.

Camel herders, shepherds, rice farmers and former fishermen talk of microclimatic change they expect. "We have enough desert. We will get moisture. Anything will be better than it is now. Fill the Little Sea," said Teleo Kurmuza, a camel breeder in the delta.

The dike is the brainchild of Aleshbaye Avdigazeavich, mayor of Aralsk. He is a rangy shoe-factory-owner-turned-Moses who thinks that parting the seas will revive fishing and sea traffic at his doorstep. "We took a decision," he said in an unapologetic interview. "We can't save the whole Aral Sea. We can save the Little Sea, and at least revive our farming, our fishing and our lives.

"Lots of researchers say don't do this, don't do that," Avdigazeavich said. "Well, you don't need a lot of brains to see what ought to be done." He pulled out a pitcher of water, a tea cup and a platter. The pitcher was the river, the cup the Little Sea, and the platter the rest of the Aral.

"I can fill this cup easily. But if I let the water spill into the platter, the water there evaporates quickly. The cup empties. It's elementary. We must keep the cup full," he said.

His Aralsk was once a seaport. You could call it a dryport now. The sea receded 30 miles from the shore. A crumbling promenade and railings decorated with metal sailboats and gulls frame a dusty basin littered with corroded boats. An empty swimming pool and parched shower stalls stand empty of summertime frolickers.

Walking along the shore recently, retiree Salima Zhasekeneva recalled a stroll she took with her grandson in 1974, when she spied a mound of land that had emerged from the harbor floor. "The sea was leaving, and it never came back," she said. "When the sea was here, we used to have lots of rain. It was cool. Now, all summer, the grass dries out. As soon as the wind blows, the sand lifts in the air. We have dust whirlwinds. Only whirlwinds. The mayor's idea is good, if the dam holds."

Kazakh desperation to do something about the Aral Sea is understandable. Few countries are afflicted by worse ecological ills than Kazakhstan. Researchers blame exposure to agrochemical wastes from the Aral seabed for a high incidence of anemia, stillbirths, and eye and lung disease among its 16 million people. "This is a liquid Chernobyl," said Lydia Astanina, editor of Greenwomen, an ecological newsletter in Almaty, the Kazakh capital.

If the disaster on Kazakhstan's west-central frontier was not enough, the country's eastern region suffers from the painful aftereffects of Soviet nuclear tests. In the Semey region, once the epicenter of Soviet testing, a third of all children are born with birth defects. Cancer deaths increased sevenfold during the 1980s. Half the population suffers from immune system deficiencies.

In between these toxic bookends, Kazakhstan remains a kind of Russian shooting gallery. The Russian military launches missiles and other weapons from rented bases onto ranges that extend to the middle of the country. Discarded fuel and stages of missiles fired from Russia's Baikonur space launch center -- just to the east of the Aral Sea -- befoul the landscape all the way to the northeast border. Opposition members of parliament have campaigned to close all the Russian bases, but without success. Rental income from Russia brings Kazakhstan needed cash. And revenue from oil exploration near the Caspian Sea is still years away.

Actually finding the sea -- Big or Little -- is not easy. A trip from Aralsk to the dike constitutes a journey back in time. After driving south along a bumpy, two-lane paved road, you travel west on dirt surfaces that soon turn into trails of crushed bush and sand; brick houses give way to homes of mud and reed. Forlorn landmarks point the way -- two marooned fishing boats at the village of Bugun; the beachless cemetery at Kareshalan; dry irrigation ditches, hollow ponds and dunes at Karategan. Everyone laughs when you ask where the Aral Sea is. "Fifty kilometers that way," said an old, bearded man in Karategan as he flicked his cigarette toward the setting sun. "Or it might be farther, who knows?"

You must drive onto the Aral seabed to get to the dike. A couple of decades ago, your jeep would be underwater. Don't be fooled by the flat terrain: Holes full of sand the consistency of talcum powder devour the fattest tires. The driver adds to the drama by narrating the dangers: "If we get stuck here, we're finished. Even camels don't come around."

As the hours pile up and you think maybe the Aral Sea is a mirage, trucks suddenly appear on the horizon, then the dike itself, and, beyond, the cliffs of Kokara Island. Well, Kokara is not actually an island anymore. It fused long ago with the western shore of the sea. Recently, a low-lying isthmus joined it to the eastern shore.

The builders hope the dike will make the land bridge permanent, so that in high water years, no precious liquid will flow across the isthmus into the Big Sea. At first glance, the project looks successful. As you face Kokara, gentle waves from the Little Sea lap against the dam to the right. To the left, there is nothing but a few puddles and then sand and thistly bushes as far as the eye can see.

A few species of fish that disappeared from the Little Sea have made a comeback. Salt-resistant flounder imported from the Black Sea are the main source of edible fish caught these days.

But the Little Sea dike is built of sand, and at the heart of the old channel the wall is eroding and has shrunk from about 25 feet across to a scant 15. This year, the flow from the nearby Syr Darya delta is strong -- reports say that more water than usual was released from a reservoir in Kyrgyzstan that feeds into the river's upper reaches. The builders are racing to avoid a collapse. The dike stands about 10 feet above the Little Sea and already has given way on several occasions.

Funding is a problem. Mayor Avdigazeavich scavenged gasoline and equipment from local supplies. The central government provided $2.5 million. "I have donated boots from my factories for the workers," he said.

He recoils at reports that his sand dike, unbuttressed by either a clay core or rock surface, will inevitably leak. "The dam will hold!" he said, as if determination alone will guarantee victory.

About This Series

It's sometimes hard to believe that the former republics of the Soviet Union once formed a unified empire, so different are the 14 countries that broke from Moscow's rule and stretch from the Baltic Sea in northern Europe to the Islamic center of Asia. Yet, they share troubling times.

This is the last in a series of stories that has reported on the situation in a number of the former republics. It has looked at some of the issues they have in common, ranging from ethnic tensions to environmental problems to the struggle to build prosperous economies.