Tsetsegee Munkhbayar spent his childhood herding yaks on the banks of the Onggi, one of Mongolia's largest rivers. About 60,000 people and one million head of livestock depended on the powerful waterway. But in the early 1990s the essential life source began shrinking, grew contaminated, and by 2001 water that had coursed through his village for centuries had vanished—leaving a rocky riverbed, thirsty herds, and devastated families.

The dramatic dry-up was the result of unregulated hydraulic mining that used high-pressure water systems to extract gold and other minerals. With more than half the nation's land granted to mining, the effects were rapid and enormous—1,500 rivers and creeks were cut off and 300 lakes were emptied. Desperate for drinking water, Munkhbayar's family and neighbors dug wells. But groundwater was so contaminated that dozens of local children suffered serious liver damage. Munkhbayar's son was taken ill, and his mother lost her life.

Plagued by disease and ever dwindling water supplies, Mongolia's nomads—almost half the population—were forced to abandon their traditional way of life and migrate hundreds of miles from native lands. Steppes turned to deserts. And an ecosystem with limited water to begin with was brought to the brink of environmental disaster.

Then something rare, almost unthinkable, happened: Munkhbayar spoke out. Highly unusual for an ordinary herdsman, he was elected chairman of his local citizens' council, and he brought water issues to the attention of government officials at the provincial and ultimately national level. "The law of nature holds us accountable for our land," he says. "If we desert our land, who will be accountable for its fate? Who will be left to stop the disastrous outcomes of irresponsible governmental policy? I could not leave those questions unanswered; I had to take action myself."

With unwavering passion, he inspired thousands of local villagers, held press conferences, organized town hall meetings, lobbied legislators, and led protest marches—mobilizing an unprecedented level of grassroots participation among citizens who previously felt they had no power to shape government policy.

The Onggi River Movement he co-founded convinced government officials to expand and enforce mining regulations, pass new legislation, establish citizen oversight for the entire mining process, and start environmental restoration work. As a result, 35 of the 37 mining operations in the Onggi River Basin stopped destructive operations, the worst offender shut down, and for the first time in years the river flows again. Munkhbayar went on to unite 11 river movements, creating the Mongolian Nature Protection Coalition, now one of the nation's most influential civic and environmental organizations.

"When I started our movement six years ago, politicians thought I was a crazy man from the countryside who spoke nonsense," Munkhbayar says. "Gold miners said I prevented national economic growth. And my fellow citizens doubted their ability to challenge government policy. Today, officials ask our opinions, gold mines accept their mistakes, and most people not only understand their responsibility as citizens but attribute the flowing Onggi River to our efforts."

Munkhbayar's energy has not ebbed. He currently lobbies for legislation prohibiting mining upstream of river basins and in forests, government restitution for losses caused by irresponsible policies, precipitation-generating equipment at key locations, a forestation project along 250 miles of the Onggi River, and environmentally focused school textbooks.

"The environment has no border lines," he says. We are a landlocked country, but our mountain streams flow into the Arctic and Pacific Oceans and are headwaters for many Central Asian rivers. It is our duty to humankind to stop careless environmental practices that endanger precious natural resources. Each of us can make a powerful difference."