A villager drinks eagerly during the drought in 2003, Hengnan county, Hunan province. Luo Xinguo

When Ma Jun stood on the banks of the mighty Yangtze River in 1994, he had little inkling of his future calling - saving China's rivers.

Named one of Time magazine's 100 Most Influential Persons of 2006, Ma often recalls the good old days of his childhood spent by the Jin'gouhe River, a major source of water for Beijing residents.

"The water glistened with swarms of fish," he says. It was where Ma learned to swim.

By the late 1970s, the start of reform and opening up, the Jin'gouhe River had started to smell foul, says Ma. Its water quality was rated Category V - not fit for drinking.

"Many rivers in Beijing have become mere outlets for waste water discharge by factories or households. Some of them have simply dried up."

By the time Ma graduated in 1993 and began work as a journalist, he felt deeply distressed by what was happening around the Yangtze River, the lifeline of South China.

"What I saw was rampant deforestation, soil erosion and damage to the environment."

Nationwide, nearly all of China's rivers and lakes were polluted. Dongting Lake, for example, once the country's largest freshwater lake, had dwindled in both volume and area. The Fenhe River in Northwest China's Shanxi province even became a threat to the local population owing to heavy industrial pollution.

Faced with water shortages, China looked at several options and zeroed in on the construction of reservoirs and large dams in southwestern China and projects to divert rivers from the south to the north.

Ma, however, questioned their feasibility, as these measures failed to take into account ecological concerns.

He turned his observations into a book, China's Water Crisis, which has been compared to Rachel Carson's Silent Spring, published in 1962 and widely credited with launching the environmental movement. Ma's book published in 1999 was the first major work to put China's environmental crisis under the microscope.

"If policy makers do not approach water treatment from the point of view of environmental protection and sustainable development, many regions in China will face a water crisis in the near future," he wrote.

More than 60 percent of China's fresh water is contaminated and more than half of its major cities do not meet the country's modest air quality standards.

Ma was not content with just pointing out the problems. He started thinking about what he could do, and this resolve strengthened during his stint with an international environmental consulting company and tenure as a visiting scholar at Yale University for a year.