PHNOM PENH Each morning of his workday during the rainy season from mid-June to mid-October this year, Thanongdeth Insisiengmay was able to click open an e-mail in his
desktop computer to find water level and rainfall readings on the Mekong River that were sent from China.

Thanongdeth is a hydrologist who works for the Mekong River Commission. The commission was established by the governments of Cambodia, Laos, Thailand and
Vietnam in 1995 – at the end of a long period of conflict in the region to help manage the river that flows for 4,880 kilometers (3,000 miles) through or between no fewer than six Asian countries. While the commission can do some useful things with its present membership, critics say that it cannot hope to ensure that the rich resources of the Mekong are developed in the most rational and sustainable way unless the two other states along the Mekong, China and Burma, join the organization and cooperate fully in its activities.

“Cooperation between the upstream and downstream countries is vital,” said Sin Niny, the Cambodian official who currently chairs the commission’s joint committee. “We would like to avoid confrontation in the region.” Development issues and plans will be discussed when
leaders of all six riparian countries meet for the first time Sunday in Phnom Penh, ahead of a summit meeting of East Asian countries next week.

With international conflicts over river water becoming more frequent, there is concern that the Mekong could become a serious source of tension unless the six states can agree on rules for developing the river. That is why China’s agreement in April to send the readings from two monitoring stations on its section of the Mekong, more than 1,000 kilometers upstream from Phnom Penh, is seen as a small but significant improvement in managing one of Asia’s biggest and least polluted rivers.

The commission plans to feed the Chinese information into an improved flood-forecasting system it is developing – a vital service for Cambodia and the three other countries of the lower Mekong basin, where floods caused the deaths of 1,100 people and $500 million in
damage in 2000 and 2001. “This will make a very big difference in our flood warnings,” Thanongdeth said. “They will be more accurate and almost instantaneous.”

Unlike nearly all other major rivers in Asia, the Mekong has few big cities on its banks and not much industry to contribute to pollution. But that will change over the next 30 years. The number of people living near the river and its many tributaries is expected to rise to
more that 100 million, from around 70 million today. Urbanization and industrialization will intensify. And the pressure on the basin’s natural resources – chiefly forests, fisheries and agriculture – will grow.

Scientists estimate that about 1,700 species of fish live in the waters of the Mekong, which supports one of the biggest inland fisheries in the world. The total annual catch of the four downstream countries – Cambodia, Laos, Thailand and Vietnam – is estimated to be at least 1.6 million metric tons, worth $1.4 billion.The fish provide a key source of protein for local people.

“Relations between countries in the region have never been more positive,” said the commission’s chief executive officer, Joern Kristensen. “We must now ensure that the Mekong basin can sustain the growing population by finding the right balance between development and conservation.” Already, there are concerns that rampant logging, much
of it illegal, soil erosion and overfishing are threatening the health of the Mekong.

Initiated a decade ago, the Greater Mekong Subregion program that will be the focus of the summit conference in Phnom Penh encompasses a broader area than just the Mekong basin but will clearly have a heavy impact on the river. Overall investment in the program so far amounts to about $2 billion. Backed by the Asian Development Bank, China and
Japan, among others, the program aims to reduce poverty and promote greater prosperity by improving road, rail, telecommunications and power links among the five Southeast Asian members and between them and China’s Yunnan Province. The Mekong, which the Chinese call the Lancang, runs through southwestern China for more than one-third of its
length.

In a preparatory meeting for the summit conference, Myong-Ho Shin, vice president of the Asian Development Bank, warned the six countries not to pursue prosperity at the expense of the environment. “There is no room for complacency,” he said. “In many respects, the most challenging task is joint initiatives to manage common natural
resources and to protect the environment.”

Yet in the race to harness the benefits of the Mekong, some countries are pressing ahead with extensive building of dams on their sections of the river or its tributaries without adequate consultations or environmental impact studies, despite the concerns of downstream communities that fear they will be adversely affected. In January,
China began construction of a third hydroelectric power dam on the Mekong that will be second in size only to the mammoth Three Gorges Dam on the Yangtze River. Two Chinese hydropower plants are already in operation on the Mekong and five more are planned by 2020. They will provide electricity not only to Yunnan, one of China’s poorest and
least developed provinces, but also to densely populated and industrialized zones on the east coast of China, including greater Shanghai and Guangdong, that need power. Chinese officials assert that the Mekong dams will benefit downstream countries, by storing water in the rainy season to reduce flooding and releasing it when needed in the dry season. Only about 16 percent of the water that flows through the Mekong River each year comes from China. But the Chinese contribution becomes increasingly important in the dry season from November to May when the river relies for water on the melting of glaciers high in the
Tibetan plateau.

The downstream countries have their own projects or plans to build hydropower dams. But some scientists and Southeast Asian officials worry that the Chinese dams will decrease the water flow in the Mekong as well as the fisheries.

Despite such concerns, Vietnam started construction in June of a second big dam on the Sesan River, which runs through its territory and northeastern Cambodia into the Mekong. Hanoi says four more dams for generating electricity are planned on its section of the Sesan. Vietnam’s move surprised and irritated Cambodian officials who were holding talks with counterparts in Hanoi on the conduct of a joint study of the environmental impact of the new dam.

Vietnam has asserted that China’s dams on the Mekong, by cutting the flow of river water, are causing increasing intrusion of salt water into the Mekong Delta, where the river flows into the South China Sea.

The delta produces about half Vietnam’s agricultural output.

Still, Kristensen, the commission’s chief executive, said that all six countries with direct interests in the future of the Mekong River were showing greater readiness to make concessions for the common good. “I think that we have a much better foundation for cooperation and sustainable development than we had a few years ago,” he said.