Chinese dam construction has placed the Mekong River and its tributaries at risk

where millions of families ply its waters for a living in five downstream countries,

a leading Australian academic has warned.

"The fact that negative changes are occurring is beyond dispute," Milton

Osborne wrote in a report prepared for the Lowy Institute for International Policy,

based in Sydney, Australia.

In the 49-page report he cautioned that any predictions of irreversible negative

developments would be alarmist.

But he said China's decision in the 1980s to massively expand hydropower production

for domestic and international sales was now leaving its mark and this was highlighted

by record-low fish catches in Cambodia.

By the end of March this year, the annual fish catch - based on data collected from

the Tonle Sap and the Lower Mekong Basin - was down 50 percent on the same period

a year ago amid unusually low rainfall. This followed a 15 percent fall on stocks

for 2002 and again in 2001.

The Mekong River Commission has reported that the river's levels in 2004 may be the

lowest for perhaps 20 years.

Lack of rain in the current season was not the only factor at work, according to

Osborne.

Completion in China of two dams - Manwan and Dachaoshan - and construction of another

two - Xiaowan and Jinghong - is already having a negative impact on river flows,

the report found.

Plans for a further four dams are on the drawing boards.

And river blasting to remove rapids and obstacles aimed at improving navigation in

the southern Chinese province of Yunnan was compounding the problems of downstream

life on the waterways.

In Vietnam, the Yali Falls Dam has already cost Cambodian families dearly with unannounced

water releases claiming 39 lives. It is one of six dams planned for the Se San River,

which feeds into the Mekong, and Osborne says it appears that work on the second

dam known as Se San III may have already begun.

"Changes that have occurred in the space of 20 years are of such an order that

no exaggeration is involved in stating that the river's future as a vital part of

the life of mainland Southeast Asia is, as put to me by one highly qualified observer,

now on a knife edge."

Chief concerns include:

* Silt rich in nutrients for crops not finding its way down stream;

* Unseasonal flooding caused by unscheduled discharge by dams;

* Destruction of fish and plant life caused by sudden change in water climate after

discharge;

* River clearance destroying natural habitats;

* Dams blocking seasonal migrating patterns for fish and wildlife.

While it was too early to predict that falls in the fish catch herald a definitive

collapse, if this were to happen "it would be an extremely serious development

that would have profound long term consequences".

Fishers have no alternative means to sustain themselves nor is there an alternative

source of protein. The Mekong River accounts for 70 percent of Cambodia's protein

intake, and Osborne estimated that water from China provided "perhaps 40 percent"

of the river's volume during the low season.

The current threats are being posed amid forecasts that Cambodia's population will

double over the next two decades.

Osborne said if the sharp fall in fish catches becomes an established pattern over

the coming years the government could be forced to cutback on fishing levels in the

Mekong River Basin, to prevent a total collapse.

"The government led by Hun Sen has had a less than glowing record as far as

acting to conserve Cambodia's natural assets," Osborne says. "Its poor

performance in relation to illegal logging is a case in point.

"What is in doubt here is the readiness of the Cambodian government to recognize

the seriousness of the potential problem."

That includes tackling Beijing, which is sensitive to criticism on the issue and

has flouted international provisions on the treatment of downstream countries in

water management.

"Thailand and Cambodia, are led by men who are committed to a close relationship

with China that makes criticism of its actions difficult or almost impossible,"

he said.

Neither Laos or Vietnam were in a position to exert pressure on the Chinese to change

their plans.

Osborne added that the Mekong River Commission (MRC) has stood out as a target for

continuing criticism for its supposed failure to take an active role in addressing

these criticisms but he said such attacks were misguided.

"While its critics might want to think otherwise, the MRC has no mandate to

act on its own in any fashion that has not been approved by the member countries,"

he said.

Those member countries include Cambodia, Thailand, Vietnam, Laos and Burma (Myanmar).

"The Mekong, one of the world's great rivers, for the first time in its history

faces major threats to its environmental health and so to its vital roles as an essential

contributor to agricultural production and as a bountiful source of fish."