The livelihoods of 30,000 people in Stung Treng province are threatened by a plan

to build a series of hydroelectric dams in the Laotian part of the Sekong River Basin,

upstream of where the Tonle Sekong enters Stung Treng. Tens of thousands of people

living in Laos would also be affected.

Along the Sekong River in Stung Treng province, adults and children catch fish and other aquatic animals to feed their families and to sell at the market. Fish is the single most important source of dietary protein for people living in the vicinity of the Sekong River.

In Cambodia, the effects would extend into the Sesan and Srepok rivers, the Sekong's

main tributaries, into the Mekong River, and as far away as the Tonle Sap Lake.

The inevitably disastrous impacts of these dams on Cambodians living along the Sekong

River are not the subject of mere conjecture. According to Kim Sangha, Coordinator

of the 3S Protection Network ('3S' being the Sekong, Sesan and Srepok rivers), "More

than 55,000 Cambodian people living along the Sesan River, the Sekong's largest tributary,

are already suffering from the severe impacts of hydroelectric projects on the Sesan

in Vietnam."

These social, environmental and economic impacts on communities living along the

Sesan River in Ratanakkiri and Stung Treng provinces, caused by the state-owned Electricity

of Vietnam's Yali Falls dam, are internationally infamous although largely ignored

by the governments of Cambodia and Vietnam. The impacts on Cambodia's Sekong River

caused by the proposed dams in Laos would be very similar to the impacts already

occurring along the Sesan River.

The Sekong River Basin within Laos covers an area of approximately 23,000 square

kilometres (km2). Nine large dams would be built on the Sekong and its major tributaries,

and other dams may be constructed on smaller tributaries. Another 4,100 km2 of the

Sekong basin is located in Cambodia, where the Sekong flows for 140 kilometres through

the districts of Stung Treng, Siem Pang and Sesan in Stung Treng province, before

entering the Mekong River.

According to a forthcoming report by a Cambodian NGO, the Culture and Environment

Preservation Association (CEPA), there are 31 villages and 28,376 people living very

close to or directly adjacent to the Sekong River in Stung Treng province. The majority

of people living along the Sekong River are of the Lao, Kavet, Lun, Kuy and Khmer

Khe ethnic groups. They depend on the Sekong's fisheries for their major source of

dietary protein and income, while other aquatic animals, plants, and dry-season cultivation

of vegetables along the river's banks are important for food security and local economies.

The Laotian government's program of dam-building in the Sekong basin is largely designed

to generate electricity for sale to Vietnam and Thailand. One dam has already been

built on a Sekong tributary: the 76-meter-high Houay Ho hydroelectric dam was completed

in 1997. It was the first large hydroelectric project to be built in the Sekong River

Basin.

Another dam on a Sekong tributary has recently been proposed. Although there are

few details about the project, the Kansai Electric Power Company of Japan has signed

a Memorandum of Understanding to build the Xekatam Hydroelectric Project. Kansai

is presently conducting a feasibility study for the project, and has already publicly

stated that it intends to complete construction of the 50-to-60 megawatt (MW) project

by 2011.

However, these two projects pale in comparison to the grandiose scale of the hydroelectric

dams proposed to be built throughout the Sekong River Basin in Laos.

On the Sekong mainstream, the Sekong 4 hydroelectric project would have a generating

capacity of 460MW. The Sekong 4 dam would cost US$600 million to build, be 170m high,

and would take at least 14 months to fill with water. In March 2006, the Region Oil

Company of Russia signed a memorandum of understanding (MoU) with the Government

of Laos to undertake an 18-month-long study of Sekong 4. However, only six months

later, Oley Kabardin, Managing Director of Region Oil Co, announced that "Following

the study, we have decided to construct three projects, Xekong 4, Xekong 5 and Nam

Kong 1, while we need to collect more data on Nam Kong 3." In 2004, a power

system development plan (PSDP) for Laos suggested that upstream of the Sekong 4,

the massive 250m-high Sekong 5 hydroelectric project would, according to Region Oil,

have a generation capacity of 400MW. According to the Lao Power System Development

Plan of 2004, it would take three years to fill the Sekong 5 dam's reservoir.

The Nam Kong River is a large tributary of the Sekong, and Region Oil Co is proposing

to build two hydroelectric dams on this river. The Nam Kong 1 project would have

a generation capacity of approximately 240MW and a 32m dam. The probable cost of

the project is US$200 million. The 35MW Nam Kong 3 would be upstream of the Nam Kong

1.

According to Region Oil Co, construction of these three projects would begin in 2007,

with the Sekong 4 expected to be completed by 2012, Sekong 5 in 2014, and the Nam

Kong 1 in 2013.

The Xekaman River is the major tributary of the Sekong. Three hydroelectric dams

are proposed: the Xekaman 1, Xekaman 3 and Xekaman 4. In March 2006, Viet-Lao Power

Investment and Development Joint-Stock Company began a study of Xekaman 1, a 465MW,

128m dam that would cost US$535 million. The Xekaman 1 reservoir would flood an area

of more than 200km2 and take three years to fill. Viet-Lao Power has not yet studied

the proposed 55MW Xekaman 4. Construction of the US$273 million Xekaman 3 project

began in April 2006. This 250MW project includes a 128 m dam located in the upper

Xekaman basin, and is the single largest investment ever made by Vietnam in Laos.

The Xepian-Xenamnoi project would consist of two large dams. A 35m-high dam would

divert most of the Xenamnoi River into the reservoir of an 85m-high dam on the Xepian

River, a large tributary entering the Sekong just upstream of the Lao-Cambodian border.

In August 2006, a Memorandum of Understanding was signed between the Government of

Laos and two South Korean companies, SK Engineering and Construction Company and

Western Power Company, to undertake a feasibility study of this proposed 400MW dam.

As each of the dams in the Sekong basin in Laos are built, the impacts on Cambodia

will steadily accumulate. Experience from the Sesan River indicates the type and

severity of the impacts that will occur in the Sekong and the communities living

along it.

First, most of the Sekong dams are designed as large storage dams. In other words,

during the rainy season, the dams will generate electricity but also capture and

store large amounts of water that would otherwise flow through the Sekong. During

the dry season, when water levels in the river are naturally low, huge amounts of

water would be released from the reservoirs to generate electricity and then enter

the river.

From this relatively simple exercise in hydroelectric engineering, some interrelated

impacts follow:

•When water is stored in the reservoir, the submerged vegetation and organic matter

begins to rot. This process of decay consumes much of the oxygen in the water, and

also makes the water putrid. When this water is released through the dam into a river,

it is largely deoxygenated and often poisonous to aquatic life. Toxic blue-green

algae caused by dams are also a serious threat to aquatic life, domestic livestock,

wildlife and humans. Large-scale fish kills have been documented downstream of dams

as a result of the release of reservoir water. Along the Sesan River, the fisheries

declined precipitously following the release of water from the Yali Falls reservoir.

Depending on the amount of vegetation flooded by a reservoir, releases of deoxygenated,

rancid water into the river downstream of the dam can last for many years, and sometimes

for decades. The reservoir areas of all of the proposed dams in the Sekong basin

are densely vegetated, and long-term releases of very poor quality water from these

reservoirs and into Cambodia's Sekong River are a certainty.

•Water released from the reservoirs is often unfit for human consumption and use.

In all of the communities living along the Sekong River, people depend on the river

as a source of water for drinking and cooking. The river is also used for doing laundry

and for bathing. Children often swim and play in the river for hours a day, and it

is children who are particularly susceptible to the health impacts of exposure to

this water. People's livestock, including pigs, chickens, cattle and water buffalo

also depend on the river for drinking water.

•As a river's water flows into a reservoir, the silt and sediment being carried by

the water are deposited in the reservoir. When this sediment-free water is released

into the river downstream of the dam, it is known as "hungry water" because

it eats away the riverbanks to replenish its sediment load. Extensive erosion of

riverbanks along the Sekong River will deprive local people of the riverbank gardens

that they cultivate during the dry season. Houses, other buildings, trees and other

vegetation will collapse into the river as the water erodes away the riverbank.

•This erosion is exacerbated by the daily surges in water levels and volumes caused

by water released through the dam to generate electricity. All of the Sekong dams

are designed to supply electricity demand in Vietnam and Thailand, and all of these

dams will be supply "peak" electricity. In other words, when daily demand

for electricity in Vietnam and Thailand is highest, usually early in the morning

and in the late afternoon and evening, the Sekong dams will release water. At other

times of the day and during the night, they will stop generating electricity and

will not be releasing water. Along the Sekong in Cambodia, water levels will fluctuate

from very low levels during the night to higher levels during the day as surges of

water are released from the dams.

These fluctuations in water levels will be particularly evident during the dry season.

It is certain that these high water levels and the releases of poor quality "hungry

water" and resultant erosion will cause severe damage to the aquatic habitat

and ecosystems of the Sekong River. Critical habitat such as wetland forests and

rapids, which are naturally exposed during the dry season, will become submerged

and eventually be destroyed. Deep pools, which serve as a dry season refuge for most

of the fish species living in the river during the dry season, will become filled

with silt eroded from the riverbanks. River birds, monitor lizards, soft-shelled

turtles and other riparian wildlife are also dependent on the river's waters.

Local people living along the Sekong report that they do most of their fishing during

the dry season, and that their most important fishing grounds are in the vicinity

of rapids and in deep pools. The destruction of the rapids and deep pools will have

long-term and irreversible impacts on the fisheries of the Sekong, and on the food

security of local people.

One of the widespread observations of Cambodians living along the Sesan River is

that the "river isn't like it used to be" and that the "river doesn't

flow naturally" as a result of the Yali Falls dam in Vietnam. The water storage

and operation of a large hydroelectric dam radically alters the natural flow of a

river. The dams in the Sekong basin will significantly increase water volume and

flows in the Sekong River during the dry season, and noticeably reduce volume and

flow during the early part of the rainy season, when the reservoirs of the dams are

at their lowest and can begin to store water again. This alteration of the Sekong's

natural flow will very likely have impacts on the seasonal feeding and reproductive

migrations for fish in the Sekong and between it and the Mekong River, delaying or

even preventing these migrations and having a direct impact on the productivity of

the Sekong fisheries.

As these inter-related impacts accumulate, the Sekong River, its fisheries and aquatic

life, and the food security and economies of the communities living along the river

will be devastated.

Furthermore, there is clear evidence linking fish in the Sekong, Sesan and Srepok

rivers in Laos and Cambodia and the Mekong River in Cambodia, Laos and Thailand.

In a peer-reviewed journal article published in the Natural History Bulletin of the

Siam Society in Thailand in 2003, scientists have clearly linked important fish migrations

from the Tonle Sap Lake in Cambodia with the Mekong, Sekong, Sesan and Srepok rivers

in Laos and Cambodia. Another article published in Asian Fisheries Science in 2004

has shown that other important fish species migrate annually between the Sekong,

Sesan and Srepok rivers and the Mekong River in Cambodia and southern Laos, travelling

the Mekong River as far as northeast Thailand. Therefore, dam-inflicted effects on

fish populations in the Sekong River Basin in Laos and Cambodia can be expected to

have serious negative consequences for fish and fisheries throughout much of the

lower Mekong River Basin.

Cambodia and Laos are signatories to the "Agreement on the Cooperation for the

Sustainable Development of the Mekong River Basin," generally known as the Mekong

Agreement. Article 7 of the Agreement requires that states "make every effort

to avoid, minimize and mitigate harmful effects that might occur to the environment,

especially the water quantity and quality, the aquatic (eco-system) conditions, and

ecological balance of the river system."

"It is clear that there will be harmful effects on the environment, water quantity

and quality, aquatic and ecosystem conditions, and the ecological balance of Cambodia's

Sekong River if any of these dams are built in the Sekong basin in Laos," says

Tep Bunnarith of CEPA. It is also clear that so far the Government of Laos has not

made any effort to avoid or minimise these effects, as it continues to approve and

participate in the planning and construction of these dams. As experience along the

Sesan River, and throughout the Mekong River Basin indicates, once these dams become

operational and the impacts occur, governments and investors have no interest in

mitigating impacts.

"The Government of Cambodia has recourse through the Mekong River Commission

to make known its concerns about the likely impacts of the Sekong dams to the Government

of Laos," Bunnarith says. "At the very least, Cambodia should demand that

an independent, cumulative environmental and social impact assessment of the Sekong

basin dams and the Sekong, Mekong, Sesan and Srepok rivers should be undertaken before

construction of any of these dams commences. Communities living along the Sekong

River in Stung Treng province should be fully informed of these impacts and should

have the opportunity to voice their concerns to their government and the Government

of Laos. But in the end, it can only be hoped that the Government of Laos will realise

that being a good neighbor means not inflicting harm on Cambodians."

* Dave Hubbel is a researcher who has been working in the Mekong Region for the past

15 years.