Will the Project have destructive effects on fisheries on the Nakai plateau or in the downstream Xe Bang Fai basin? Are there endemic species of fish that are threatened?

The following independent studies have served as the basis to conclude on the Project effect on fisheries in the Nam Theun and Xe Bang Fai rivers:

- Aquatic biology in Xe Bang Hian and some rivers in northern Laos (Kottelat, June 1997)

- Potential Impacts of Nam Theun 2 Hydropower Project on the Fish and Aquatic Fauna of the Nam Theun & Xe Bang Fai Basins, Lao PDR, Main Report, Kottelat (1996)

- Potential Impacts of Nam Theun 2 Hydropower Project on the Fish and Aquatic Fauna of the Nam Theun & Xe Bang Fai Basins, Lao PDR, Annex, Kottelat

- Potential Impacts of Nam Theun 2 Hydropower Project on the Fish and Aquatic Fauna of the Nam Theun & Xe Bang Fai Basins, Lao PDR, Executive Summary – Lao Language, Kottelat (1996)

- Distribution of Fishes Previously Considered Endemic to the Nam Theun & Xe Bang Fai Basins, Lao PDR, Kottelat (1997)

Dr. Kottelat’s reports indicate that all but 3 of the 17 fish species formally recorded in his 1996 study as endemic to the Xe Bang Fai and Nam Theun systems are in fact also found in other parts of Laos. Of these three species, two presently exist in the tributaries feeding the Nam Theun and may very well relocate further upstream in those same tributaries. The third species is located immediately downstream of the proposed dam site location in a waterfall that exists there and will be significantly impacted by the reduction in riparian flows. NTEC believes that it is highly probable that this species will also be found in other parts of Laos and is continuing to study this matter.

As far as biodiversity is concerned, the Project will cause some reduction in the numbers of species in the affected zones. This will be more evident than elsewhere in the reservoir and the Nam Theun reach from the Dam to the Nam Phao confluence (EAMP section 6.2). In the reservoir there will be a shift in balance of species away from those dependent on fast running flows towards those flourishing in quieter waters. In the downstream reach of the Nam Theun there will be a shift towards more sedentary species than presently exist. Little changes in species are expected in the Gnommalat Plain and Xe Bang Fai areas.

As far as quantity is concerned, more water area usually equals more fish. In addition, the breakdown of trees and shrubs left in the reservoir will act as a primary source of food for fish. As an example the present annual fish catch in the area to be part of the reservoir has been estimated by CARE as 104 tonnes. The EAMP estimates an annual sustainable catch of 765 tonnes. SMEC estimated a sustainable catch of about 1,000 tonnes. The fact that the Reservoir will be an upland lake rather than a low level one, like Nam Ngum, may however tend to make it less productive than Nam Ngum’s officially recorded figures of about 850 tonnes/year. Fishing in the reservoir will become an important source of revenue for the local population. Accordingly, the EAMP recommends the clear felling of navigation lanes and fishing zones prior to inundation to make fishing in the reservoir easier and to minimize “ghost-netting”.

The downstream channel, the Nam Phit and perhaps the Nam Gnom will have slightly increased fish production because of the increase in total water. The section of the Nam Theun between the Dam and its confluence with the Nam Phao will probably have a decrease in fish production because of the over 80% reduction in annual flow in this reach. However, there is some possibility, considering the very low existing population in this area, that the increased nutrient levels may actually increase production.

No people live in this reach though intermittent fishing is evident. The large increase in fish tonnages in the reservoir itself should give any of these people a close alternative option. The Social Development Plan (SDP) considers the compensation necessary for any residual human impacts in this area.

The increase river flow in the Xe Bang Fai River should have a positive effect on fisheries in the river. In the case of a diminution of catches (possible during the first years following operation), the population will be compensated for the losses.

In conclusion, there will be a larger tonnage of fish but of fewer types as a result of the Project.

What is the predicted water quality for the reservoir ? Will the reservoir become uneconomic because of sediment from erosion ?

The following independent studies have served as the basis to conclude on the sediment and water quality in the reservoir:

- Predictions of the Water quality characteristics of the proposed Nam Theun Reservoir System (Centre for Water Research, University of Western Australia, April 1997, updated in September 2000).
- Report on Residual Biomass in Reservoir (J.R. Prosser, February 1997)
- Anticipated Response of Terrestrial Plants to Inundation in the area of the Nam Theun 2 Reservoir, Francois Obein, January 2001

The Prosser report looked at the likely extent of organic material remaining in the reservoir area at the time of filling on the basis of the presently known situation and predicted logging extraction rates. About half of the inundation has already been illegally logged and the predicted residual biomass of between 57 and 70 tons/hectare is quite low by tropical lake standards. This low level will contribute towards good water quality in the reservoir from first filling.

The report prepared by the Centre for Water Research addresses Water Quality issue in the Reservoir and the downstream discharges from it. Extremely advanced computer techniques were used in this study, which included the affects of buried organic material measured throughout the reservoir site. The report predicts many water quality indicators, such as:

- Dissolved Oxygen
- Ammonia
- Phosphorous
- Temperature
- Sediment
- Circulation patterns

The report predicts water of high quality in the reservoir and its downstream discharges from the time of first filling.

Presently the inflow waters are of the highest quality. If they were to remain as clean in the future it would take over 1,800 years for the Nam Theun 2 reservoir to fill with sediment. However, the EAMP and the Water Quality Study have considered what might happen if the erosion rates increased by 25 times as much as the current rate. This has happened in New Zealand when areas have been converted to logging production. For this case 325 million cubic meters of sediment would enter the lake in its first 50 years of operation. As the Dead Storage Zone of the Reservoir has a minimum volume of 380 million cubic meters, even this high rate of sedimentation would have no significant effect on the economics of the Project - even if, as is probable, part of this sediment stayed in the upper active storage zone.

However, the developers also looked at extremely bad cases of sedimentation around the world. For instance, if major logging occurred in the catchment and there were very poor management practices in road construction and little regrowth of ground cover, 920 million cubic meters of sediment could enter the lake in its first 50 years of operation, over 70 times the present rate. Developers also considered the possibility of much of this volume of sediment staying high up in the Active Storage Zone, thus reducing the volume of water storable to make electricity. At these very high levels of erosion there is a small but measurable reduction in available energy for sale, by the end of 50 years, of about 11% per year. The reduction after 25 years is about 6.6%.

While such a reduction does not make the Project uneconomic, it does make it less profitable. The bigger losses would occur in the later period when the Project will be totally owned by the GOL. It is obviously in everybody’s interest to ensure this does not happen. Effective management of the Nakai – Nam Theun NBCA can achieve this.

The project implementation will actually trigger the protection of more than 4,000 km2 of forested mountains (the Nam Theun 2 Watershed and NBCA) overhanging the eastern and northeastern borders of the reservoir, in that it will initiate the release of funding and supervision of a carefully developed conservation plan. Without the Project – and thus the funding it allows – these forests will most likely continue to degrade. There are no other projects effectively protecting the forests of Laos in such a large scale, let alone the Nam Theun area.

Protected Area managers worldwide desperately seek funding, and one of the most sustainable approaches is considered to be “user pays” arrangement. In the Nam Theun 2 case, not only will the Nam Theun 2 Power Company (NTPC) pay for protection of the water source (i.e. the project watershed), but it will also pay for protection of the biodiversity in the watershed and that of the surrounding (non-watershed).

How will Nam Theun 2 impact on the nearby Protected Area (NBCA) and watershed ? Will the Nakai Reservoir flood part of the Nakai-Nam Theun NBCA ?

When created in 1993, the Nakai-Nam Theun National Biodiversity Conservation Area (NNT NBCA) was defined as covering 3,554 km2, with the Nam Theun River representing its western border on the Nakai plateau. The advent of the reservoir will slightly reduce its size to 3,420 km2. However, this reduction in size of the original NNT NBCA has now been largely compensated by the acceptance from the GOL to endorse two major corridors linking the NNT NBCA to the Hin Nam Nor and Phou Hin Poun NBCAs, which size are respectively 653 km2 and 33 km2. Such approvals by the GOL now bring the total size of the NNT NBCA and corridors to 4,106 km2.

In total, there will be about 463 km2 of land changed for creating the reservoir, constructing roads, resettlement villages and other uses. Of this 463 km2, about 243 km2 are already located either in logged areas or used for agriculture (ref. EAMP 6.6.2.1). The remaining 220 km2 previously covered with forest will represent a net loss is 6.5 % of forested area from the watershed (ref. EAMP 6.6.2.1).

As a trade off, the entire watershed area and NNT NBCA and corridors, together with the reservoir area, i.e. a total of 4,550 km2 of which more than 4,000 km2 of forest recognized to be of great significance in term of biodiversity, will be placed under the jurisdiction of the Watershed Management Protection Authority (WMPA). WMPA is a special purpose Government entity authority established especially to manage these wild areas together with the indigenous residents. WMPA will be funded by the Project with more than US$ 30 million disbursed over 30 years, of which US$ 6.5 million during the construction period and US$ 1 million per year during the 25 year of operation.

What is the current situation in term of animal species found on the Nakai Plateau ? What are the ones that will be most affected by the Project ?

Because of the current human pressures on the Plateau, all of the species found on the Nakai Plateau and in the watershed, such as elephants, white winged ducks and various species of birds, are currently under threat. The opportunities the Project will give to improve resettlers’ livelihoods and the proper protection of the NBCA should halt this trend and provide a net environmental benefit. Chapter 6 of the EAMP, indicate globally threatened species in the area. All of these globally threatened species are primarily based in the NBCA except for the white winged duck which uses some of the riverine habitats to be inundated, and the elephant which uses Savannah woodland, some of which will be lost. These two species are presently probably not genetically or demographically secure because of their very small populations, 5 to 10 pair of white winged ducks and 100 to 150 elephants. The EAMP recommends the following mitigation/compensation measures related to animal species found on the Plateau:

- Basic line monitoring for wildlife system dynamic analysis
- Management of 16 key bird and animal species on plateau
- Management of white winged duck
- Management of elephant
- Public education on environmental issues
- Enforcement of hunting controls

It is probable that the white winged duck may establish itself in the new riverine habitats to be formed by the reservoir or in existing habitats within 60 km of the site. However, the EAMP recommends further study of other sites, generally also containing populations at risk, and out-breeding to those locations.

The elephant population presently consists of two herds near the Nam Xot and Nam Theun entries to the Plateau. The southern herd will be largely unaffected by the Project except as far as genetic interchange with the northern herd is affected. The northern herd is affected. The northern herd is believed to presently migrate across the river to the Nam Malou area in the Dry Season and even further to link with the Khammouane limestone meta-population. This route will be closed off by the reservoir, leaving the only accesses via the Dam itself and over the bridge to be constructed at Ban Thalang to carry route 8B. There is international experience in training elephants to use new routes such as this, combined with food trails. NTEC has offered to support studies to consider this issue in detail and particularly measures to assist resolving the human/elephant problems of crop destruction, which are already evident on the Plateau. NTEC has advised GOL that it is prepared to assist in studies to help train elephants to new routes and other measures.

So far as fish are concerned, there may be a change in balance on the Plateau towards species flourishing in quieter waters. Species related to rapids type environments may relocate to tributary streams but this cannot be assured. In 1996, a fish survey by Maurice Kottelat located 11 species on the Plateau and 6 species in the Xe Bang Fai, not previously known to the scientific world. In 1997 in a four-week field trip Kottelat examined various rivers in the north of Laos and found 14 of these 17 species in other locations. It seems probable that further search would find all the remaining species previously unrecorded. The EAMP recommends the following mitigation/compensation measures related to aquatic biodiversity:

- Minimum guaranteed release to Nam Theun
- Compliance with water-quality standards
- Monitoring water quality

Ultimately, the reservoir will develop many new habitats, and some wild species may flourish.