Irrigation
The present use of water for irrigation is mainly in the Delta, where the flow is fully utilized to (1) curb salinity intrusion and (2) for irrigation. While in north east Thailand the tributaries are fully exploited, there is a large potential for the expansion and intensification of irrigated agriculture in Cambodia, and in the Vientiane Plain in Laos. Hydropower dams in China and on tributaries may augment dry season flows by around 50%, but the demand is projected to double or triple throughout the Lower Basin.

Water Supply
Around 85% of the total water supply in the Mekong River Basin is to agriculture. Water supplies for domestic and industrial use account approximately equally for the remaining 15%. The total demand is less than 10% of the annual river flow of 475,000Mm³, but this neglects the annual distribution of flow, the demand of salinity control, and the impact on the environment including Tonle Sap.

In China and Thailand, around 80% of households have water supply, and around 30% in the remainder of the basin. Demands are expected to grow around 30% for irrigation, 50% for domestic supply and 100% for industrial supply over the next ten years.

Hydropower
The two major dams in the basin at present are Manwan in China and Nam Ngum in Laos. Construction is underway on reservoirs with a storage capacity of 15,500 Mm³ in China. A nine fold increase in the installed capacity is planned over the next ten years (with an ultimate 18 fold increase). Of the total increase to 2010, 35 % will be in the upstream basin, China and Myanmar (against 52 % ultimately). The dam construction will have major social and environmental consequences, displacing large numbers of mainly ethnic minorities, the loss of valuable farmland and the destruction of forests and aquatic ecosystems.

In 1970, an Indicative Basin Plan for the Lower Mekong was prepared by the Mekong Committee (the present Mekong River Commission). The plan proposed a total installed capacity of 17,400 MW with a storage capacity of 140,000 Mm³, 30 % of the average annual flow. The largest single scheme was Pa Mong Dam on the Thai-Lao border, with a capacity of 4,800MW and storage of 75,000 Mm³. The reservoir would have provided a dry season flow of 2,000 m3/s and flood control, but required the relocation of 250,000 people. The Pa Mong scheme was dropped owing to uncertainty over the impact on Tonle Sap and the Delta, the huge resettlement required and general environmental concerns.

Mainstream reservoirs are now replaced in the plans by run-of-river hydropower schemes, which have lower environmental impacts, but still form a barrier to migrating fish. Nonetheless, with cooperation on mainstream projects becoming drawn out, the planning emphasis has shifted to tributary development, within the individual riparian states.

Fisheries
The present fisheries yield of the Basin is nearly one million ton per year. 8-10 percent comes from aquaculture, and the rest from freshwater capture.

Fish is an important part of the staple diet, to which it supplies most of the protein - over 80 percent in Cambodia, for instance. Tonle Sap is among the World's most productive freshwater fisheries areas.

FAO statistics indicate a steady yield in all four member countries in the period 1988-93. The capture stock is utilised close to its capacity. The aquaculture production is escalating rapidly in Cambodia and in the Delta.

Today, the capture fisheries is exposed to habitat degradation, and barriers to migration, while aquaculture production is exposed to a deteriorating water quality, partly due to polluted irrigation tailwater.

Within its Fisheries Programme, The Mekong River Commission has produced a strategy and an outline of a programme for integrated fisheries management and development, covering both capture fisheries and aquaculture. The strategy emphasises the basinwide need and benefits of structural, institutional, and human resource development efforts.

Navigation and transport
Waterways are an alternative or supplement to the ongoing expansion of the road network by provision or upgrading of the 'waterways feeder network'. Besides this, waterborne transport will facilitate or even guarantee access to places that are not or not easily reached by road.

Tourism and recreation
From one country to another, this sector is either the largest or a major foreign currency earner, with an attractive potential for further development, which can be pursued in a basinwide collaboration.

Interbasin Diversion
There are presently no significant interbasin diversions. The major planned diversion is from the tributary Kok River in northern Thailand to the Chao Phraya River, augmenting the water supply to Bangkok via Sirikit Reservoir. The diversion would take place in the wet season only, a maximum of 140 m³/s and 2.8 % of the average Mekong River wet season flow at Chiang Saen (near the Kok-Mekong confluence). That this scheme (and others) have not been implemented as yet is a reflection on the major capital investment required, the impact on the environment, the social implications and the large scope for water demand management.

Environment
The development incurs a stress on the environment:

• Population pressure (by growth and migration)
• Increased per capita consumption of energy, food and water
• Deforestation, shifting cultivation, forest encroachment
• The adverse environmental impacts of large reservoirs: resettlement of minority people, loss of forest and aquatic ecosystem, and erosion of the river downstream
• The adverse impacts of land degradation and structural interventions on fisheries (spawning and migration) 
• Soil salinity increasing through improper use of irrigation water
• High water demands of dry season rice cultivation (including an escalating withdrawal for small-scale pump irrigation)
• Agrochemical contamination of edible fish
• The sensitivity of Tonle Sap and the Delta to changes in the hydrological and morphological regime
• Salinity intrusion and acid-sulphate soils in the Delta

Watershed Management
The forest, wetland, and coastal ecosystems, are continuously being degraded and impoverished in the Lower Mekong Basin, due to a multitude of reasons.

Cambodia still probably has the most diversified and preserved forest/wetland ecosystems in the Basin. The forests are threatened by logging. The Tonle Sap River with its Great Lake represent the largest freshwater ecosystem in the region with, among others, a diversified stock of riverine fishery, now threatened by increased siltation rates.

Lao PDR is one of the richest countries in the region in terms of bio-diversity, rather due to a large relatively intact area of forest resources than taxonomic diversity. Many areas are under serious threat due to hydropower development schemes, logging, wildlife trade, local fuel wood and charcoal production, etc.

In contrast, bio-diversity degradation in Thailand has already proceeded to a stage where only limited areas of species richness exist within the Lower Mekong Basin. The country is now a net purchaser of ecosystem services and goods from neighbouring countries with relatively more plentiful forest resources.

The Mekong Delta in Vietnam is fully affected by human impacts (conversion of mangrove forests to shrimp farms and wet rice cultivation, drainage works, etc.). The transboundary ecosystem, Plain of Reeds, between Cambodia and Vietnam is an important seasonally flooded area with a rich flora and fauna composition.

The transboundary effects of escalating asymmetry between riparian countries in forest ecosystem functions have been poorly addressed in basin-wide policies.