State of water environmental issues
Lao PDR has rich water resources, mainly good quality fresh water. Water is an essential part of the life and culture of Lao people, and also contributes to the socio-economic development goals of the country. Ultimately the welfare of Lao PDR is bound up with water and all development plans will depend on water resources in some way. The contribution of the water sector has been examined through water sub-sectors: Irrigation, Hydro-power, Navigation, Fisheries, Urban Water Supply, and Rural Water Supply which are major users and the amount of water uses by these sub-sectors are being significantly increased.
The total of annual water flow in Lao PDR is estimated at 270 billion cubic meters, equivalent to 35% of the average annual flow of the whole Mekong Basin. The monthly distribution of the flow of the rivers in Lao PDR closely follows the pattern of rainfall: about 80% during the rainy season (May-October) and 20% in the dry season, from November to April. For some rivers in the central and southern parts of the country (particularly Se Bang Fai, Se Bang Hieng and Se Done) the flow in the dry season is less: around 10 to 15% of the annual flow. The rivers outside the Mekong Basin flow through Viet Nam into the South China Sea. These rivers are Nam Ma, Nam Sam, and Nam Neune. The limited information on these rivers restricts assessment of their potential.
Average annual rainfall ranges from 1,300 mm per year in the northern valleys 3,700mm per year at higher elevations in the South. This corresponds to an annual rainfall of 434 billion m³, of which less than half is estimated to be runoff. The Mekong tributaries in Lao PDR contribute some 35% of the whole lower Mekong Basin; annual national supply of renewable fresh water is 270 billion m³, or about 600,000 m³ per person, while current demand is only 259m³/person. Water usage is predominantly agricultural 82%, followed by industrial 10%, and domestic 8%. Usages of other sectors are negligible.There is available water of 270 Billion cubic meters and 5.7 billion has been used and the remaining amount of 264.3 Billion cubic meters flows in the natural rivers.
Currently most of the water use occurs in the agricultural sector such as irrigation, fisheries, plantations and livestock watering. In addition the water is used for hydro-power; the country has the potential to produce 23,000 megawatts of electricity. Currently only 5% of that capacity has been exploited. The plenteous supply of water in Lao PDR, especially in the rainy season, provides good condition for water transport, industrial development and water supply. Sixty percent of urban population and 51 % of rural population has access to clean water.
Currently there are some problems related to waste and polluted water in major urban areas from varied community use (residential density, hotels, hospitals and entertainments centers). In addition there is water pollution from agricultural and industrial sectors, including mineral exploitation. This is not a major problem now, but the problem could escalate. The degradation of natural water and water catchments from sedimentation, land erosion and drying out continues.