Water Dams Most dams are designed to accomplish a variety of functions, which include flood control, flat water recreation, hydropower electricity generation, and water supply. Although these seem like good reasons for the existence of dams, this type of constructions bring greater negative effects than good ones. The "environment effects of dams include loss of land and biological resources to inundation, reservoir sedimentation and downstream erosion, and hydrological changes unfavorable to many native or desirable species." Dams just strangle rivers and the perfect example of the damage dams cause to rivers is what is happening to the Mekong River in Asia. The Mekong river covers more than 4500 kilometers through 6 countries. It crosses through the Chinis providence of Yunnan, borders Birmania, It divides Thailand and Laos, cuts through Cambodia, passes through South Vietnam, and finally ends in the China Ocean. The Mekong sustains 100 million people, who not only depend on this river for their alimentation or water, but also for irrigation, and for traveling, and sometimes just for recreation. The Thailandese people call it the "Mother "of rivers. Today like many rivers in the world, the Mekong is in danger. The reason is the massive and not well planned construction of dams. These constructions have started to threaten the ecosystem of the river, as well as the subsistence of dozens of communities along its shore. This dams, which have mostly been build last decate, provide energy to southwest Asia. But they also stop the natural migration of fishes, and affect their reproduction and alter the level and quality of water. Some people who live around the river refer to the dams constructions as evil and they say that they have destroyed the happiness of their family. Like in many other places in the world the constructions of dams in the Mekong has caused deforastation, it has destroyed the wild life and has caused the displacement of thousands of poor people who live along the river.