The Amazon has a total area of 6.15 million km2. It is runs through seven countries; Brazil (63.9 percent), Peru (15.6 percent), the Plurinational State of Bolivia (11.7 percent), Colombia (5.6 percent), Ecuador (2.1 percent), the Bolivarian Republic of Venezuela (0.9 percent) and Guyana (0.2 percent). The Amazon River starts at the Mantaro River. The Mantaro River is its source. It empties into the Atlantic Ocean. The river is 6,437 kilometers long, which is 4,000 miles. The river flows through the largest forest in the world, the Amazon Rainforest. Even though many people think that the Nile is longer than the Amazon, Brazilian scientists proved that the amazon is, in fact, the longest river in the world. Not many people live near the Amazon River since there is a forest that surrounds it. A few of the people that live near the Amazon are Yanomamo and Kayapo have been living there for thousands of years. They now share it with people who use the Amazon rainforest’s natural resources. In recent decades, there has been an accelerated process of immigration into the Amazon River basin. In 1999, the Amazon population was estimated at 23 million inhabitants, of which 49 percent in Brazil, 30 percent in Peru, 15 percent in Bolivia, 3 percent in Colombia and 3 percent in Ecuador. There are many uses for the Amazon River. For example, people use it for food. There are over 3,000 species of fish in the river. These fish could also attract land animals near the water and make it easier to hunt them. The Amazon also has 20 percent of the world’s freshwater. There are 48 dams on the amazon of more than 2 megawatts already. There are 150 more planned in the next two decades. With that said, many of these dams block fish migrations, which in some cases if a species is completely separated, might end that species. Another problem is that when the flow of a river slows, the temperatures of the rivers get warmer. The change in temperature means a decline in fish populations, as the eggs are not able to mature. When the river gets warmer the pH of the river changes, which leads to decline in local plant and animals species that can’t easily adapt to these changes. There are many more environmental problems that dam cause.