the kidneys of the river system
wetlands are low-lying areas through which rivers spread put and run slowly. they are important as they hold on to water and act as a buffer when rainfall is low. Much of a river's sediment is deposited here, so wetlands are very productive and attract a rich diversity of wildlife. wetlands are also a natural filter, extracting many of the pollutants that enter a river from industry and other human activities. Despite their importance, wetlands are constantly being destroyed as land is drained and reclaimed for human use.