Ducks and geese make wetland marshes their nesting place. And species as diverse as the high-diving osprey, the muskrat, and voles and shrews can be found there. Beyond providing valuable wildlife habitat, wetlands also perform less noticeable functions. Wetlands along rivers and flood plains help regulate stream flow by storing water during periods of high runoff and heavy rainfall. By slowly releasing the water back into the surrounding environment, the frequency, level, and velocity of floods and riverbank erosion are reduced.
Wetlands also provide a natural water filtration process.
For example, they can trap sediments and filter metals and organic polluntants like sewage and agricultural waste. This cleansed water is then released back into springs, streams, and aquifers that feed the tributaries. As water is absorbed and held by the forest, it reduces the amount of overland runoff that can lead to soil erosion. The severity of flooding, and the amount of sediment washing into rivers, lakes, and reservoirs can be regulated or reduced to some degree by healthy forests. As this map developed by the U.S. Department of Forest Service shows, only parts of the Northwest contain densely forested areas.