Rainfall that reaches the ground can be absorbed into the soil or flow over the land. When a wetland is able to capture this water before it enters creeks, streams or rivers, it functions like a natural filter.
First, wetland plants slow the flow of water from the surrounding land. This prevents erosion and gives the roots of wetland plants more time to absorb the nutrients this water is carrying. This also allows suspended sediment to settle to the bottom of the wetland.
By storing water before releasing it slowly, wetlands recharge local groundwater supplies and prevent downstream flooding. By trapping nutrient and sediment pollution, wetlands send cleaner water downstream.