Wetlands have the power to clean water. Because water moves more slowly in a wetland and the vegetation is rich and diverse, there’s time and opportunity for physical, chemical, and biological processes to occur. These natural processes remove nutrient contamination, other pollutants, and suspended sediment from the water.
Farm fertilizer and manure, as well as municipal wastewater, add nitrogen and phosphorus to our rivers and streams. If the nitrogen and phosphorus are not removed, they enter our streams and rivers and, eventually, our coastal bays and estuaries.
Marine algae feed on these nutrients, overpopulate, and—as they decompose—siphon oxygen from the water. This creates low-oxygen “dead zones” (hypoxic areas) where aquatic life cannot be supported. The dead zone in the Gulf of Mexico is the largest one affecting the United States and the second largest in the world. Besides the obvious adverse environmental effects, dead zones can have serious economic consequences.