Water quality improvement is a positive service attributed to wetlands that absorb and recycle nutrients from human settlements. The denitrification potential of wetlands is often surprisingly high. As much as 2,000 to 3,000 kg of nitrate-nitrogen can be denitrified per hectare of wetlands per year, depending on the hydraulic conditions. This is important for the protection of surface waters because a significant amount of nitrate is released by agricultural activities. As much as 100 kg nitrate-nitrogen per hectare may be found in the drainage water from intensive agriculture. Since the denitrification is accompanied by the oxidation of organic matter, this process also removes a significant amount of organic matter