When several wetland basins perform this function within a watershed, the effect may be a staggered, moderated discharge, reducing flood peaks. Flood protection may be especially important in cities, where pavement contributes to runoff, and in areas with steep slopes or other land features which tend to increase stormwater amounts and velocity. These functional values can provide economic benefits to downstream property owners and taxpayers. Water Quality Protection Wetland plants and soils have the capacity to store and filter pollutants ranging from pesticides to animal wastes. Calm wetland waters, with their flat surface and flow characteristics, allow particles of toxins and nutrients to settle out of the water column.
Plants take up certain nutrients from the water.
Other substances can be stored or transformed to a less toxic state within wetlands. As a result, our lakes, rivers and streams are cleaner and our drinking water is safer. Larger wetlands and those which contain dense vegetation are most effective in protecting water quality. If surrouding land uses contribute to soil runoff or introduce manure or other pollutants into a watershed, the value of this function may be especially high. Wetlands which filter or store sediments or nutrients for extended periods may undergo fundmental changes.