A generation ago, wetlands were considered a nuisance. They were drained and filled in, then farmed or built on. Today, we know better than to erase these valuable ecosystems from our coastal and inland landscapes.” (Waterwise, Winter 1995)
Wetlands naturally clean water to help keep our rivers, streams, and oceans clean. Both the extensive root mass of the plants and the soil itself work together to extract contaminants and nutrients from the water.
Sand dunes act as natural soil filters for contaminants and nutrients found in water that is ocean bound. Nutrients, such as nitrogen, become food for microorganisms. Sand represents just one type of soil filter. Gravel, brick, and earth also filter soil, while combinations of these soils can provide more extensive filtering.
Natural wetlands and soil filters such as sand dunes do not have the capacity to clean water contaminated by humans and industry. For this purpose, we can learn from nature and imitate her by building constructed wetlands, contained soil filters, and other designed ecosystems for the purpose of purifying human, agricultural, and industrial wastewater.
We have come to understand the many functions of natural wetlands and the importance of preserving them. Most notably, wetlands serve as water purifiers and as refuge for hundreds of plant and animal species, including endangered species. Wetlands also perform other essential functions, including the prevention of shoreline erosion and flooding. (See Watersheds, North Carolina State University – WWW). For these reasons, national measures have been crafted to protect and restore these fragile systems. (See Wetlands Assistance Guide for Landowners – WWW.)
The federal regulations implementing Section 404 of the Clean Water Act (WWW) define wetlands as:
Those areas that are inundated or saturated by surface or ground water (hydrology) at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation (hydrophytes) typically adapted for life in saturated soil conditions (hydric soils). Wetlands generally include swamps, marshes, bogs, and similar areas (40 CFR 232.2(r)).