Today, these Type I and Type III wetlands are known as the Prairie Pothole Region of North Dakota, considered to be the most productive ecosystem on Earth. Type IV and V wetlands are simply deeper depressions that hold more water. Some of these wetlands may be located within a larger watershed, meaning that more water may run into the wetland, keeping the water quite deep. The Prairie Pothole Region is a 300,000 square-mile ecosystem that supports more than 200 species of migratory birds. Yet, many people may overlook the other valuable aspects of wetlands.
Wetlands are important water storage areas, especially for the heavy rains of spring.
They act as a natural sponge to hold water. The water is released slowly, helping prevent flooding of streams and river valleys. In some areas, wetlands renew or recharge ground water systems that feed into people's wells. Wetlands trap sediment that may erode from upland areas. This prevent silt from clogging up the streams and filling in the lakes.