Floodplain wetlands, also known as "riverine" or "riparian" wetlands, occur in the floodplain along the sides of non-tidal streams. Many streams and rivers have been dammed to form impoundments or mill ponds, like Killens Pond on the Murderkill River, Silver Lake on the St. Jones River, Haven Lake on the Mispillion River, and Collins Pond on the Nanticoke River. Remaining riverine areas feature a mix of deciduous trees, including red maple, sweet gum, black gum, willow oak, pin oak, and others.

These wetlands play a critical role in absorbing runoff water and then slowly releasing it before it reaches rivers and streams, thus reducing downstream flooding. The photo below on the right shows an area just south of Silver Lake in Dover after it was flooded by Hurricane Irene in 2011. Because this area was converted from a wetland, it is no longer equipped to accommodate large volumes of water input in a short time span, like from precipitation during storms.

Like other wetland types, riverine wetlands also provide vital wildlife habitat, adding to their conservation value. Encroachment by nearby developments and a lack of buffer requirements threaten riverine wetlands through direct and indirect impacts, respectively.

Piedmont stream valley wetlands occur within stream valleys of the Piedmont area in northern New Castle County. These wetlands develop on floodplains of creeks and streams, often near the base of steep, wooded slopes, and are typically saturated year-round. Soils are usually deep organic muck, but gravel may be present underneath. Piedmont valley streams can vary in size and position on the landscape and can either be sunny with an open canopy or shady with a closed canopy. This means that the types of plant and animal species that are found in these areas can be very diverse.

Are we speaking a different language? Try the Wetlands Glossary.

Check out the new Delaware Wetland Plant Field Guide and data on the Condition of Tidal and Non-Tidal wetlands.