Get Email Updates

What's a Riparian Area?

By Carol Shé, Northeast Regional Office Habitat Conservation Division

Stony Brook watershed. Photo credit: NOAA

Plymouth, MA. Photo credit: NOAA


A riparian area is the border between a waterway and the land. In plain language, riparian means river bank. The riparian area is made up of vegetation that is adapted to wet conditions.  This invaluable habitat provides important natural filters that protect aquatic environments from excessive erosion and polluted surface runoff. Riparian areas also provide shelter and food for numerous aquatic animals. Overhanging vegetation also provides shade above waterways, which helps control water temperature.

The loss of riparian areas due to clearing for farming or from grazing animals can have a serious impact on the watershed. For instance,  land-based nutrients, which come from fertilized farmlands, pesticides to control insects, manure from animals or irrigation waters that  normally would be filtered and trapped by riparian vegetation  can flow freely into the waterway.   Nutrients decrease the amount of oxygen in the water by spurring on algae blooms which eventually die and deplete the oxygen when they decay. Most fish species require high oxygen levels in the water to survive. High nutrient levels can also affect plants such as eel grass and other submerged aquatic vegetation which serve as food and shelter for fish. Fecal material from farm animals contains bacteria, viruses and microscopic organisms that can negatively affect fish and shellfish and our ability to consume them. Runoff from erosion of stream banks, roads, and ditches causes increased sedimentation that prevents sunlight from reaching plants, interfering with their growth, while turbidity (when particles and sediment are stirred up in the water) can clog and harm the gills of fish, cover shellfish, and prevent larvae from settling. Increases in water temperatures can also result when riparian vegetation is removed, which affects the ability of fishes to inhabit those waters and reproduce.  

When we consult with other federal agencies on agricultural activities that could affect essential fish habitat, we usually recommend a set of “best management practices” to minimize negative impacts on rivers and streams from agricultural activities. By requiring that riparian buffer zones remain undisturbed along the waterway, runoff from erosion and chemicals can be prevented.  Destruction by farm animals can be stopped by requiring that fences be installed along the buffer zone. This prevents animals from grazing on the vegetation. We may also require that fecal holding basins be sited far enough away so that the sewage does not enter the stream. New technologies for irrigation systems decrease the amount of water needed, thereby reducing runoff which can occur when there is excessive watering of crops. Agricultural roads can be constructed away from streams and erosion controlled by planting vegetation next to the roads.  Ditches can be constructed to decrease erosion by lining them with cobble stones that slow rainwater, allowing it to drain before reaching the waterway.

Currently, we are working with staff from the Natural Resources Conservation Service in Maine to develop a comprehensive document to streamline the regulatory review process by ensuring that appropriate “best management practices” are utilized for farm and agricultural practices.  The use of best management practices will make it easier for a proposed project to move forward quickly in the regulatory process while still ensuring that essential fish habitat is protected.