There are many definitions of a riparian buffer. In this post and the video linked here we offer the elements of a well-functioning buffer and show what they look like. Riparian buffers are one of the most effective Best Management Practices to abate non-point source water pollution. The word "riparian" comes from Latin and means "adjacent to water."
I learned about buffers and effective buffer widths when I worked for the Natural Resources Conservation Service but I did not know how important native tree leaves were to the aquatic ecosystem until I heard Dr. Bern Sweeney talk about his research at the Stroud Water Research Center. Did you know that macro invertebrates are “leaf” specific? Visit their website to learn more about it.
Our farm is in the Middle River watershed, at the beginning of the South Fork of the Shenandoah River. It is my belief that if we had well-functioning riparian buffers along all our streams we could de-list our river from the state's dirty water's list or the TMDL (Total Maximum Daily Load). Farmers have been installing riparian buffers for a long time and that is partly why agriculture is half-way in doing its part to restore the Chesapeake Bay. They have done this through voluntary programs like the Conservation Reserve Program and each state's Best Management Practices programs. These are funded through the Farm Bill, EPA, states, and non-profit organizations like the Chesapeake Bay Foundation.
Here's my definition of a riparian buffer: A vegetated area adjacent to a hydric feature capable of reducing the impact of adjacent land uses and providing the hydric feature with sufficient inputs to support a healthy aquatic ecosystem.
Riparian buffers need to be wide enough to do the job which means the plants in the buffer take up or filter out pollutants entering the buffer. Scientists believe the minimum width needs to be somewhere between 35 and 100 feet; this is on both sides of the stream or hydric feature. It needs to be stocked with native trees with a sufficient density to create canopy closure and livestock must be excluded from the buffer area.