Vegetated Buffer Strips (Swales)

Vegetated Swales, Filter Strips, and Grassed Waterways

Canna in bloom (red flowers) in a vegetated filter strip
Serve as bands of vegetation that either serve as 1) stormwater conveyance systems (Vegetated Swales) that reduce flow velocity and filter sediments (increase sedimentation) from runoff, 2) vegetation bands between nursery production areas and retention ponds that slow runoff and trap sediment, fertilizer, pesticides, and 4) pathogens (potentially) before they enter surface water, and 3) grassed waterways reduce runoff and pestiicide contamination.  
Each of these treatment technologies employs both plant and biological systems to remediate and filter sediment, nutrient, pathogen, and chemical contaminants from runoff to reduce contaminant loading into surface waters.  
Each varies in efficiency based upon site specific conditions, but some generalizations can be made based upon research.

Vegetated Swales

Vegetated swales are typically found in urban communities or along roadsides where the primary runoff source is stormwater.

Vegetated Grassed Swale Effectiveness of Vegetative Swales

Vegetated Filter Strips in Nursery Production

Canna in waterway Vegetative Buffer strip

Grassed Waterways

Grassed waterways can reduce runoff volumes by 47% and herbicide (Isoxaben and Trifluralin - Briggs et al.) residues by 56%.

Isoxaben removal from runoff Vegetated Buffer Width

 

References

Briggs, J.A., Whitwell, T., Riley, M.B., 1999. Remediation of Herbicides in Runoff Water from Container Plant Nurseries Utilizing Grassed Waterways. Weed Technology. 13(1), 157-164.

Briggs, J.A., Whitwell, T., Riley, M.B., 2003. Effect of delayed irrigation on isoxaben and oryzalin runoff from a container nursery. Weed Science. 51(3), 463-470.