Long-term effectiveness and maintenance of vegetative filter strips

Vegetative filter strips (VFS) on 33 Virginia farms were visited and observed over a 13-month period to evaluate their long-term effectiveness for water quality improvement. Operational problems observed during the site visits were documented and design or maintenance procedures to alleviate the problems were evaluated. Of the VFS observed, 36% were judged to be totally ineffective, were no longer in existence, or were simply extensions of pastures - although all were, or had been, part of the state cost-share program.

Most of the sites visited had topographic limitations which severely limited VFS performance. Accumulation of surface runoff in natural drainageways within fields before it reached the VFS was the most common and critical problem. Runoff from the drainageways crossed the VFS in a few narrow areas, totally inundating the filters and rendering them ineffective for sediment and nutrient reduction. This situation is difficult to control and VFS are probably not appropriate for fields with extensive internal drainageways unless the VFS extend up into the fields and parallel the drainageways forming wide grassed waterways.

Vegetative filter strips were judged to be beneficial even when they could not filter sediment and nutrients from runoff because they provided localized erosion protection in critical areas along streambanks. They did not act as filters, however, and should therefore be referred to as vegetative buffer strips or critical area plantings.