Field assessment of bacteria and nutrient removal by vegetative filter strips.

Strategies are sought to reduce the impact of nonpoint sources of pollution, including fecal bacteria, and meet TMDL criteria. Vegetative filter strips (VFSs) are one such strategy, though the data of VFS function under field conditions, particularly for fecal bacteria, are limited. The objective of this study was to evaluate the efficiencies in removing fecal bacteria, N, and P from VFSs installed to treat contaminated runoff from a working feedlot. VFSs were found to be effective in removing a broad range of constituents from beef feedlot runoff pretreated by a settling basin. The first 30 m provided most or all of the reductions found within the 150 m VFSs studied: reductions average 85% of inflow water, 85% of sediment, 77% of N, and 84% of P. Fecal bacteria removal by the VFSs was about one order of magnitude: reductions at 30 m ranged from 83.5% for FC and FS to 91% for E. coli. On the site being studied, this provided an important level of protection and reduced surface-flow concentrations of fecal coliforms to below the 200 CFU/100 mL (coliform-forming units, CFU) water-quality standard for Kansas. [ABSTRACT FROM AUTHOR]