Changes in a stream's physical and biological conditions following livestock exclusion
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Authors: D. E. Line
Date: 2003
Journal: Transactions of the American Society of Agricultural Engineers
Volume: 46
Number: 2
Pages: 287-293
Summary of Methods: The Long Creek watershed located in the Piedmont region of southwestern North Carolina was used to evaluate the effectiveness of livestock exclusion fencing and water supply as a best management practice for improving water quality. The Long Creek watershed was divided into an upper pasture (upstream of site D) that was lightly grazed and a heavily grazed lower pasture (between D and E sites) (Line et al., 2000, J Environ Qual:1882-1890 also included in the RSIS). In both pastures an alternate watering system was installed on the ridges, though access by livestock to the stream in the lower pasture was prevented by installation of a riparian corridor fence. Grab samples were collected weekly from April 1993 to March of 2001and analyzed for fecal coliform, fecal enterococci counts, dissolved oxygen, pH, temperature, conductivity, total suspended sediments (TSS) and turbidity.
Article Summary / Main Points: Conductivity, TSS, and turbidity were considerably greater below the heavily grazed pasture than below the lightly grazed pasture prior to fencing and water development, though pH, dissolved oxygen and temperature which were slightly greater below the heavily grazed pasture. Post-fencing, water was warmer, specific conductance increased by only 50% (net decrease of 55%), and turbidity and sediment levels were less across the gradient from the lightly grazed site to the heavily grazed fenced site. After fencing, though fecal coliform counts and enterococci dropped at both sites, counts were still higher in heavily grazed than lightly grazed. Installation of alternative water supplies positively affected all measurements except conductivity and bacteria which were not different between pastures. The installation of only an alternate water supply was not effective at improving water quality.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 136 Southern Piedmont
Agrovoc Control Words: Riparian zones Water quality Nonpoint pollution
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: water pollution, riparian fencing, best management practices (bmp), fecal coliform, alternative water source, watershed
Annotation: The results of this study are applicable to watersheds and riparian areas across the west, though they should be applied with caution as only one stream was tested and each BMP was tested at a different grazing intensity. Further research is required to clearly evaluate the effectiveness of off-site water development alone or paired with fencing the riparian corridor. Additional research has shown that when fencing off a riparian corridor it is important to make it large enough to enable short-term grazing to control weeds that can invade fenced riparian areas.
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