Phosphorus, Sediment, and Escherichia coli Loads in Unfenced Streams of the Georgia Piedmont, USA
Journal of Environmental Quality , 34 , 2005
Byers, H.L., Cabrera, M.L., Matthews, M.K., Franklin, D.H., Andrae, J.G., Radcliffe, D.E., McCann, M.A., Kuykendall, H.A., Hoveland, C.S., Calvert II, V.H.
Contamination of unfenced streams with phosphorus, sediments, and pathogenic bacteria from cattle activity may be affected by the availability of shade and alternative water sources. The objectives of this study were to evaluate water quality in two streams draining tall fescue (Festuca arundinacea Schreb.)/ common bermudagrass (Cynodon dactylon L.) pastures with different shade distributions, and to quantify the effects of alternative water sources on stream water quality. Loads of dissolved reactive phosphorus (DRP), total phosphorus (TP), and total suspended sediments (TSS) were measured during storm flow, and loads of DRP, TP, TSS, and E.coli were measured every 14 d during base flow in two streams located in the Piedmont region of Georgia. Our results showed that grazing cattle in pastures with unfenced streams contributed significant loads of DRP, TP, TSS, and E. coli to surface waters (p<0.01). Although storm flow was similar in both streams, loads of DRP, TP, and TSS were larger (p< 0.08) in the pasture with the smaller amount of non-riparian shade. Water trough availability decreased (p< 0.08) base flow loads of TSS and E. coli in both streams. Our results indicate that possible best management practices to reduce P, sediment, and E. coli contamination from beef-cattle-grazed pastures would be to develop or encourage non-riparian shade and to provide cattle with an alternative water source away from the stream.