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Impact of Riparian Zone Protection from Cattle on Nutrient, Bacteria, F‐coliphage, Cryptosporidium , and Giardia Loading of an Intermittent Stream
Author(s) -
Sunohara M.D.,
Topp E.,
Wilkes G.,
Gottschall N.,
Neumann N.,
Ruecker N.,
Jones T. H.,
Edge T.A.,
Marti R.,
Lapen* D. R.
Publication year - 2012
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2011.0407
Subject(s) - cryptosporidium , zoology , biology , riparian zone , fecal coliform , coliphage , nutrient , giardia , water quality , pasture , veterinary medicine , ecology , hydrology (agriculture) , environmental science , feces , microbiology and biotechnology , habitat , bacteriophage , escherichia coli , medicine , biochemistry , geotechnical engineering , gene , engineering
This 5‐yr study compared, via an upstream–downstream experimental design, nutrient and microbial water quality of an intermittent stream running through a small pasture (∼2.5 animals ha −1 ) where cattle are restricted from the riparian zone (restricted cattle access [RCA]) and where cattle have unrestricted access to the stream (unrestricted cattle access [URCA]). Fencing in the RCA excluded pasturing cattle to within ∼3 to 5 m of the stream. Approximately 88% (26/32) of all comparisons of mean contaminant load reduction for lower, higher, and all stream flow conditions during the 5‐yr study indicated net contaminant load reductions in the RCA; for the URCA, this percentage was 38% (12/32). For all flow conditions, mean percent load reductions in the RCA for nutrients and bacteria plus F‐coliphage were 24 and 23%, respectively. These respective percentages for the URCA were −9 and −57% (positive values are reductions; negative values are increases). However, potentially as a result of protected wildlife habitat in the RCA, the mean percent load reduction for Cryptosporidium for “all flow” was −321% for the RCA and 60% for the URCA; for Giardia , these respective percentages were −209% (RCA) and 73% (URCA). For “all flow” situations, mean load reductions for the RCA were significantly greater ( p < 0.1) than those from the URCA for NH 4 + –N, dissolved reactive phosphorus (DRP), total coliform, Escherichia coli , and Enterococcus . For “high flow” situations, mean load reductions were significantly greater for the RCA for DRP, total coliform, and Enterococcus . For “low flow” conditions, significantly greater mean load reductions were in favor of the RCA for DRP, total P, total coliforms, fecal coliforms, E. coli , and Enterococcus . In no case were mean pollutant loads in the URCA significantly higher than RCA pollutant loads. Restricting pasturing livestock to within 3 to 5 m of intermittent streams can improve water quality; however, water quality impairment can occur if livestock have unrestricted access to a stream.