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Water Quality Effects of Herded Stream Crossings by Domestic Sheep Bands
Author(s) -
Clark Patrick E.,
Moffet Corey A.,
Lewis Gregory S.,
Seyfried Mark S.,
Hardegree Stuart P.,
Pierson Fredrick B.
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/jeq2012.0005
Subject(s) - environmental science , water quality , hydrology (agriculture) , rangeland , streams , total suspended solids , suspended solids , stocking , livestock , upstream and downstream (dna) , zoology , ecology , upstream (networking) , biology , environmental engineering , geology , agroforestry , computer network , chemical oxygen demand , geotechnical engineering , wastewater , computer science
Livestock impacts on total suspended solids (TSS) and pathogen (e.g., Escherichia coli ) levels in rangeland streams are a serious concern worldwide. Herded stream crossings by domestic sheep ( Ovis aries ) are periodic, necessary managerial events on high‐elevation rangelands, but their impacts on stream water quality are largely unknown. We evaluated the effects of herded, one‐way crossings by sheep bands (about 2000 individuals) on TSS and E. coli concentration and load responses in downstream waters. Crossing trials were conducted during the summers of 2005 and 2006 on two reaches within each of three perennial streams in the Centennial Mountains of eastern Idaho and southwestern Montana. Water samples were collected at 2‐min intervals at an upstream background station and at stations 25, 100, 500, and 1500 m downstream just before and during each crossing trial. Crossings produced substantial increases in TSS and E. coli concentrations and loads downstream, but these concentration increases were localized and short lived. Maximum TSS concentration was highest 25 m downstream, declined as a function of downstream distance, and at 500 m downstream was similar to background. Post‐peak TSS concentrations at all downstream stations decreased to <25 mg L −1 within 24 to 48 min after reaching their maxima. Findings for E. coli concentration and load responses were similar to that of TSS but less clear cut. Stream‐crossing sheep do affect water quality; therefore, producers and resource managers should continue to evaluate the efficacy of herdsmanship techniques for reducing water quality impact.