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This article in JEQ

  1. Vol. 41 No. 5, p. 1580-1590
     
    Received: Jan 4, 2012
    Published: September 14, 2012


    * Corresponding author(s): pat.clark@ars.usda.gov
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doi:10.2134/jeq2012.0005

Water Quality Effects of Herded Stream Crossings by Domestic Sheep Bands

  1. Patrick E. Clark *a,
  2. Corey A. Moffetb,
  3. Gregory S. Lewisc,
  4. Mark S. Seyfrieda,
  5. Stuart P. Hardegreea and
  6. Fredrick B. Piersona
  1. a USDA–ARS, Northwest Watershed Research Center, 800 E. Park Blvd., Suite 105, Boise, ID 83712
    b The Samuel Roberts Noble Foundation, 2510 Sam Noble Pkwy., Ardmore, OK 73401
    c USDA–ARS, U.S. Sheep Experiment Station, 19 Office Loop, Dubois, ID 83423

Abstract

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.

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Copyright © 2012. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.