Surface Water Seepage Effects on Shallow Ground-Water Quality Along the Rio Grande in Northern New Mexico1

Authors

  • A.M. Helmus,

    1. Respectively, Graduate Research Assistant (Helmus), Department of Animal and Range Sciences, New Mexico State University, Las Cruces, New Mexico [Helmus now Rangeland Management Specialist, Ashley National Forest, Duchesne, Utah, 84021]
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  • A.G. Fernald,

    1. Associate Professor (Fernald and Abbott), Department of Animal and Range Sciences, MSC 3I, P.O. Box 30003, New Mexico State University, Las Cruces, New Mexico 88003
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  • D.M. VanLeeuwen,

    1. Professor (VanLeeuwen), Department of Agricultural and Extension Education, MSC 3501, P.O. Box 30001, New Mexico State University, Las Cruces, New Mexico 88003
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  • L.B. Abbott,

    1. Associate Professor (Fernald and Abbott), Department of Animal and Range Sciences, MSC 3I, P.O. Box 30003, New Mexico State University, Las Cruces, New Mexico 88003
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  • A.L. Ulery,

    1. Associate Professor (Ulery), Department of Plant and Environmental Sciences, MSC 3Q, P.O. Box 30001, New Mexico State University, Las Cruces, New Mexico 88003
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  • T.T. Baker

    1. Professor (Baker), Department of Extension Animal and Natural Resources, MSC 3AE, P.O. Box 30001, New Mexico State University, Las Cruces, New Mexico 88003.
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  • 1

    Paper No. JAWRA-07-0135-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until October 1, 2009.

(E-Mail/Fernald: afernald@nmsu.edu)

Abstract

Abstract:  Interactions between surface irrigation water, shallow ground water, and river water may have effects on water quality that are important for both drinking water supplies and the ecological function of rivers and floodplains. We investigated water quality in surface water and ground water, and how water quality is influenced by surface water inputs from an unlined irrigation system in the Alcalde Valley of the Rio Grande in northern New Mexico. From August 2005 to July 2006, we sampled ground water and surface water monthly and analyzed for concentrations of major cations and anions, specific conductance, pH, dissolved oxygen, and water levels. Results indicate that irrigation ditch seepage caused an increase in ground water levels and that the Rio Grande is a gaining stream in this region. Temporal and spatial differences were found in ion concentrations in shallow ground water as it flowed from under the ditch toward the river. Ground-water ion concentrations were higher when the ditch was not flowing compared with periods during peak irrigation season when the ditch was flowing. Ditch inputs diluted ion concentrations in shallow ground water at well positions near the ditch. Specifically, lower ion concentrations were detected in ground water at well positions located near the ditch and river compared with well positions located in the middle of an agricultural field. Results from this project showed that ditch inputs influenced ion concentrations and were associated with ground-water recharge. In arid region river valleys, careful consideration should be given to management scenarios that change seepage from irrigation systems, because in some situations reduced seepage could negatively affect ground-water recharge and water quality.

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