Assessing the ecological implications of the altered flow and sediment regimes within the Rio Grande in Big Bend National Park, Texas




Development of water resources is often at the expense of native aquatic ecological integrity and diversity. Many native riverine species within the Rio Grande have been reduced or eradicated due to the loss of viable and connected habitat, poor water quality, and invasive plants and animals associated with modified flow and sediment regimes. The overall goal of this study is to determine how the modified hydrologic and sediment regimes of the Rio Grande have impacted the aquatic ecosystem structure and function with an emphasis on the native fish diversity remaining in the river. Specifically, we will (1) determine if and how the altered flow regime and increased invasive vegetation have impacted available fish habitat, diversity, and abundance for the Rio Grande in Big Bend National Park (BBNP), (2) identify how the reduced magnitude and frequency of large flood events for the Rio Grande has potentially led to increased periods of turbidity, frequent low oxygen events, and altered associated primary and secondary productivity patterns, and (3) synthesize the state of knowledge for the Forgotten Reach, a dewatered section of the Rio Grande north of BBNP, to identify how ecosystem function might be restored under a different future hydrology for that losing reach (BBNP is a gaining reach in terms of water quantity). Collectively, our research will contribute to the ecological understanding of the Rio Grande and help implement management strategies to increase the amount of water and timing of flows for the Rio Grande on the United States-Mexico border.


  • US Geological Survey – South Climate Science Center
  • US National Park Service
  • US Geological Survey – Utah Cooperative Fish and Wildlife Research Unit (in-kind)


  • Phaedra Budy, Principle Investigator, USGS – UCFWRU – Dept. of Watershed Sciences
  • Brian Laub, Assistant Professor, University of Texas, San Antonio
  • Demitra Blythe, M.S. Candidate, USU – Dept. of Watershed Sciences

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