Prepared in cooperation with the U.S. Army Corps of Engineers, New Mexico Interstate Stream Commission, Texas Commission on Environmental Quality, and Texas Water Development Board Pecos River Basin Salinity Assessment, Santa Rosa Lake, New Mexico, to the Confluence of the Pecos River and the Rio Grande, Texas, 2015 Scientific Investigations Report 2019–5071 U.S. Department of the Interior U.S. Geological Survey Background, Pecos River above Santa Rosa Dam, New Mexico, upstream view. Photograph by Daniel Sinclair, U.S. Geological Survey, February 2015. Front cover: Top, Lea Lake at Bottomless Lakes State Park, New Mexico. Photograph by Johnathan Bumgarner, U.S. Geological Survey, October 2011. Left, Pecos River at Independence Creek, Texas, downstream view. Photograph by Johnathan Bumgarner, U.S. Geological Survey, January 2012. Right, Pecos River at Old Crane Road bridge, Texas, downstream view. Photograph by Christopher Braun, U.S. Geological Survey, February 2015. Back cover: Left, Pecos River at Red Bluff Reservoir outflow, Texas, downstream view. Photograph by Johnathan Bumgarner, U.S. Geological Survey, October 2011. Right, Bitter Lake National Wildlife Refuge south weir inflow, New Mexico, downstream view. Photograph by Daniel Sinclair, U.S. Geological Survey, February 2015. Bottom, Pecos River near Malaga, New Mexico, downstream view. Photograph by Daniel Sinclair, U.S. Geological Survey, February 2015. Pecos River Basin Salinity Assessment, Santa Rosa Lake, New Mexico, to the Confluence of the Pecos River and the Rio Grande, Texas, 2015 By Natalie A. Houston, Jonathan V. Thomas, Patricia B. Ging, Andrew P. Teeple, Diana E. Pedraza, and David S. Wallace Prepared in cooperation with the U.S. Army Corps of Engineers, New Mexico Interstate Stream Commission, Texas Commission on Environmental Quality, and Texas Water Development Board Scientific Investigations Report 2019–5071 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior DAVID BERNHARDT, Secretary U.S. Geological Survey James F. Reilly II, Director U.S. Geological Survey, Reston, Virginia: 2019 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit http://www.usgs.gov/pubprod/. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Houston, N.A., Thomas, J.V., Ging, P.B., Teeple, A.P., Pedraza, D.E., and Wallace, D.S., 2019, Pecos River Basin salinity assessment, Santa Rosa Lake, New Mexico, to the confluence of the Pecos River and the Rio Grande, Texas, 2015: U.S. Geological Survey Scientific Investigations Report 2019–5071, 75 p., https://doi.org/10.3133/sir20195071. Associated data for this publication: Houston, N.A., Thomas, J.V., Pedraza, D.E., Ging P.B., Teeple, A.P., and Wallace, D.S., 2019, Water quality, streamflow gain loss, geologic, and geospatial data used in the Pecos River salinity assessment from Santa Rosa Lake, New Mexico to the confluence of the Pecos River and the Rio Grande, Texas, 1900–2015: U.S. Geological Survey data release, https://doi.org/10.5066/F7DB800T. ISSN 2328-0328 (online) iii Acknowledgments The authors thank Robin Prewitt with the Red Bluff Water Power Control District for assistance with access to the Red Bluff Reservoir and irrigation canals for reconnaissance and information related to reservoir releases in conjunction with water-chemistry sampling. The authors thank Paul Weatherby and Ty Edwards with the Middle Pecos Groundwater Conservation District for sharing their expertise and for their assistance identifying water-quality sampling locations. The authors also thank Lewis Land, the New Mexico Bureau of Geology and Mineral Resources; Alyson McDonald, Texas A&M AgriLife Extension Center; and Ernest Woodward, Pecos County Water Improvement District No. 3, for sharing their expertise of the Pecos River Basin and providing access to areas of interest in the Pecos River Basin for the Pecos River salinity assessment team members in November 2014 and April 2015. In addition, the authors thank former commissioners Rick Rylander and J.W. Thrasher of the Pecos River Commission for sharing their expertise of the Pecos River Basin. v Contents Abstract ..........................................................................................................................................................1 Introduction ....................................................................................................................................................2 Purpose and Scope .............................................................................................................................3 Description of the Study Area ...........................................................................................................3 Geologic and Hydrogeologic Setting ................................................................................................6 Pecos Valley Aquifer ................................................................................................................12 High Plains Aquifer ...................................................................................................................12 Edwards-Trinity Aquifer System .............................................................................................12 Dockum Aquifer .........................................................................................................................13 Rustler Aquifer ...........................................................................................................................13 Capitan Reef Aquifer ................................................................................................................13 Roswell Basin Aquifer System ...............................................................................................13 Methods ........................................................................................................................................................14 Geologic and Hydrogeologic Data Compilation ............................................................................14 Natural Gamma Logs ................................................................................................................14 Electric Logs ..............................................................................................................................14 Electromagnetic Induction Logs ............................................................................................15 Hydrogeologic-Unit Mapping Methods .........................................................................................15 Historical Water-Quality Data Compilation and Review ..............................................................15 Data Sources .............................................................................................................................16 Data Compilation and Comparison ........................................................................................16 Data Quality Assurance ...........................................................................................................16 Streamflow Measurement Methods ..............................................................................................17 Water-Quality Sampling Methods ...................................................................................................17 Water-Quality Analysis Methods ....................................................................................................19 Quality Assurance and Control of Water-Quality Data ................................................................24 Data Release .......................................................................................................................................24 Pecos River Basin Salinity Assessment .................................................................................................25 Previous Salinity Studies by Reach ................................................................................................25 Santa Rosa Lake to Puerto de Luna—Subreach in Reach A ............................................25 Acme to Artesia—Subreach in Reach B ..............................................................................25 Malaga to Pierce Canyon Crossing—Subreach in Reach C .............................................26 Red Bluff Reservoir to Confluence of Rio Grande and Pecos River—Reach D .............28 Other Sources of Salinity in the Pecos River Basin .....................................................................29 vi Mapped Geologic Units and Their Relation to Salinity of the Pecos River Basin ...................30 San Andres Limestone .............................................................................................................30 Artesia Group .............................................................................................................................31 Grayburg Formation .........................................................................................................31