Forgotten Reach of the Rio Grande, Fort Quitman To Presidio, Texas Section 729 January 2008 Prepared by: US Army Corps of Engineers for the Albuquerque District i This page left intentionally blank Table of Contents Chapter 1 – Overview.................................................................................................................. 1 1.1 Study Authority and Reconnaissance Study ................................................................. 3 1.2 Feasibility Study................................................................................................................. 3 1.3 Local Sponsor’s Support................................................................................................... 5 1.4 Watershed Planning Goals, Methods, Objectives and Constraints........................... 5 1.4.1 Planning Goals ........................................................................................................... 5 1.4.2 Planning Methods ...................................................................................................... 5 1.4.3 Planning Objectives ................................................................................................... 6 1.4.4 Planning Constraints.................................................................................................. 6 1.5 Existing Studies.................................................................................................................. 7 Chapter 2 – Study Area Description.......................................................................................... 8 2.1 Study Area Definition......................................................................................................... 9 2.2 History and Population.................................................................................................... 11 2.2.1 Climate....................................................................................................................... 11 2.2.2 Physiography and Geology .................................................................................... 12 2.2.3 Soils............................................................................................................................ 13 2.2.4 Watershed Stakeholders......................................................................................... 14 Chapter 3 – Geomorphology and Sediment Cones ............................................................. 17 3.1 Hydrology .......................................................................................................................... 18 3.2 River Channel Geomorphology and Cross Section Changes .................................. 28 3.3 Sedimentation Observations within the Forgotten Reach......................................... 33 3.3.1 Limitations ................................................................................................................. 33 3.3.2 Qualitative Geomorphic Response ....................................................................... 33 3.3.3 GIS Assessment of Sediment Cones.................................................................... 35 Chapter 4 – Environmental Resources................................................................................... 40 4.1 Water Quality.................................................................................................................... 42 4.2 Groundwater..................................................................................................................... 44 4.3 Vegetation......................................................................................................................... 45 4.4 Wetlands ........................................................................................................................... 54 4.5 Wildlife ............................................................................................................................... 55 4.5.1 Ichthyofauna.............................................................................................................. 56 4.5.2 Mollusks and Crustaceans...................................................................................... 56 4.5.3 Federally or State Listed Species.......................................................................... 57 Chapter 5 – Problems and Opportunities............................................................................... 60 5.1 Problems ........................................................................................................................... 61 5.2 Opportunities .................................................................................................................... 62 Chapter 6 – Recommendations ............................................................................................... 64 6.1 Recommendations........................................................................................................... 65 6.1.1 General Recommendations:................................................................................... 65 6.1.2 Construction of a Conceptual Model of Rio Grande Channel Forms .............. 67 i 6.2 Pilot Projects..................................................................................................................... 68 6.2.1 Project Components ................................................................................................ 68 6.2.2 Design of Pilot Projects........................................................................................... 71 Chapter 7 – References............................................................................................................ 74 Chapter 8 – Appendices............................................................................................................ 78 Appendix A – Observation Notes on Sediment Cones..................................................... 79 Appendix B – The University Of Texas Center For Space Research Summary Information ......................................................................................................................... 86 Appendix C – Species Found within the Forgotten Reach ............................................ 106 Appendix D – La Junta Project Saltcedar Biological Control in Forgotten Reach of Rio Grande: Vegetation Canopy Cover and Frequency within 100m diameter Bird Point Count Plots....................................................................................................................... 117 Appendix E – Bird Monitoring at Saltcedar Beetle Release Sites, Rio Grande, Candelaria, Presidio County Texas, 2007 .................................................................. 145 ii Figures Figure 1 - Map showing area of the Forgotten River. .................................................... 10 Figure 2 - Fort Quitman IBWC gage in the rectified channel at the upper end of the Forgotten Reach looking downstream...................................................................... 19 Figure 3 - Candelaria IBWC Gage upstream of Capote Creek and Candelaria, Texas, January 2007. Note aggradation from influence of San Antonio Diversion Dam (Mexican) just downstream and San Antonio arroyo confluence just upstream. ...... 20 Figure 4 - Confluence of the Green River with the Rio Grande (42 river miles downstream of Indian Hot Springs, Texas). Note the sediment plug. Photo February 2007. ........................................................................................................................ 24 Figure 5 - Upstream view of the Rio Grande and Green River confluence showing relative elevation of sediment plug and abrupt change in gradient of the Rio Grande; looking upstream. Photo February 2007. ................................................................ 24 Figure 6 - Average Peak Monthly Volumes at El Paso and Presidio (Pre- and Post- Elephant Butte Construction).................................................................................... 27 Figure 7 – A narrow, single-thread channel, almost ditch-like in appearance and function, has been vegetatively reinforced by the root system of the saltcedar which line it. This phenomenon is repeated at intervals along the entire Forgotten Reach. ................................................................................................................................. 30 Figure 8 - A myriad of small channels as a result of sediment aggradation and saltcedar establishment characterize much of the Forgotten Reach. Areas like these comprise thousands of acres and are responsible for attenuation of flows. (USGS, 1996) ..... 31 Figure 9 - Below Candelaria, the Forgotten Reach has a narrow, defined channel (foreground) at low flows, but transforms into a myriad of channels through an aggraded floodway at high flows, Photo taken looking upstream January 2007. ... 31 Figure 10 - An avulsion out of a vegetatively reinforced and aggraded channel into an adjacent Bermuda grass pasture upstream of Indian Hot Springs demonstrates the tentative nature of the channel through the Forgotten Reach. Photo taken January 2007. ........................................................................................................................ 32 Figure 11 – Combined U.S. and Mexico Arroyo Sediment Deposition by Activity level. 37 Figure 12 - Distribution by activity level, U.S................................................................. 37 Figure 13 - Distribution by activity level,