AMISTAD NATIONAL RECREATION AREA, TEXAS WATER RESOURCES SCOPING REPORT Carol E. Purchase. David Larson, Mark D. Flora, and John Reber Technical Report NPS/NRWRD/NRTR-2001/295 United States Department of the Interior • National Park Service The National Park Service Water Resources Division is responsible for providing water resources management policy and guidelines, planning, technical assistance, training, and operational support to units of the National Park System. Program areas include water rights, water resources planning, regulatory guidance and review, hydrology, water quality, watershed management, watershed studies, and aquatic ecology. Technical Reports The National Park Service disseminates the results of biological, physical, and social research through the Natural Resources Technical Report Series. Natural resources inventories and monitoring activities, scientific literature reviews, bibliographies, and proceedings of technical workshops and conferences are also disseminated through this series. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the National Park Service. Copies of this report are available from the following: National Park Service (970) 225-3500 Water Resources Division 1201 Oak Ridge Drive, Suite 250 Fort Collins, CO 80525 National Park Service (303) 969-2130 Technical Information Center Denver Service Center P.O. Box 25287 Denver, CO 80225-0287 ii AMISTAD NATIONAL RECREATION AREA TEXAS WATER RESOURCES SCOPING REPORT Carol E. Purchase1, David Larson2, Mark D. Flora3 and John Reber4 Technical Report NPS/NRWRD/NRTR-2001/295 September, 2001 1 National Park Service, Big Bend National Park, Texas 2 National Park Service, Amistad National Recreation Area, Del Rio, Texas 3 Water Resources Division, National Park Service, Fort Collins, Colorado 4 Intermountain Support Office, National Park Service, Denver, Colorado United States Department of the Interior National Park Service Table of Contents Executive Summary ...............................................................................................................1 Acknowledgments ..................................................................................................................3 Introduction.............................................................................................................................4 Legislative / Operational framework..................................................................................4 Purpose & Management Objectives of Amistad NRA ......................................................6 Compacts and Treaties .....................................................................................................7 Reservoir Operations ........................................................................................................9 Water Rights....................................................................................................................11 Fisheries Management Plan ...........................................................................................13 Watershed Description.........................................................................................................14 Climate.............................................................................................................................14 Geology ...........................................................................................................................14 Soils .................................................................................................................................15 River Environments .........................................................................................................15 Vegetation and Shoreline environment...........................................................................19 Groundwater....................................................................................................................21 Springs and Seeps ..........................................................................................................21 Water Flows .........................................................................................................................25 Introduction......................................................................................................................25 Rio Grande above Amistad.............................................................................................26 Pecos River .....................................................................................................................27 Devils River .....................................................................................................................27 Amistad Reservoir ...........................................................................................................29 Rio Grande Below Amistad.............................................................................................31 Water Quality........................................................................................................................32 Introduction......................................................................................................................32 Current Water Quality Monitoring Programs ..................................................................32 Planned and Ongoing Water Quality Studies .................................................................33 Summary And Trends In Water Quality..........................................................................36 Fisheries/Aquatic Biological Resources..........................................................................43 Water-Related Resource Issues..........................................................................................46 Salinity .............................................................................................................................46 Nutrients ..........................................................................................................................47 Metals and Trace Elements ............................................................................................47 Algae and Algae blooms .................................................................................................48 Organic Compounds .......................................................................................................50 Bacteria............................................................................................................................50 Water Quality during Flood Events .................................................................................50 Fluctuating Reservoir Water Levels................................................................................51 Exotic Species.................................................................................................................55 Land Use Development Around The Reservoir..............................................................59 i Hazardous Material Transport / Spill Contingency Planning..........................................63 Riparian Zones of Amistad NRA.....................................................................................65 Reservoir Siltation ...........................................................................................................66 Recreational Issues Related to Water Resources..........................................................66 Marina Operations and Maintenance..............................................................................70 Amistad NRA Facilities Issues ........................................................................................72 Fisheries Issues...............................................................................................................76 Considerations For Future Actions ......................................................................................79 References ...........................................................................................................................84 Appendix 1: List of Abbreviations used in this report ..........................................................90 Appendix 2: Amistad NRA Checklist of Fish Species: .......................................................91 TABLES Table 1. Campground and Boating Use Levels....................................................................7 Table 2. Major Springs within Amistad NRA.......................................................................23 Table 3. Active Water Quality Monitoring Stations .............................................................35 Table 4. Impairment status for stream segments in the Amistad NRA. .............................36 Table 5. Water Quality Standards for Waters in the Amistad NRA....................................37 Table 6. Average and Range of Selected Water Quality Parameters for Water Quality Monitoring Stations in the Amistad Area ......................................................................38 Table 7. Historical Fish Stocking Records of the Texas Parks and Wildlife Department for the United States Portion of Amistad Reservoir. ....................................................45 Table 8. 1998 Commercial Fish Harvest Records of SEMARNAP for the Mexican Portion of Amistad Reservoir ....................................................................................................45