Val Verde County Groundwater Study

The Texas Water Development Board (TWDB) is leading a project to compile the best available scientific information and prepare an overview of the hydrogeology of Val Verde County. This project was requested by Representative Poncho Nevárez, who has facilitated discussions of the water resources issues in the county with various stakeholders. Specifically, Representative Nevárez has requested that the TWDB assemble and analyze available hydrogeologic information concerning Val Verde County, the Devils River, and San Felipe Springs. He also requested that the study assess the feasibility of employing hydrologic triggers to manage the aquifer. The Texas Commission on Environmental Quality and the Texas Parks and Wildlife Department are serving as agency stakeholders for this effort.

This webpage is intended to serve as a clearinghouse for project information and communications. This page links to previous studies and other materials that the TWDB is consulting, described in the annotated bibliography below. We will also post new information generated as the study proceeds, including public testimony and project reports. Finally, we welcome public comments through the TWDB Contact link below.

TWDB Contact

Larry French, P.G.
Director, Groundwater Division
Larry.French@twdb.texas.gov

Project Documents

Letter from Representative Nevárez to TWDB Chair, Bech Bruun, dated February 27, 2017, requesting study on the hydrogeology of Val Verde County.

Letter from Chairman Bruun to Representative Nevárez, dated March 13, 2017, confirming that the TWDB will conduct the requested hydrogeological study.

Study Plan and Schedule

Comments on the TWDB study plan. Remarks made by Dr. Ronald Green at the public information meeting January 24, 2018

Previous studies related to Val Verde County groundwater, listed chronologically

Summary of Investments by the Texas Parks and Wildlife Department in the Devils River Basin. October 2017. Summary of the investigations and monitoring performed by the Texas Parks and Wildlife Department in the Devils River Basin.

Water-Resource Management of the Devils River Watershed, Final Report. August 2017. Southwest Research Institute (SWRI) report evaluating the impact of groundwater pumping in the upper Devils River watershed on downstream discharge in the Devils River using a coupled surface-water/groundwater model.

Priority Groundwater Management Areas and Groundwater Conservation Districts report to the 85th Legislature. January 2017. Texas Commission on Environmental Quality and TWDB report. This report provides information to the executive and legislative leadership on activities undertaken during the preceding two years relating to the creation of groundwater conservation districts (GCDs), the study and designation of priority groundwater management areas (PGMAs), and the operation of GCDs.

Modeling Groundwater Flow to Understand the Water Resources of the Lower Pecos River Watershed. June 2016. Final Report by Southwest Research Institute.

Texas Aquifers Study: Groundwater Quantity, Quality, Flow, and Contributions to Surface Water. December 2016. An atlas of Texas groundwater, updated in 2016 in response to legislative request for information on groundwater quantities, quality, flows between aquifers, and from aquifers to surface waters of Texas.

Focused groundwater flow in a carbonate aquifer in a semi-arid environment. May 2014. Published paper by Dr. Ronald Green.

Hydrogeological Study for Val Verde County & City of Del Rio, Texas, Final Draft Report. May 2014. Report by EcoKai Environmental, Inc. and W.R. Hutchison on the potential impacts of groundwater exports on local spring flows, lake elevations, and groundwater levels using a groundwater flow model. The model was used to 1) estimate the effect of Lake Amistad on groundwater elevations in the area, 2) assess potential management zone delineations, and 3) evaluate the effects of large-scale pumping in three different areas on spring flow, river baseflow, aquifer drawdown, and other changes to the groundwater flow system.

Groundwater Conveyance through Karst Terrains in Semi-Arid Environments. October 2013. Research paper by Dr. Ronald Green.

Evaluation of Hydrochemical and Isotopic Data in Groundwater Management Areas 3 and 7. May 2013. LBG Guyton report to the TWDB using existing hydrochemical and isotope data to assess the conceptual models of the Groundwater Availability Models for the Edwards- Trinity (Plateau), Llano Uplift, and Pecos Valley aquifer systems.

Investigating the Water Resources of the Western Edwards-Trinity Aquifer. June 2010. SWRI report to the Sutton County Groundwater Conservation District undertaken to provide independent determination of “desired future conditions” for the western Edwards-Trinity Aquifer. Water budget analyses were performed for an eight-county area over the western Edwards-Trinity Aquifer. A key conclusion is that Val Verde and Crockett counties are most vulnerable to drought because recharge is negligible when precipitation is less than 16-17 inch/year.

Woody plant encroachment paradox: Rivers rebound as degraded grasslands convert to woodlands. April 2010. Published paper by B. Wilcox.

Groundwater Data Acquisition in Edwards, Kinney and Val Verde Counties, Texas. March 2010. Report by LBG Guyton for the Plateau Regional Water Planning Group and the TWDB to supplement hydrogeological information used in the 2004 Edwards-Trinity GAM. The report includes (1) review of existing aquifer evaluations, field studies and new well data; (2) results of dye tracer tests to analyze groundwater flow direction and speed; (3) new water level measurement during two seasonal periods; and (4) review of recent water quality sampling projects.

Devils River Minnow Recovery Plan. September 2005. U.S. Fish and Wildlife Service report on the recovery strategy for threatened Devils River Minnow. The primary recovery strategy is to reduce threats to the species by protecting naturally functioning spring and stream ecosystems within its current and potentially restorable historic range.

Hydrogeology and Ground-Water Flow in the Edwards-Trinity Aquifer System, West-Central Texas. 2004. U.S. Geological Survey Professional Paper 1421-C. This report is part of the USGS Regional Aquifer System Analysis program. It covers the entire extent of the Edwards-Trinity aquifer in Texas, including the Trans-Pecos, Edwards Plateau, Hill Country, and Balcones Fault Zone sub-regions and provides a broad framework for more local hydrogeological studies.

Amistad National Recreation Area, Texas, Water Resources Scoping Report. September 2001. National Park Service Technical Report NPS/NRWRD/NRTR-2001/295. This report summarizes the available information concerning water resources in the area. The activities of other water related state and federal agencies are described, along with current water quality monitoring programs and studies. The major issues related to water resources are described in detail.

Groundwater Resources of the Edwards Aquifer in the Del Rio Area, Texas. January 2001. This report, funded by the City of Del Rio and the TWDB, evaluates the ground-water resources in the vicinity of Del Rio, focusing on the possibility of completing additional Edwards Aquifer wells to help meet increased demands by the City for water in the future.

Hydrogeologic Framework of the Edwards-Trinity Aquifer System, West-Central Texas. 1996. U.S. Geological Survey Professional Paper 1421-B. This report describes the hydrogeologic framework of the Edwards-Trinity aquifer system, including the depositional, tectonic, diagenetic, and stratigraphic conditions of the rocks that compose the aquifer system, and the hydraulic characteristics, aquifers, and confining units that control groundwater flow.

Groundwater Resources of Val Verde County, Texas. June 1973. TWDB report 172. This report details the hydrogeology, groundwater use and availability, and water quality in Val Verde County, as well as the effects of Lake Amistad impoundment on local groundwater systems.

Presentations

Coupled Surface-Water/Groundwater Evaluation in the Edwards Plateau. October 2017 presentation by Dr. Ron Green and others on the Devils River watershed and theSWRI coupled surface-water groundwater model.

Pecos/Devils River Watershed Projects, Part II. February 2017 presentation by Dr. Ron Green and others on contributions from the Pecos and Devils River watersheds to the Rio Grande and conceptualization of the groundwater systems feeding these rivers.

Edwards-Trinity Aquifer Model Stakeholders Advisory Forum. August 2001 presentation by Roberto Anaya (TWDB), updating Groundwater Availability Modeling stakeholders on groundwater model conceptualization and development.

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