The United States - Mexico transboundary aquifer system is an important source of water for public supply, irrigation, and industrial uses. The system is geopolitically defined by the presence of the United States - Mexico international boundary, and contains portions of three regional aquifer systems: (1) the southwest alluvial basins aquifer system, (2) the Edwards - Trinity aquifer system, and (3) the coastal aquifer system (Robson and Banta, 1995; Ryder, 1996).
Working under the auspices of the USGS Water Availability and Use Science Program, TAAP strives to strengthen collaboration with cooperators and stakeholders in the United States and Mexico. These efforts include identifying common interests and opportunities for cost sharing among agencies and institutions. Current studies fall under several categories, including:
TAAP research in the United States is conducted by USGS and the following partnering agencies: International Boundary and Water Commission (IBWC), University of Arizona Water Resources Research Center (WRRC), New Mexico Water Resources Research Institute (WRRI), and Texas Water Resources Institute (TWRI).
Listed below are ongoing USGS studies.
Personnel from the USGS Geology, Minerals, Energy, and Geophysics Science Center (GMEG) are carrying out geologic mapping with Mexican colleagues in some of the more important tributaries to the Santa Cruz River, which includes the Nogales, Sonora area. This is jointly funded by TAAP and the GMEG mapping program.
Benefits: One of the main pumping centers in the Upper Santa Cruz Aquifer underlies the city of Nogales, Sonora. However, the geology there is poorly understood. This task will lead to a better understanding of faulting, rock types, and relationships to geology outside the metropolitan area. Geologic mapping in the Upper Santa Cruz Tributary System will support and improve efforts to model surface water and groundwater in the Santa Cruz Basin by other TAAP researchers.
Vertical geothermal fluid flux will be estimated from temperature profiles and the spatial distribution of upflow zones from heat flow maps. These temperature features will be correlated to mapped faults and estimate the geothermal fluid contribution to the aquifer.
Benefits: Characterizing the amount and spatial distribution of geothermal fluids to the Mesilla Basin aquifers will provide useful information to stakeholders and researchers on the contributions of these geothermal fluids to the Mesilla Basin salt budget, and provide insight into geochemical signatures that would be useful for geochemical modeling and groundwater mixing calculations.
In collaboration with the IBWC and WRRC
The Binational Study of the Transboundary Santa Cruz Aquifer is a binationally-authored report summarizing, developing, and integrating information related to the Upper Santa Cruz Aquifer. The WRRC collaboration includes participation in binational meetings and other tasks required for report review. WRRC will be primarily responsible for mapping corrections.
Benefits: This will collect and publish in one place the first binational summary and synthesis of information on the Upper Santa Cruz Aquifer, one of the aquifers named in the TAAP legislation. This report will contribute to binational development of a model of coupled surface and groundwater in the binational Santa Cruz River Basin.
Groundwater samples will be collected at wells within the Mesilla Basin, which are screened at various depths and represent different spatiotemporal recharge conditions. The geochemical and isotopic composition of the samples will be determined to characterize possible groundwater end members and to calculate volumes of mixing at various locations in the system.
Benefits: This project will provide stakeholders in the region with quantified estimates of deep groundwater contributions to the shallow groundwater and surface-water systems of the Mesilla Basin, and provide stakeholders and water resource managers with information on groundwater movement to inform their management decisions.
Results of the geochemical and isotopic analyses of groundwater in Mesilla and adjoining basins will be added to the National Water Information System (NWIS) database and compiled into the USGS New Mexico Water Science Center investigation of interbasin groundwater exchange.
Benefits: This project will provide stakeholders in the region with quantified estimates of interbasin groundwater exchange of the Mesilla and adjoining basins, and provide stakeholders and water resource managers with information on groundwater movement to inform their management decisions.
A geodatabase is currently being developed by USGS Texas Water Science Center staff in cooperation with the U.S. Army (Ft. Bliss) for the El Paso-Ciudad Juárez area. This geodatabase includes existing water quality, groundwater levels, and geophysical data for wells completed in aquifers of the El Paso-Ciudad Juárez region. Non-sensitive data will be aggregated into a database for TAAP that can be used to assist in developing/upgrading models of groundwater quality and movement, and in identifying data gaps.
Benefits: This user-friendly repository for hydrogeologic data in the El Paso-Ciudad Juárez area can be used for data analyses, future project planning efforts, and to identify data gaps. It will also be used to assist the development of a hydrogeologic framework of the Hueco Bolson aquifer.
Groundwater samples will be collected at wells within the Mesilla Basin, which are screened at various depths and represent different salinities. The geochemical and isotopic composition of the samples will be determined to characterize possible groundwater end-members and to calculate volumes of salinity contributions at various locations in the system.
Benefits: This project will provide stakeholders in the region with quantified estimates of deep groundwater salinity contributions to the shallow groundwater and surface-water systems of the Mesilla Basin, and provide stakeholders and water resource managers with information on distribution of salts to inform their management decisions.
In 2016, 20 Hueco Bolson production wells geospatially distributed throughout the El Paso region were sampled for geochemical analysis. These wells, which belong to Fort Bliss and El Paso Water Utilities, were analyzed for major ions, trace elements, nutrients, pesticides, and selected isotopes.
Benefits: Interpretation of these data will provide insight into groundwater movement and age.
This project is being conducted in conjunction with El Paso Water (EPW). The project will use time domain electromagnetic (TDEM) soundings to generate resistivity profiles near EPW blend wells, which are used to blend pumped groundwater with permeate produced at the Kay Bailey Hutchison Desalination plant. Results will be compared to geophysical logs and in-situ measurements collected by the water utility in 2002-03 to gain insight into spatial and temporal salinity trends.
Benefits: This investigation will assist local groundwater managers and improve understanding of water quality by providing new data regarding salinity trends over time within the Hueco Bolson aquifer.
The USGS and Water Resources Research Centers in Arizona, New Mexico, and Texas will collaboratively produce an interactive digital atlas for the general public. This digital atlas will provide information on the borderlands area, enabling a user to focus on an area of interest to explore details of the landscape and subsurface.
Benefits: The atlas will synthesize information gathered in the course of the TAAP project into a useable, informative product for the general public.
A database of binational San Pedro data will be developed using the USGS ScienceBase platform.
Benefits: This will make the data publically available to all who are interested in the TAAP.
The website will provide a public portal for both data and information about the project. We will use the ESRI Story Map format to tell the story of our work and successes in studying the Binational Transboundary San Pedro Aquifer.
Benefits: This would become the go-to point for the public, decision makers, and researchers wanting to know more about the Binational Transboundary San Pedro Aquifer, and about water use and availability issues along the U.S.-Mexico border.
In collaboration with the WRRC
The WRRC will study the effectiveness of varied approaches in translating and promoting the usefulness of TAAP scientific findings to stakeholders in the United States and Mexico.
Benefits: Results from this project will help the TAAP program effectively communicate necessary scientific information to water managers and natural resource agencies on both sides of the U.S.-Mexico border.