Date of Award

2023-12-01

Degree Name

Doctor of Philosophy

Department

Interdisciplinary Studies (Sci)

Advisor(s)

Alex S. Mayer

Abstract

The water resources of the United States (U.S.) and Mexico are under tremendous pressure due to declining reservoir levels, changes in climate, and prolonged drought. The U.S.-Mexico border region relies on the Rio Grande and Colorado River, and shared groundwater resources that are transboundary in nature. These resources are vital to the U.S.-Mexico border and are susceptible to drought that leads to reduced flow and allocation to the users. In addition, there are impacts to water quality caused by return flows and from failing sanitation infrastructure. In this study, we focus on 1) the contribution of springs in an area within the international reach of the Rio Grande below Presidio, Texas, and Ojinaga, Chihuahua to just upstream of International Amistad Reservoir, 2) three locations along the U.S.-Mexico border, known as sister cities, Tijuana, Baja California-San Diego, California, Ciudad Juarez, Chihuahua-El Paso, Texas, and Laredo, Texas-Nuevo Laredo, Tamaulipas, and 3) the sharing of these resources to understand the lack of groundwater agreements for transboundary aquifers. A study was conducted in 2022 to estimate the contribution of springs into the Rio Grande for water quantity and quality using Total Dissolved Solids (TDS) to represent salinity that also included ambient water quality data collected from 1995-2022, flow data, and a continuous water quality sensor to measure electrical conductivity. A mass balance was developed to confirm the effects of springs and to evaluate the impacts to the Rio Grande if changes to flow or water quality occur in the Rio Grande or to the springs. The 3 sister cities included the evaluation of deficiencies and evaluating current mechanism used by binational agencies to address the matter. Water quality was evaluated from 1995-2022 to determine if there was a correlation between infrastructure development and changes to water quality using indicator bacteria in the Tijuana River, Pacific Ocean, and the Rio Grande and centered on the binational institutions and strategies used for wastewater infrastructure implementation. In addition to water resources and water quality, the sharing of these resources was investigated to understand the elements that make up groundwater agreements for transboundary aquifers and included a review of international agreements and how they could apply to an agreement along the border. U.S.-Mexico institutions have been studying shared aquifers through the Transboundary Aquifer Assessment Program (TAAP) under a Binational Cooperative Framework. A potential outcome for an agreement on groundwater could be the use of the 1944 Water Treaty and the IBWC to serve as the Commission to administer groundwater. Results of the analysis of springs in the international reach of the Rio Grande showed they contribute to the base flow approximately 6 cubic meters per second and improves water quality below the 1,400 milligram per liter (mg/l) standard. The upper part of the study area experiences low flow conditions with high salinity until reaching the spring complexes. The water quality of the receiving waterbodies in the sister cities had elevated levels of bacteria, indicative of untreated wastewater discharges. The water quality improved when infrastructure was put into place but increased when other issues arose such as collector breaks, pumping issues, and operational issues at the wastewater treatment plants. The agencies addressing binational issues have appropriate mechanisms in place to assist with infrastructure development but need to incorporate operation and maintenance and a fee structure for financing and oversight to promote self-sufficiency and avoid urgent concerns to the communities and environment affected by sanitation issues. The TAAP has proven to be a successful mechanism that could potentially be expanded in scope. The IBWC as an agency independent of groundwater ownership, and its ability to operate international facilities supports the conclusion it can serve as the Commission to implement pilot scale or local binational agreements on groundwater.

Language

en

Provenance

Recieved from ProQuest

File Size

158 p.

File Format

application/pdf

Rights Holder

Gilbert Anaya

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