Fall 2023 - 60990 - PA 680PA - Policy Research Project


Instructor: Miguel Pavon (formerly David Eaton)

Client: Texas Commission on Environmental Quality (TCEQ) and CONAGUA, Mexico’s federal water agency

Meets: Tuesday 6-9PM

The purpose of the 2023-34 PRP is to conduct a thorough and robust salinity analysis in the LRG/RB and use the information to develop recommendations for Mexican, Texas and US agencies for improving water quality in the LRG/RB. 


One of the most productive elements of US-Mexican relations in 2023 is trans-boundary environmental quality, particularly between Texas and its four bordering Mexican states, Tamaulipas, Nuevo Leon, Coahuila, and Chihuahua. The two nations have worked together effectively for decades since the North American Free Trade Agreement to reduce air, water, solid and hazardous waste pollution, improve the border air and water quality, and address (but by no means resolve) water quantity and access conflicts. One of the reasons for the success in reducing pollution and improving ambient environmental quality along the Texas-Mexico border is the close cooperation between Texas and its Mexican border states through initiatives such as Border 2000, Border 2012, Border 2020 and now Border 2025, with Texas taking the institutional lead for two regional cooperative processes, the so-called four-state (Texas, Tamaulipas, Nuevo Leon and Coahuila) and three-state (Texas, New Mexico and Chihuahua).  

The class is working with the Texas Commission on Environmental Quality (TCEQ), the environmental agency for the State of Texas and CONAGUA, Mexico’s federal water agency. CONAGUA, Mexico’s National Water Commission is an administrative and technical agency within Mexico's Ministry of the Environment and Natural Resources (SEMARNAT). CONAGUA administers national waters, manages and controls the country's hydrological system, and promotes social development. TCEQ’s headquarters are located at 12100 Park 35 Circle in Austin. TCEQ is the fourth largest environmental agency in the United States (behind the US Environmental Protection Agency, the California EPA, and the New York DEC). TCEQ employs approximately 2,780 employees, has 69 regional offices, and had a $378 million operating budget for the 2021 fiscal year. Its mission is: “The Texas Commission on Environmental Quality strives to protect Texas’ public health and natural resources, consistent with sustainable economic development.” TCEQ’s goal is clean air, clean water, and the safe management of waste.  

The class will work with TCEQ, CONAGUA, the U.S. Environmental Protection Agency, the Mexican SEMARNAT, and the binational International Boundary and Water Commission and Comision Internacional de Limits y Aguas on a binational project to improve water quality in the Lower Rio Grande/Rio Bravo below Falcon Dam to reduce salinity. 

Salinity in the Rio Grande/Rio Bravo 

The Lower Rio Grande/Rio Bravo (LRG/RB) is experiencing increasing salinity, which affects the millions of people living in the region who rely on the LRG/RB for consumption and irrigation, and many other uses. Increasing salinity in the LRG/RB is harmful to agricultural production, which is the major source of income on both the Mexican and the U.S. sides of the river. 

Students in previous LBJ School classes have developed a preliminary mass balance model of salinity in the LRG/RB based on: 

* provisional conductance data from the Texas Commission on Environmental Quality (TCEQ); 

* provisional flow data from the US Geological Survey (USGS), which works in conjunction with the IBWC from gages they monitor along the Rio Grande.  

Students in Fall 2022 collected from three locations both salinity and flow data, which were the locations used to complete the mass balance. The research team obtained rainfall data from multiple sources, which was not included in the mass balance, but could be used to further characterize the salinity problem in future studies. Using flow and salinity data, a salinity mass balance in the LRG/RB was completed in Excel. The mass balance indicates how much the salt load increased or decreased at a location in the LRG/RB relative to a location upstream.  

From the mass balance, it can be concluded that there are external sources that contribute to the increase or decrease in the salt load in the LRG/RB. While the salinity mass balance characterizes the problem of changing salt load in the LRG/RB, further analysis is required to determine what sources are contributing and how much of the change in salt load can be attributed to each source. The model is limited by the availability of data, including both in space and time, as well as by missing data. The model does not include rainfall, runoff events, groundwater, some tributary flows, or non-point salinity.  

This model serves as an initial foundation for a more developed salinity analysis. In Spring and Summer 2023 supplemental data were collected to model salinity and simulate proposed solutions.  

The purpose of the 2023-34 PRP is to conduct a thorough and robust salinity analysis in the LRG/RB and use the information to develop recommendations for Mexican, Texas and US agencies for improving water quality in the LRG/RB. This project will involve representative of multiple government agencies in the class and may be conducted in cooperation with Mexican government research staff and graduate students.

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