Skip to main content
U.S. flag

An official website of the United States government

Statement of the U.S. Geological Survey, Department of the Interior

October 25, 2023

before the House Committee on Natural Resources, Subcommittee on Water, Wildlife, and Fisheries, on H.R. 5874 TAAP Act

Chairman Bentz and Ranking Member Huffman, thank you for this opportunity to provide the views of the U.S. Geological Survey (USGS) on H.R. 5874, the Transboundary Aquifer Assessment Program Act, or TAAP Act. The TAAP was first authorized by Congress in 2006 and is implemented by the International Boundary and Water Commission – Mexico Section; the USGS and its Water Resources Research Institutes located at the University of Arizona, New Mexico State University, and Texas A&M; and the Comisión Nacional del Agua or CONAGUA.



In the original authorization, certain aquifers which underly the U.S.-Mexico border are designated as priorities for the TAAP, namely the Hueco Bolson and the Mesilla aquifers underlying New Mexico, Texas, and Chihuahua, and the Santa Cruz River Valley and San Pedro aquifers underlying Arizona and Sonora. In the Mesilla basin, the USGS and its partners are conducting field studies to establish the aquifer’s physical characteristics, geochemistry, and recharge along the Rio Grande. This work will support a binational technical working group that is discussing a framework for a model of the basin. Such a model has been developed for the Santa Cruz River Valley and San Pedro basins, and discussions are underway to update the existing model for the Hueco Bolson basin.

Map of current TAAP priority aquifers. Map Area of lower United States and northern Mexico.
Maps of current TAAP priority aquifers, courtesy Univ. of Arizona.

In the time since the original authorization of the TAAP, additional water-use and development along the U.S.-Mexico border in Arizona and Sonora has highlighted the value of collaborative aquifer investigations. For example, current cooperation on the ecologically and culturally sensitive Quitobaquito Hills and La Abra Plain aquifers is identifying areas of needed investigation. Discussions among the TAAP partners suggest support for designating them as priorities.


H.R. 5874, TAAP Act

Under the TAAP, the Secretary currently has the authority to designate additional aquifers under New Mexico and Texas as priorities. Sec. 2 of H.R. 5874 extends this authority to Arizona, with the exception of the Yuma basin. This section also extends the sunset for the TAAP to 2035.

Reauthorization of the TAAP is important to the ongoing work of the USGS and its partners. Given discussions with those partners, the USGS supports the expansion of authority to designate priority TAAP aquifers in Arizona.