S-4846-119
Read twice and referred to the Committee on Energy and Natural Resources.
Sponsored by Mark Kelly (D-AZ)
What it does
This bill would reauthorize the Transboundary Aquifer Assessment Program, a joint U.S.-Mexico scientific study of shared underground water supplies along the border. It would extend the program's funding authorization from fiscal years 2026 through 2036, add Arizona as an eligible state (alongside New Mexico and Texas), and reset the program's sunset date. One specific aquifer in the Yuma, Arizona groundwater basin would be excluded from the expanded coverage.
Who benefits
Residents of border communities in Arizona, New Mexico, and Texas who depend on shared groundwater for drinking water and agriculture. Farmers and ranchers in arid border regions who rely on aquifer data for water planning. State and local water managers who use the program's scientific data to make allocation decisions. Researchers and scientists at universities and federal agencies involved in the assessment work. Mexican border communities that benefit from shared data on jointly used aquifers.
Who is hurt
Taxpayers who would fund the program's reauthorization, though the specific appropriation amount is not specified in the bill text. The excluded Yuma groundwater basin aquifer area would not receive the same federal assessment resources as other covered aquifers. Competing federal programs that may face reduced appropriations if Congress funds this program within a constrained budget.
Supporters argue
Supporters argue that transboundary aquifers are a finite, shared resource that neither the U.S. nor Mexico can manage effectively without coordinated scientific data, and that the program has produced foundational hydrological assessments since its original authorization in 2006. They contend that adding Arizona — a state facing severe and well-documented water scarcity — is a straightforward recognition that border groundwater challenges extend beyond New Mexico and Texas, and that continued federal investment in data collection prevents costly disputes over water rights down the line.
Opponents argue
Opponents argue that water resource management is traditionally a state and local responsibility, and that a decade-long federal reauthorization may duplicate assessments already conducted by state agencies like the Arizona Department of Water Resources, which has managed the Yuma basin since 1984. They contend that without a specified appropriation amount or measurable performance benchmarks, the bill provides no accountability for how federal funds are spent over the 10-year period, and that the program's original authorization lapsed without a clear public accounting of its scientific outputs.
Constitutional context
Congress's authority to fund this program rests on the Commerce Clause (Art. I, §8, cl. 3) and the Necessary and Proper Clause (Art. I, §8, cl. 18), as groundwater shared across an international border affects interstate and foreign commerce. No significant constitutional tension is present; this is a narrow reauthorization of an existing cooperative scientific program, not a new regulatory mandate.
Checks and balances
Congress retains authority over appropriations, meaning the program can only operate if future Congresses actually fund it; the executive branch (through the U.S. Geological Survey and Bureau of Reclamation) implements the assessments, and the Tenth Amendment preserves state authority over water rights and allocation decisions.
Historical precedent
The original United States-Mexico Transboundary Aquifer Assessment Act (Public Law 109-448, 2006) authorized this same program for fiscal years 2007 through 2016, establishing the direct precedent for this reauthorization.