TAAP Act Expands Shared US-Mexico Water Assessments to Arizona, Authorizes $1.5M Annually Through 2033

The Transboundary Aquifer Assessment Program Act, or TAAP Act, is essentially a check-up bill for critical underground water resources shared between the US and Mexico. If you live in the Southwest, this is a big deal, because this legislation reauthorizes and updates a key program designed to figure out how much water is down there and how fast we’re using it.

Why We’re Talking About Underground Water

This bill focuses on transboundary aquifers—massive underground water systems that don't respect international borders. For the millions of people and huge agricultural industries relying on these resources in the border states, knowing the health of these aquifers is crucial for long-term planning and stability. The original program was set up to assess these shared resources, but this update makes three key changes.

First, the TAAP Act officially expands the program's geographic reach to include Arizona (SEC. 2). Previously, the assessment work was primarily focused on Texas and New Mexico. Given the intense water needs and shared aquifers in Arizona, this change closes a significant gap. For a farmer or a city planner in Tucson, this means the federal government will now be directly involved in gathering the data needed to manage their shared water supply with Mexico, which is a major step toward better regional resource management.

The Money and the Timeline

The second major change involves the funding structure. The bill authorizes $1,500,000 for each fiscal year, running from 2026 through 2033 (SEC. 2). This essentially guarantees that the program has an authorized budget to operate for the next eight years. While this sounds straightforward, it’s worth noting that the previous authorization was $50 million spread over 10 years (averaging $5 million annually). The new, lower annual authorization of $1.5 million might mean the program has to be more strategic about its assessment work, which could pose a practical challenge in covering the expanded territory that now includes Arizona.

The third, and most technical, change is how the program’s authority is set to expire. The bill updates the sunset clause so that the program’s authority ends when the new TAAP Act is enacted, effectively replacing the old expiration date tied to the original law (SEC. 2). This is standard legislative housekeeping that ensures the program doesn't accidentally sunset prematurely under the old rules.

In short, the TAAP Act is an important piece of maintenance legislation that ensures the continued scientific assessment of a critical, shared resource. It brings Arizona into the fold and locks in funding authorization for nearly a decade, providing necessary stability for water management planning in the US Southwest.