This bill is about making sure Mexico delivers water to the United States as promised under a 1944 treaty. The treaty covers water from the Colorado River, Tijuana River, and Rio Grande, and Mexico is supposed to provide at least 350,000 acre-feet of water per year to the U.S.

Here's what the bill does: The Secretary of State must report to Congress every year on whether Mexico is meeting its water delivery obligations. If Mexico fails to deliver the required amount of water, the President must deny any special emergency water requests Mexico makes to the U.S. The President can also limit or reduce cooperation with Mexico on economic sectors that depend on water—like agriculture or irrigation—though the bill carves out an exception for efforts to stop drug trafficking like fentanyl.

There's one loophole: Mexico can still get emergency water if the Secretary of State certifies to Congress that it's needed for a genuine ecological, environmental, or humanitarian crisis and won't be used for regular city water supplies, industry, or normal needs. This certification has to be renewed every 120 days. Essentially, the bill uses water as leverage to pressure Mexico to live up to its treaty obligations, while still allowing for genuine emergencies.