Santa Rosa, Texas, suffered an unfortunate landmark last year: its last sugar mill shut down after half a century, the victim of an ongoing and severe drought. The parched Rio Grande Valley watched a once-staple industry flicker out. Economists at Texas A&M had already forecast nearly a $1 billion hit to the region’s economy from 2023 irrigation shortages; by 2024, the mill’s gates were chained.
Yesterday, President Donald Trump waded into that longstanding frustration with a blunt, and understandable, threat: unless Mexico releases 200,000 acre-feet of Rio Grande water by December 31, the U.S. will impose an extra 5 percent tariff on Mexican imports—”IMMEDIATELY.” It’s classic Trump rhetoric, and it landed because the pain in South Texas is real. But here’s the twist: under the very same binational regime, Mexico is already propping up the American Southwest by conserving water in Lake Mead—a commitment that keeps the reservoir a couple of feet higher and delays painful cuts for U.S. cities and farms—and in 2024 Washington and Mexico added a new measure to conserve 400,000 acre-feet through 2026, roughly twice the one-off volume Trump is demanding on the Rio Grande.
Mexico is propping up Lake Mead even as Texas runs dry, and sinking trade with Trump tariffs won’t change that reality.
Common Knowledge
The 1944 Water Treaty obliges Mexico to deliver 1.75 million acre-feet to the U.S. from six Rio Grande tributaries over each five-year cycle; Trump says Mexico is behind and demands 200,000 acre-feet now or face tariffs.
On the right and among farmers, the mood is exasperation edged with fury. Texas Farm Bureau state director Brian Jones has called Mexico’s repeated shortfalls “infuriating,” warning that planted acres are down by as much as 45 percent in the Valley and that “we risk losing an entire industry” if nothing changes. “Something must be done and done now,” he said.
On the left—and among many economists—the alarm more generally is about the tool. Tariffs are, as Larry Summers has put it repeatedly this year, a “self-inflicted wound” that raise prices at home.
Diplomats warn of a different risk: linkage. Start tying water to tariffs (and migration, and fentanyl), says former Mexican ambassador Arturo Sarukhán, and “the danger is that all of the agenda… simply freezes.” In other words, smash the plumbing and you don’t get more water—you get fewer ways to solve anything.
Uncommon Knowledge
The treaty, crucially, has two ledgers. The one Trump has put loudly in the headlines is the Rio Grande: 1.75 million acre-feet per five-year cycle from Mexico to the U.S., designed that way because those Mexican tributaries are erratic. Mexico often catches up late, but Texas farmers hate the timing. Trump’s 200,000 acre-feet now-or-tariffs demand represents around 65 billion gallons.
The quieter ledger is the Colorado River: the U.S. owes Mexico 1.5 million acre-feet every single year, and when Lake Mead drops, both countries take shortage cuts under agreements called Minutes. Critically, Mexico can bank conserved water in Lake Mead—and has been doing so. Federal briefings note that Mexican conservation and storage have nudged Mead a couple of feet higher, buying time for American users tied to the reservoir’s shortage tiers. In April 2024, the two governments added Minute 330, under which Mexico will conserve an additional 400,000 acre-feet through 2026 to help prop up Mead—about double the one-time 200,000 Trump demands on the Rio Grande.
None of this excuses shortfalls that leave Texas orchards short; the Santa Rosa mill’s closure is not an abstraction. But it does show the relationship as a two-way system. Treat the Rio Grande dispute as a morality play and tariffs feel satisfying. See the Colorado ledger and the case for smashing trade to make a point looks shakier. The practical route is duller and more useful: use the treaty’s gear-work to make Rio Grande deliveries predictable (the International Water and Boundary Commission is already testing that with new steps to boost reliability and predictability), while keeping the Lake Mead bargain intact. The solution is likely plumbing, not tariffs.
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