U.S. President Donald Trump has warned Mexico that his administration is prepared to impose new tariffs if the country does not release water owed to the United States under a decades-old treaty. The threat comes amid growing pressure from lawmakers and agricultural groups in Texas, who say shortages are damaging farms and livestock operations.
In a post on Truth Social on Monday, Trump accused Mexico of withholding water that U.S. agriculture relies on.
“Mexico is not responding, and it is very unfair to our U.S. Farmers who deserve this much needed water,” Trump wrote, adding that he has authorized documentation to impose a 5% tariff if Mexico does not comply “immediately.”
At the center of the dispute is the 1944 Utilization of Waters Treaty governing the Colorado River, the Tijuana River and the Rio Grande. Under the agreement, Mexico must supply the United States with an annual average of at least 350,000 acre-feet of water from Rio Grande tributaries. U.S. officials have long argued that Mexico regularly falls short of that requirement.
According to the International Boundary and Water Commission, Mexico has underdelivered by roughly 73,000 acre-feet over the past five years. The treaty requires Mexico to compensate for shortfalls in subsequent years, unless both governments determine that an undefined “extraordinary drought” applies — a clause now complicating enforcement.
Texas is currently experiencing drought conditions, and state lawmakers say the shortfall is directly impacting production. U.S. Representative Jodey Arrington previously told a House committee that insufficient water deliveries have caused an estimated $1 billion in losses for irrigated crops in Texas.
This is not the first time Trump has threatened retaliatory measures. In April, he issued a similar warning, raising the possibility of sanctions or tariffs if Mexico did not increase water deliveries.
If implemented, the proposed tariffs would add 5% to Mexican imports — raising the effective rate to 30%. However, much of Mexico’s trade is exempt under the United States–Mexico–Canada Agreement (USMCA), meaning the impact of new tariffs remains uncertain.
The trade pact faces a scheduled review in July, and Trump has signaled he may allow the agreement to lapse if his administration concludes it does not sufficiently benefit U.S. economic interests.
Mexico has not yet issued a public response to the latest threat.
