Former US President Donald Trump has issued a fresh warning to Mexico, threatening to impose a 5 percent tariff on Mexican imports over what he describes as repeated delays in fulfilling water-sharing obligations under the 1944 US–Mexico Water Treaty. In a post on his social media platform Truth Social, Trump said Mexico must release 200,000 acre-feet of water from the Rio Grande by December 31 to partially compensate for more than 800,000 acre-feet of water it allegedly owes to the United States.
The 1944 treaty governs how water from the Rio Grande and the Colorado River is shared between the two countries. Under the agreement, Mexico is required to deliver a fixed quantity of water from its tributaries to the United States in five-year cycles. The current cycle has seen repeated shortfalls, largely due to prolonged drought conditions and growing agricultural water demand in northern Mexico. However, US officials and border-state lawmakers have increasingly accused Mexico of failing to manage its water resources efficiently.
Trump, who has made border security and trade enforcement central themes of his political messaging, said the water delays were severely harming farmers in Texas, who rely heavily on Rio Grande water for irrigation. He described the situation as deeply unfair and warned that economic pressure in the form of tariffs could follow if Mexico does not act swiftly. The tariff threat mirrors the aggressive trade tactics he used during his presidency, including duties on steel, aluminum and Chinese goods.
Texas farmers and agricultural lobby groups have long raised concerns about falling reservoir levels and reduced water deliveries, arguing that the shortfall threatens crop production and rural livelihoods. Several Texas lawmakers have also urged Washington to pursue stronger diplomatic and economic measures to compel Mexico to meet its commitments. Reservoirs such as Lake Amistad and Falcon Lake have recorded historically low water levels in recent years, intensifying these concerns.
On the Mexican side, authorities have maintained that severe drought conditions linked to climate change have significantly reduced water availability. They have argued that domestic water needs for farms and urban populations must also be balanced alongside international treaty obligations. Mexican officials have previously sought diplomatic extensions and negotiated temporary adjustments to avoid escalating tensions.
The new tariff warning, however, risks reopening trade friction between the two countries, whose economies are deeply interconnected through supply chains, manufacturing and agriculture. Mexico is one of the United States’ largest trading partners, and even a modest tariff could disrupt cross-border commerce, raise consumer prices, and affect industries ranging from automotive manufacturing to food exports.
Diplomatic analysts warn that trade penalties tied to water disputes could complicate broader bilateral cooperation on issues such as migration, energy, and security. With climate change expected to increase water stress across North America, experts also caution that similar treaty disputes could become more frequent unless long-term joint water management strategies are implemented.
As of now, there has been no official response from the Mexican government to Trump’s latest statement. US federal agencies continue to monitor reservoir levels and treaty compliance as diplomatic channels remain open. Whether the tariff threat will translate into actual trade action remains uncertain, but it has once again brought the critical issue of cross-border water sharing into sharp public and political focus.
