Texas has unilaterally taken control of nine islands on the Rio Grande, prompting Mexico to demand respect for the 1970 Boundary Treaty. State Land Commissioner Dawn Buckingham authorised the Texas National Guard to access the river islands to maintain operational security.
The Mexican government responded by asserting that the binational International Boundary and Water Commission (IBWC) holds sole authority to determine the international boundary under the 1970 treaty. It said any work on the islands requires consideration and approval by both the US and Mexican sections of the commission.
Mexico’s Foreign Ministry said the 1970 Boundary Treaty between Mexico and the United States established the border along the middle of the Rio Grande’s normal channel, and that island ownership can vary due to natural shifts in the watercourse. The ministry said the IBWC alone can determine whether islands or the river channel have shifted due to natural conditions and whether that constitutes a change to the boundary.
Buckingham’s October 26 letter to Major General Thomas Suelzer and Colonel Freeman Martin describes the decision, stating it follows a request from US Customs and Border Protection regarding 28 islands previously considered unclaimed or of undetermined ownership. “This effort builds on the GLO’s work to establish ownership of Rio Grande islands and ensure law enforcement can access state-owned property,” an excerpt of the letter reads. The GLO said title to the islands had not been definitively established, creating uncertainty about state, federal or Mexican ownership and hampering law enforcement access.
Rosario Sánchez, director of the binational nonprofit Binational Waters, said decisions on federal boundaries are not a state matter, reiterating the IBWC’s exclusive role in determining whether natural conditions have shifted the islands or river channel and whether that constitutes a boundary change.
Gabriel Eckstein, a water law scholar at Texas A&M University and president of the International Water Law Association, questioned what the claim means. He said the real question is whether Texas is claiming U.S. islands and whether they belong to the federal government or the state. “Texas contends that these islands are being used by cartels, which complicates the situation, because it is trying to assert its authority over concerns related to illegal immigration and drug trafficking,” Eckstein said by video call. Eckstein said Texas’s claim that the islands had no owner was incorrect, since the boundary and title had already been established by international treaties.
In 2023, the GLO declared Fronton Island, a 170-acre parcel in Starr County, to be state land. The Texas Department of Public Safety and National Guard then removed vegetation on the island during operation Flat Top, which helped disrupt criminal activity there. The IBWC has the decision on its agenda for now.
Analysis
Why This Matters
- Texas is asserting unilateral state control over an international border area, challenging a federal treaty and the authority of the binational commission created to manage it.
- The move could set a precedent for state governments taking independent action on international boundaries, escalating tensions with Mexico and within US federalism.
- The dispute tests whether international water treaties can withstand unilateral national security claims made by a state government.
Background
The 1970 Boundary Treaty between the US and Mexico was designed to resolve border disputes and regulate changes in the Rio Grande. The International Boundary and Water Commission (IBWC) is the binational body responsible for administering the treaty and determining the exact boundary line. Texas has taken an increasingly assertive role in southern border security under the current administration.
Key Perspectives
- Texas General Land Office: Argues the islands lacked definitively established ownership, hampering law enforcement, and cites the need to prevent border islands from being exploited by cartels and smugglers.
- Mexican Government: States the 1970 treaty reserves boundary determinations to the IBWC, and any unilateral actions on the islands require prior binational approval.
- Gabriel Eckstein (Texas A&M University): Contends the claim is less about taking Mexican land and more about whether the islands are state or federal US property, noting the boundary was already settled under international law.
- Rosario Sánchez (Binational Waters): Holds that decisions about federal boundaries are not a state matter and must be left to the IBWC.
What to Watch
- Whether the IBWC formally objects to Texas’s actions or attempts to open a diplomatic channel.
- Potential legal challenges from the US federal government or Mexico over state versus federal authority over the border.
- Whether Texas extends its claim to the remaining 19 islands referenced in the CBP request.
Checked
12 claims in this story checked against 1 source: 10 supported.
Show each claim
- SupportedBuckingham’s letter says, “This effort builds on the GLO’s work to establish ownership of Rio Grande islands and ensure law enforcement can access state-owned property.”El País English: ““this effort builds on the GLO’s work to establish ownership of Rio Grande islands and ensure law enforcement can access state-owned property.””
- SupportedEckstein said, “Texas contends that these islands are being used by cartels, which complicates the situation, because it is trying to assert its authority over concerns related to illegal immigration and drug trafficking.”El País English: ““Texas contends that these islands are being used by cartels, which complicates the situation, because it is trying to assert its authority over concerns related to illegal immigration and drug trafficking,” Eckstein said by video call.”
- SupportedTexas seized nine islands on the Rio Grande.El País English: “Mexico urges respect for treaties after Texas seizes nine islands on Rio Grande.”
- Partly supportedMexico demanded Treaty compliance.El País English: “The Mexican government has responded by asking that the 1970 Boundary Treaty between the two countries be respected”
- Partly supportedTexas unilaterally took control of nine islands on the Rio Grande.El País English: “acting unilaterally, the Texas government has announced it has taken control of nine islands located in the water border between Mexico and the United States”
- SupportedBuckingham authorised the Texas National Guard to access the islands to maintain operational security of the southern border.El País English: “Dawn Buckingham, that state’s land commissioner, authorized the Texas National Guard to access those small river islands in order to maintain the operational security of the southern border.”
- SupportedMexico says the IBWC has sole responsibility for determining the international boundary.El País English: “The Mexican government has responded by asking that the 1970 Boundary Treaty between the two countries be respected and says that determination of the international boundary is the sole responsibility of the International Boundary and Water Commission.”
- SupportedMexico’s Foreign Ministry said work on the islands requires consideration and approval by both sections of the IBWC.El País English: ““Accordingly, any work or action intended to be carried out on these islands requires consideration and approval by both sections of that Commission in accordance with Article IV of the Treaty,” the ministry said.”
- SupportedThe treaty puts the border along the middle of the Rio Grande’s normal channel, and island ownership can vary with natural shifts in the channel.El País English: “the 1970 Boundary Treaty between Mexico and the United States establishes that the border follows the middle of the river’s normal channel. Therefore, island ownership can vary due to natural shifts in the channel”
- SupportedThe IBWC alone can determine whether natural conditions shifted islands or the channel and whether that changed the boundary.El País English: “She reiterates that the IBWC is the only body that can decide whether islands or the river channel have shifted due to natural conditions such as erosion, sedimentation or flooding, and whether that constitutes a change to the boundary.”
- SupportedBuckingham’s October 26 letter followed a CBP request about 28 islands previously considered unclaimed or of undetermined ownership.El País English: “The letter says that after receiving a request from U.S. Customs and Border Protection regarding 28 islands in the Rio Grande that had previously been considered unclaimed or of undetermined ownership”
- SupportedThe GLO said the islands’ title had not been definitively established, creating uncertainty about whether they belonged to Texas, the federal government or Mexico and hampering law-enforcement access.El País English: ““For years, title to these islands had not been definitively established, creating uncertainty about whether they belonged to the state of Texas or the federal government or Mexico, and hampering access by state law enforcement and border security operations,” the agency replied”