What is an interstate compact?
An interstate compact is a formal agreement between two or more states. Under Article I, Section 10 of the Constitution, such agreements require the consent of Congress. Once approved, a compact functions as both state and federal law, binding the signatories to its terms. Compacts are commonly used for shared resources like rivers, transportation systems, and regional commissions.
The Rio Grande Compact
Signed in 1938 and ratified by Congress, the Rio Grande Compact allocates water from the 1,900-mile river among Colorado, New Mexico, and Texas. It sets delivery obligations from upstream states to downstream users and establishes a commission to oversee compliance. The river also flows into Mexico, which receives water under a separate 1906 treaty between the U.S. and Mexican governments.
How disputes get resolved
When states disagree over a compact, the U.S. Supreme Court has original jurisdiction — meaning the case is filed directly with the high court rather than working up through lower courts. The justices often appoint a 'special master' to gather evidence and recommend findings. In 2013, Texas sued New Mexico, alleging that groundwater pumping near the state line was reducing Rio Grande surface flows owed to Texas under the compact.
The federal role
Even when states negotiate among themselves, the federal government has interests at stake. The U.S. Bureau of Reclamation operates major dams and irrigation projects on the Rio Grande, and the State Department is responsible for treaty deliveries to Mexico. In the Rio Grande case, federal officials objected to a proposed settlement among the three states, arguing it could undermine the United States' ability to meet its international obligations.
The 2024 settlement
In 2024, the U.S. Supreme Court approved a settlement among Colorado, New Mexico, and Texas, ending more than a decade of litigation. The ruling allowed the states to resolve the dispute on their own terms, despite federal objections. Supporters viewed it as an affirmation of state authority over compact administration; critics warned it may leave unresolved questions about federal treaty compliance.
Drought as a backdrop
The legal questions play out against a worsening physical reality. The Rio Grande basin has been in a multi-decade drought, and Bureau of Reclamation data show reservoir storage at a fraction of historical averages. Similar pressures are reshaping disputes on the Colorado River and other Western waterways, where shrinking supplies force renewed negotiations over decades-old allocations.
The debate over control
Supporters of state primacy argue that states understand local hydrology, economies, and users best, and that compacts were designed to let states settle their own affairs with minimal federal interference. Supporters of a stronger federal role argue that rivers crossing international borders implicate national treaty duties and that federal agencies manage much of the infrastructure delivering the water. The Rio Grande case illustrates the tension between these views.
Why it matters to voters
How water is governed shapes farming, drinking supplies, tribal rights, energy production, and city growth across much of the country. As droughts intensify and populations shift, voters in river-basin states are increasingly asked to weigh in — directly or through their elected officials — on who should have the final say when state interests, federal authority, and international obligations collide.