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Water Rights/Case Library

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Texas v. New Mexico and Colorado, 602 U.S. 943 (2024)

Why this matters: Three states negotiated a settlement of a Rio Grande dispute, and the Supreme Court threw it out because the federal government objected. If you want to know whether a state can quietly trade away water in a compactcompactA binding agreement between states that Congress approves. Once approved it becomes federal law and overrides conflicting state rules. The Great Lakes Compact is one. basin, the answer is no when the United States has its own claim. Directly relevant to how the Great Lakes CompactcompactA binding agreement between states that Congress approves. Once approved it becomes federal law and overrides conflicting state rules. The Great Lakes Compact is one. holds.

Doctrine: Interstate compacts, equitable apportionmentequitable apportionmentThe US Supreme Court dividing an interstate river between states that cannot agree. The evidence bar is very high. Florida spent over a decade and lost., federal interests

Case name and citation

Texas v. New Mexico and Colorado, 602 U.S. 943 (2024). No. 141, Original (docketed as No. 22O141).

Court and year

Supreme Court of the United States, original jurisdiction. Decided June 21, 2024. 5 to 4. Opinion by Justice Jackson, joined by Chief Justice Roberts and Justices Sotomayor, Kagan, and Kavanaugh. Gorsuch dissented, joined by Thomas, Alito, and Barrett.

One-line holding

Texas, New Mexico, and Colorado could not enter a consent decreedecreeThe court order at the end of an adjudication, spelling out exactly who gets how much water and in what order. resolving the Rio Grande Compact litigation, because the decreedecreeThe court order at the end of an adjudication, spelling out exactly who gets how much water and in what order. would dispose of the United States’ distinct Compact claims without its consent.

Facts

The Rio Grande Compact of 1938 divides the river among Colorado, New Mexico, and Texas. It has an unusual delivery point: New Mexico’s obligation is measured at Elephant Butte Reservoir, well north of the Texas line.

Water released from Elephant Butte travels roughly 100 miles through New Mexico before reaching Texas. The federal Rio Grande Project, operated by the Bureau of Reclamation, delivers that water to irrigation districts in both states and to Mexico under a 1906 treaty.

Texas filed an original action in January 2013, claiming that groundwater pumping in southern New Mexico below Elephant Butte was intercepting water bound for Texas and shorting its Compact share.

In 2018 the Court allowed the United States to intervene and pursue its own Compact claims, recognizing that federal interests in the Rio Grande Project and the Mexico treaty were distinct.

After a partial trial and months of negotiation, Texas and New Mexico reached a settlement in 2022 and moved for entry of a proposed consent decree that would codify an accounting method for allocating the river.

The United States objected. The decree would have cut off the federal claim that New Mexican groundwater pumping violated the Compact.

Special Master Michael Melloy recommended approval anyway. The United States filed an exception.

May states settle original-jurisdiction compact litigation through a consent decree that resolves claims the United States has separately asserted and continues to press?

Holding and reasoning

No. Exception sustained, motion to enter the consent decree denied.

The Court applied an ordinary settlement principle: “parties who choose to resolve litigation through settlement may not dispose of the claims of a third party,” quoting Firefighters v. Cleveland, 478 U.S. 501, 529 (1986).

The United States was not a bystander. In 2018 the Court had permitted it to intervene precisely because it holds unique federal interests, and in 2024 it was still advancing the same claims backed by the same interests.

The proposed decree would have settled all parties’ Compact claims and, in doing so, extinguished the federal request for relief on New Mexican groundwater pumping. Precedent does not allow that.

Gorsuch’s dissent argued the majority gave the federal government an effective veto over interstate compact settlements, elevating the United States above the sovereign states whose compact it is. He warned this would make these disputes harder to resolve.

Why it matters

Compacts look like contracts between states. This case shows they are not only that.

When the United States has built the infrastructure, signed a treaty with Mexico, and asserted its own claims, it becomes a party with standing to block a deal it doesn’t like. Two states cannot shake hands across the third party’s interest.

The practical effect was another 2 years of litigation and a renegotiation that included the federal government. That renegotiation worked. See the subsequent history below, which is the more interesting half of this story.

For a Great Lakes reader, the transferable point is about the durability of compact obligations. The Great Lakes Compact received congressional consent in 2008, which converts it into federal law. A compact that is federal law is not something 2 member states can renegotiate privately, and it is not something a single state legislature can amend on its own.

Compare Tarrant Regional Water District v. Herrmann, where Texas learned that a compact gives you only what its text says. See 2013-tarrant-v-herrmann.md. Together the 2 cases describe the shape of compact law: the text controls, and the federal government’s seat at the table is real.

The groundwater fact pattern deserves a note. Texas’s entire theory was that pumping wells in New Mexico depleted surface water owed to Texas. Nobody in 2024 disputed that groundwater and surface water are connected. That premise took a century to become uncontroversial, and Wisconsin’s own version of it runs through Lake Beulah. See 2011-lake-beulah-v-dnr.md.

What it means for a landowner today

No direct application to a Wisconsin parcel.

The useful takeaways:

  • Compacts with congressional consent are sturdy. The Great Lakes Compact’s protections against diversiondiversionMoving water out of the Great Lakes basin. The Compact bans new ones except in a few narrow cases. are federal law, and dismantling them would take an act of Congress rather than a state-level deal. That is the structural reason a Great Lakes parcel sits behind a real legal wall.
  • Groundwater pumping that depletes surface water is now a recognized legal injury at every level, including between sovereign states. The same physics governs a high capacity wellhigh capacity wellIn Wisconsin, a well (or all wells on 1 property combined) capable of pumping 100,000 gallons a day or more. These need DNR approval. An ordinary house well does not. next to your lake.
  • Interstate water disputes take more than a decade and often end in negotiated settlement rather than judicial victory. Texas filed in 2013 and got a final decree in 2026.

Subsequent history / is it still good law

The 2024 holding is good law as of July 2026 on its legal point: states cannot settle away federal Compact claims without federal consent.

The litigation itself is over, and the ending is worth recording precisely.

After the 2024 decision, Judge D. Brooks Smith was appointed successor Special Master and ordered the 3 states and the United States back into mediation. On August 29, 2025, the states filed a joint motion for a refashioned decree, this time with no objection from the United States.

Special Master Smith recommended entry in his Fourth Interim Report, filed February 2026. No party filed exceptions.

On May 26, 2026, the Supreme Court entered the final decree and discharged the Special Master, ending more than 13 years of litigation. On June 8, 2026, the United States’ claims were dismissed with prejudice.

The decree establishes a new accounting framework for Rio Grande deliveries and requires New Mexico to reduce annual groundwater depletions by 18,200 acre-feetacre-footEnough water to cover 1 acre a foot deep: 325,851 gallons. Roughly what 2 or 3 suburban households use in a year. within 10 years, with half of that reduction within 5 years. Implementation is expected to involve retiring water rights on irrigated farmland in southern New Mexico, irrigation efficiency work, and stormwater capture.

Read the sequence as a whole. The 2024 rejection forced a settlement that actually included every party with a claim, and that settlement held.

Sources

Research demo, not legal advice. Facts current as of July 2026. Water law is state-specific and moves quickly, so confirm anything you plan to act on with a licensed attorney and the relevant state agency.