THIS IS NOT LEGAL ADVICE. This is a demo of how you can prepare research material using AI. Verify everything with a licensed attorney in your state.

Water Rights/Case Library

Dotted termshave plain-English definitions. Hover, or tap on a phone.

Tarrant Regional Water District v. Herrmann, 569 U.S. 614 (2013)

Why this matters: Texas tried to reach into Oklahoma and take water it said 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. entitled it to. The Supreme Court said 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. silence creates no cross-border right, 9 to 0. Read this next to Sporhase. Together they explain why a state’s power to keep water home is stronger than it first appears.

Doctrine: Interstate compacts, dormant Commerce Clausedormant Commerce ClauseA constitutional rule that stops states from unfairly blocking trade across state lines. It is why a state generally cannot just ban water from leaving., state sovereignty over water

Case name and citation

Tarrant Regional Water District v. Herrmann, 569 U.S. 614 (2013).

Court and year

Supreme Court of the United States. Decided June 13, 2013. Unanimous, 9 to 0. Opinion by Justice Sotomayor.

One-line holding

The Red River Compact creates no cross-border right for one signatory state to divert water located within another, so Oklahoma’s statutes restricting out-of-state water transfers are neither preempted by the Compact nor a violation of the Commerce Clause.

Facts

The Dallas-Fort Worth metroplex was growing fast and running short. The Tarrant Regional Water District, which supplies the area, went looking for water.

It found some in Oklahoma. Reach II, subbasin 5 of the Red River basin, just across the line.

The governing instrument is the Red River Compact, a congressionally sanctioned agreement allocating water among Oklahoma, Texas, Arkansas, and Louisiana. Section 5.05(b)(1) gives the states “equal rights” to subbasin 5’s water when flow reaches 3,000 cubic feet per secondcubic feet per secondA flow rate rather than a volume. 1 cubic foot per second running all day is about 2 acre-feet. or more, provided no state takes more than 25 percent of the water in excess of 3,000 cfscubic feet per secondA flow rate rather than a volume. 1 cubic foot per second running all day is about 2 acre-feet..

Tarrant applied to the Oklahoma Water Resources Board for permits to take water in Oklahoma and pipe it to Texas.

Oklahoma law effectively barred out-of-state transfers. Tarrant sued, arguing the Compact preempted those statutes and, alternatively, that they violated the dormant Commerce Clausedormant Commerce ClauseA constitutional rule that stops states from unfairly blocking trade across state lines. It is why a state generally cannot just ban water from leaving..

Tarrant’s textual argument rested on silence. Section 5.05(b)(1) says nothing about state lines. Tarrant read that silence to create a borderless common in subbasin 5, where any signatory could cross any boundary to reach a shared pool.

Oklahoma read the same silence in the opposite direction: no language granting cross-border rights means the drafters never intended to create any.

Does the Red River Compact’s silence about state borders create cross-border diversiondiversionMoving water out of the Great Lakes basin. The Compact bans new ones except in a few narrow cases. rights that preempt Oklahoma’s water export statutes, and do those statutes independently violate the Commerce Clause?

Holding and reasoning

Unanimous for Oklahoma. Tarrant loses on both grounds.

The Court framed the case precisely: “Unraveling the meaning of section 5.05(b)(1)‘s silence with respect to state lines is the key.”

Three considerations pointed the same way.

First, the background principle. “States rarely relinquish their sovereign powers, so when they do we would expect a clear indication of such devolution, not inscrutable silence.” Control over water within one’s own borders is a core state prerogative, and the Court would not infer its surrender from the absence of text.

Second, drafting practice. Many interstate compacts unambiguously permit signatory states to cross each other’s borders. The Red River Compact’s omission of such a provision “strongly suggests that the cross-border rights were never intended to be part of the States’ agreement.”

Third, the parties’ course of dealing, which had not reflected any assumption of cross-border access.

On the Commerce Clause, the Court held Oklahoma’s statutes did not offend it because the water at issue was already allocated by the Compact. It was not unallocated water moving in a free market.

Why it matters

Sporhase and Tarrant look like they point in opposite directions, and understanding why they don’t is worth the effort. See 1982-sporhase-v-nebraska.md.

Sporhase holds that water is an article of commerce and a state cannot discriminate against exports without a close fit to a legitimate purpose.

Tarrant holds that Oklahoma’s export restrictions survive, because water already allocated to a state by a congressionally approved compact isn’t in the stream of commerce the same way.

The reconciling principle is congressional consent. A state acting alone against interstate commerce is on thin ice. A state acting inside a compact Congress has approved is standing on federal law.

For a Great Lakes reader, that is the whole point. The Great Lakes Compact restricts diversionsdiversionMoving water out of the Great Lakes basin. The Compact bans new ones except in a few narrow cases., and Congress consented to it in Public Law 110-342 on October 3, 2008. Tarrant supplies the strongest recent evidence that this structure holds up: a unanimous Court, declining to read compact silence as a grant of cross-border access, and rejecting a Commerce Clause challenge to a state export restriction operating inside a compact framework.

The second lesson is about drafting. If a compact does not say a state may cross a border, assume it may not. Silence favors the status quo of state control.

Applied to the Great Lakes Compact, that reading is protective. The Compact bans new or increased diversions and carves narrow exceptions. Anyone arguing for a right the Compact does not expressly grant has to overcome Tarrant’s presumption.

What it means for a landowner today

No direct application to a specific Wisconsin parcel, and real significance for the framework around it.

Practical translation:

  • The legal defenses around Great Lakes water are more durable than they might appear. A unanimous Supreme Court has recently reinforced the underlying principles.
  • A thirsty distant metro cannot simply buy its way to Great Lakes water. It would need an exception under the Compact, which requires the approval of the Compact Council, and the Waukesha application in 2016 showed how demanding that process is even for a straddling-county community immediately adjacent to the basin.
  • The realistic pressure on your water remains in-basin: municipal growth, agriculture, industrial and data center demand, and groundwater drawdowndrawdownHow far the water level drops while a pump is running.. Those are not diversion questions.

What to verify for a specific parcel: whether it is inside the basin, the long-term supply plan of the utility serving it, and local groundwater conditions. Who verifies: the Wisconsin DNR, the municipal water utility, and a hydrogeologisthydrogeologistA geologist who specializes in groundwater. Worth hiring for acreage, tricky geology, or any large planned withdrawal..

See ../03-wisconsin-great-lakes/ for the Compact’s mechanics.

Subsequent history / is it still good law

Good law as of July 2026. Tarrant has not been questioned and is regularly cited for both the compact interpretation principle and the reluctance to infer surrender of state sovereign powers.

The Court applied similar reasoning about compact structure and federal interests in Texas v. New Mexico and Colorado (2024), though on a different question. See 2024-texas-v-new-mexico-and-colorado.md.

Tarrant Regional Water District pursued other supply options after losing, including projects within Texas.

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.