Facing water shortages, states struggle with competing impulses, desiring to restrict water exports to other states while simultaneously importing water from neighboring jurisdictions. In 1982, the Supreme Court weighed in on this issue through its seminal decision, Sporhase v. Nebraska ex rel. Douglas. Determining that groundwater is an article of commerce, the Court held invalid under the dormant Commerce Clause a provision of a Nebraska statute limiting water export. The issue has again come into the national spotlight, as the Tarrant Regional Water District of Texas has challenged Oklahoma legislation limiting water exports, and as Wind River L.L C of Nevada has contested the denial of its application for a permit to acquire water from Arizona.

This Article examines the dormant Commerce Clause as it applies to water export. It argues that Sporhase asked the wrong question, transplanting a relevant issue from the context of the affirmative Commerce Clause — whether water is an article of commerce — into the context of the Clause's dormant aspect. Observing that the U.S. Supreme Court has not addressed the issue of water export regulation directly for more than twenty-five years, this paper suggests three ways in which the Court can bring its water cases into doctrinal harmony with its modern dormant Commerce Clause jurisprudence. In so doing, this Article develops a new analytical paradigm, the "water continuum," that respects the nuances of state water law and recognizes that not all water has the same constitutional status.