United States Solicitor General Argues the Supreme Court Should Rule on Nebraska v. Colorado Water Rights Case

The United States Solicitor General recently moved the dispute between Colorado and Nebraska over water forward in a significant way. Specifically, the Solicitor General asked the Supreme Court to grant Nebraska leave to file its water rights action against Colorado. That recommendation substantially increases the likelihood that the Court will accept the case and appoint a special master to examine Nebraska’s claim that Colorado deprived Nebraska of water during the irrigation season.

The United States Constitution grants the United States Supreme Court original jurisdiction over suits between states. In July 2025, Nebraska requested leave from the Supreme Court to file an original action against Colorado over water rights.

Nebraska sought to enforce the 1923 South Platte River Compact to protect its asserted right to construct the Perkins County Canal in western Nebraska and eastern Colorado. The bill of complaint cited three Articles of the Compact in its challenge against Colorado:

• Article IV. Nebraska has priority over lower-section Colorado users to 120 cubic feet per second (cfs) of the river’s water during irrigation season (April 1 to October 15).
• Article VI. Nebraska obtains a right to 500 cfs of the South Platte’s water during the non-irrigation season (the rest of the year) contingent on the construction of the Perkins County Canal. The Canal is a long-contemplated project for which the Nebraska Legislature recently allocated more than $600 million in funding.
• Article VIII. Colorado must enforce the Compact without the need for additional legislation from the Colorado legislature. The Article does not state how Colorado must implement specific compliance measures.

Nebraska alleged Colorado used augmentation plans that encourage groundwater pumping and expanded irrigated acreage in the Lower Section. Nebraska claimed the plans will reduce streamflow and prevent Nebraska from receiving its 120 cfs irrigation-season entitlement under Article IV and could affect disputes related to Nebraska’s potential canal rights. Nebraska also claimed the augmentation plans are too complex and prevent effective enforcement of the Compact under Article VIII.

Colorado responded and generally denied the claims. It urged the Supreme Court to deny Nebraska leave to file the action.

As is typical, the Supreme Court invited input from the Solicitor General. On May 20, 2026, the Solicitor General filed a response that agreed, in part, with Nebraska’s position.

The Solicitor General argued Article IV presents a suitable claim that one State deprived another of water to which it is entitled under an interstate compact. The Solicitor General asserted Article IV depends on factual questions and asked the Supreme Court to refer that claim to a special master. A special master is an independent officer the Supreme Court appoints in original jurisdiction cases to conduct factfinding and make recommendations to the Court.

The Solicitor General argued Nebraska’s other claims, however, fail to present a justiciable case or controversy or face other threshold barriers. For instance, Nebraska identified no actual obstruction, such as a permit denial or a physical barrier to construction. 

Nebraska cited statements made by Colorado officials in its Article VI claims such as calling the canal a “boondoggle” and that the canal would “raise some significant legal issues.” The Solicitor General claimed Nebraska does not explain how those statements injure it or violate the Compact.

The Supreme Court has not yet acted on the Solicitor General’s recommendation. It will likely decide whether to accept the case and appoint a special master. The Solicitor General’s brief clarifies the issues likely to shape the Court’s decision in coming months and the scope of any subsequent proceedings before a special master should the case proceed. If the Court appoints a special master, affected water users in both states may face discovery obligations and may want to participate in proceedings that could shape water rights along the South Platte for decades to come.

Baird Holm’s environmental and natural resources team regularly advises landowners, water districts, developers, and utilities on water rights, interstate compact issues, and related permitting and environmental compliance matters throughout the Midwest. If you have questions about how this case may affect your operations or water rights, please contact us.

David C. Levy
Hannes D. Zetzsche
Jackson R. Langin, Summer Associate