Why It Matters
A federal lawsuit is challenging Idaho’s authority to curtail water use at Idaho National Laboratory and administer federal water rights. The case could affect how other decreed water rights are handled in coalition delivery call proceedings, according to state attorneys.
What Happened
The federal government sued the state of Idaho, the Idaho Department of Water Resources and department Director Mathew Weaver in U.S. District Court on Sept. 11.
The lawsuit seeks to stop Idaho from enforcing a water curtailment order at the laboratory and to prevent state officials from administering federal water rights. Federal officials argue that federal supremacy protects federal installations from direct state regulation.
Weaver issued the curtailment order in May. It applies to water rights established after Oct. 11, 1900. Curtailment means water use is shut off completely.
Idaho denied the federal allegations and filed a countersuit Oct. 16. Attorney General Raúl Labrador said federal agencies should comply with the same water laws that apply to other Idaho water users.
“Water is the lifeblood of Idaho, and my office will protect the water rights of Idahoans who depend on it,” Labrador said.
By the Numbers
- 35,000 acre-feet: Annual water right held by the U.S. Department of Energy in Idaho.
- 890 square miles: Size of the Idaho National Laboratory complex.
- Sept. 11: Date the federal lawsuit was filed.
- Oct. 16: Date Idaho submitted its response and countersuit.
- 2026 water year: Period during which the Energy Department joined the Big Lost River Ground Water District.
Zoom Out
The Energy Department joined the Big Lost River Ground Water District for the 2026 water year. The lawsuit also challenges Idaho’s authority to enforce water rights connected to the federal laboratory.
Idaho is a finalist to host a new U.S. Department of Energy Nuclear Lifecycle Innovation Campus. The laboratory’s water-rights dispute comes after a 2024 state water settlement agreement.
What’s Next
The case may proceed in federal or state court. State attorneys said the dispute could affect administration of every other decreed water right involved in coalition delivery call proceedings.
The governor’s office said Gov. Brad Little has continued defending Idaho’s water sovereignty.
About the Author
