Colorado has accused neighboring Nebraska of stealing its water amid an escalating Supreme Court fight that relates to a nearly century-old agreement governing the South Platte River Compact. "We will defend the rights of Colorado water users, which is why we are asserting our own claims against Nebraska for using water that belongs to Colorado under the compact," Attorney General Phil Weiser said in a release this week, adding: "If anything, Nebraska owes Colorado for the water that the Cornhusker State has wrongfully taken." Weiser had no further comment when approached by Newsweek. Newsweek also reached out to Nebraska attorney general Mike Hilgers via email for comment.
The dispute comes as competition for water is intensifying across the American West, where prolonged drought, population growth and climate pressures have placed increasing strain on rivers governed by decades-old interstate agreements. At the heart of the fight between the two states is who gets to use water from the South Platte river, a resource that is increasingly valuable in the drought-prone West. In 1923 Colorado and Nebraska signed the South Platte River Compact, setting out each state's rights to water from the river.
The agreement was later approved by Congress in 1926. The current argument dates back to 2021 when Nebraska revived plans for the Perkins County Canal. It argues the project is needed to secure water the state is entitled to under the compact, and has raised concerns that Colorado's water use was reducing Nebraska’s supply.
In July 2025, Nebraska sued Colorado in the Supreme Court, alleging that Colorado has failed to deliver water required under the South Platte River compact and has improperly interfered with Nebraska's efforts to develop the Perkins County Canal, a project Nebraska says is necessary to secure water supplies for future generations. In June this year the Supreme Court agreed to allow Nebraska’s complaint to proceed. Colorado responded on Monday with a 58-page counterclaims filing that argues Nebraska, not Colorado, is violating the compact through excessive groundwater pumping that causes reduced flows into Colorado.
The dispute rages on as both states continue to grapple with drought conditions and many face an expected increase in water bills. Drought Monitor, large portions of Colorado and Nebraska remain in drought, with parts of both states experiencing extreme or exceptional drought as of September 2026. Colorado is seeking dismissal of one portion of Nebraska's lawsuit, arguing Nebraska has no legal basis for its claim that Colorado's water administration system is unlawfully complex.
Colorado argues the compact says nothing about requiring a "simple" or "self-executing" system. The state also questions the value of Nebraska's proposed Perkins County Canal, arguing the project poses "significant technical and financial risks" and may ultimately yield too little water to justify the investment. Colorado further argues that Nebraska does not have a right to a fixed amount of water flowing across the state line.
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