LINCOLN, Neb. (DTN) -- The U.S. Supreme Court on Monday agreed to hear a water dispute between Nebraska and Colorado that involves allegations from Nebraska officials of illegal water diversions and obstructions by Colorado officials on efforts to build a canal.

The high court granted Nebraska leave to file a bill of complaint. Once that's done, Colorado will have 30 days to respond, according to the court's order.

The Supreme Court has jurisdiction in disputes between states, and Nebraska said in its original complaint that the court's intervention is needed to stop Colorado from violating the South Platte River Compact, in effect since 1923.

The Perkins County Canal project dates to a drought in the 1890s when desperate western Nebraska farm families started digging out a canal from the South Platte River in Colorado with plans to irrigate their crops.

The canal needed to go about 65 miles, but the project was scrapped in 1895 after about 16 miles were dug out, according to a historical article on the project in the North Platte Telegraph. In 1923, though, Nebraska leaders made sure to insert a clause in their water compact with Colorado to keep open the option for a canal.

In May 2026, the U.S. government filed a brief with the Supreme Court in the case recommending the court hear Nebraska's complaint on just one of three claims.

Nebraska alleges Colorado has been allowing junior-priority water users to pump groundwater "out of priority" through so-called augmentation plans. Such plans allow junior-priority water users to take water if they replenish an equivalent amount back into the river later.

The U.S. Department of Justice recommended the court appoint a special master in the case, or an independent expert who makes recommendations to the high court on resolving the dispute.

"Because Nebraska raises weighty, but factual, questions about Colorado's Article IV compliance, the court should grant the motion as to that claim and refer it to a special master," the DOJ said in a filing with the Supreme Court.

Article IV of the Constitution establishes the relationship between the states and the federal government along with other states.

According to information from Nebraska Attorney General Mike Pilger's office, the two states have been negotiating the details of the canal for "many years" but Colorado officials have yet to agree on "basic things" including location and size of the canal or how much water flows through it.

Colorado Attorney General Phil Weiser sent a letter to Sedgwick County commissioners where the canal needs to begin, allegedly threatening legal action if Nebraska proceeds with the canal project, the lawsuit said. The letter said Colorado is "prepared to defend its rights under the South Platte River Compact."

Nebraska alleges in the lawsuit that Colorado is "essentially racing to develop as much of the water supply in excess of Nebraska's Article IV right as possible."

So, by developing the water resources before Nebraska can finish the canal, the lawsuit said Colorado is effectively attempting to claim water that the compact reserves for Nebraska.

Nebraska said in the lawsuit that for the first time in 50 years, at least one irrigation district in the state was forced to shut down most of its surface water irrigation because of lack of supply.

In 2022, the lawsuit said, there were more than 100 days when flow at the Nebraska/Colorado border fell below the required 120 cubic feet per second.

Nebraska allocated about $600 million to build the canal in Perkins County to secure non-irrigation season water rights. The lawsuit claims Colorado's developments will lead to a 90% reduction in river flows during the non-irrigation season.

Colorado's population in the South Platte River and Denver metro basin is projected to grow from about 3.8 million in 2015 to 6 million by 2050, the lawsuit said, which would create a water supply shortfall of more than 400,000-acre feet for agriculture uses.

Read more about the ongoing dispute here, https://www.dtnpf.com/….

Todd Neeley can be reached at todd.neeley@dtn.com

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