The South Platte River is seen from Grant-Frontier Park on Thursday, Sept. 30, 2021 in South Denver. (Olivia Sun, The Colorado Sun)

By Grant Schulte, The Associated Press

LINCOLN, Neb. — Colorado’s governor is warning he will “protect and aggressively assert” his state’s water rights after Nebraska Gov. Pete Ricketts announced a plan to spend $500 million on a canal and reservoir project that includes claiming access to land in Colorado under a 99-year-old compact between the states.

Colorado Gov. Jared Polis said he will work with Nebraska but wants more details about what the state has planned. His comments came as Ricketts released a proposed state budget Thursday detailing how he intends to fund the project.

“We will continue to protect and aggressively assert Colorado’s rights under all existing water compacts,” Polis said in a statement Wednesday evening. “Colorado has been in full compliance with the South Platte Compact for the 99 years the agreement has been in place, and water has not and is not being withheld from Nebraska.”

Ricketts and Nebraska Attorney General Doug Peterson announced the water plan after Colorado released a report that identified 282 new water projects within the South Platte River Basin. Ricketts and Peterson warned that those projects could reduce its water flows from the river by as much as 90% and threaten Nebraska’s water supplies.

“We must act to preserve, protect, manage, and steward our water supply for our future Nebraskans,” Ricketts said Thursday in his annual State of the State address to lawmakers.

The South Platte River Compact, approved in 1923, is a water-sharing agreement that entitles Nebraska to 120 cubic feet per second from the river during the irrigation season between April 1 and Oct. 15, and 500 cubic feet per second during the non-irrigation season.

Under the compact, Nebraska can build, maintain and operate canals within Colorado’s borders that divert water from the South Platte River for use by Nebraska. It also gives Nebraska the power to buy land from Colorado landowners or gain access by invoking eminent domain. Nebraska’s move is likely to trigger lawsuits.

Polis said Ricketts’ comments “seem to reflect a misunderstanding of Colorado’s locally driven water planning process,” and that the projects identified “should not be taken as formally approved projects.”

“We hope to more fully understand Nebraska’s concerns and goals, as so far as those concerns and goals are quite simply hard to make sense of,” Polis said. “Our longstanding compliance of and respect for the water agreement between our states on the South Platte River remains intact and we hope that our partners in Nebraska will show that they share that respect.”

Ricketts released a budget plan Thursday that would pay for the canal project by taking $400 million out of the state’s $1.5 billion cash reserve fund and using $100 million in federal pandemic relief money.

The project would include a canal in rural Perkins County in southwest Nebraska and storage facilities. Some of the infrastructure would sit on the Colorado side of the border, and might require the state to invoke eminent domain against private landowners.

Any water fight between the states could last for years. Nebraska spent decades in a water fight with Kansas over access to the Republican River, which runs through Colorado, Nebraska and Kansas. The lawsuits revolved around a similar compact with the three states that was approved in 1943.

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