1

South Platte River Compact

The South Platte River Compact, signed by Colorado and Nebraska in 1923, defines the States' rights and responsibilities with respect to the river. The Compact apportions to Colorado the full and exclusive use of the Upper Section (the area west of the Washington/Morgan County line). The Compact provides Nebraska with specified rights regarding the Lower Section. During the irrigation season, defined as April 1 through October 15, Nebraska has a priority for 120 cubic feet per second ("cfs"). Nebraska is not guaranteed a fixed amount of water. Instead, the Compact provides Nebraska a place in line to receive water up to that rate, when and if available.

Map of the South Platte River, highlighted in Colorado and Nebraska. The river is shown divided into upper and lower sections, with the lower section occurring in the northeast corner of Colorado

Map of the South Platte River - PDF

While South Platte water flows into Nebraska during the non-irrigation season, Nebraska currently has no legal right to demand that water from Colorado. The Compact allows Nebraska to obtain a right to divert water during the non-irrigation season if it builds a canal. Specifically, Nebraska may build the Perkins County Canal to divert up to 500 cfs of water, which it may only use for irrigation. The canal has a more junior priority than Nebraska's irrigation season rights. Without the canal, Colorado has full and uninterrupted use and benefit of the river during the non-irrigation season.

For a century, the States had little cause for discussion regarding the Perkins County Canal. According to Nebraska, insufficient funding and the scale of the project caused Nebraskans to abandon the few attempts they made to pursue the canal. In 2022, against the backdrop of long-term drought, Nebraska again started exploring the concept of a canal. In 2023, the Nebraska Legislature appropriated money for its design and construction.

United States Supreme Court Filings

On July 16, 2025, Nebraska requested the United States Supreme Court’s permission to file a lawsuit against Colorado regarding the South Platte River Compact. On October 15, 2025, Colorado filed a response opposing Nebraska’s request. The Supreme Court has yet to make a decision on Nebraska’s request.

Environmental Permitting

Nebraska recently engaged with the United States Army Corps of Engineers (“Army Corps”) to obtain a permit for the Perkins County Canal under section 404(b) of the Clean Water Act. The Army Corps held its first informational meeting on October 1, 2025 and plans to initiate the environmental impact statement (“EIS”) process in late 2025. The Colorado Department of Natural Resources has requested cooperating agency status. This process is in the early stages, with environmental review and permitting estimated to take until December 2028, assuming no delays.

Platte River Recovery Implementation Program

The Platte River Recovery Implementation Program (PRRIP) was established through a cooperative agreement between the states of Colorado, Nebraska, and Wyoming and the Department of Interior to address the needs of four federally listed species using the Platte River Basin while allowing water development to continue and occur. The species are the endangered whooping crane and pallid sturgeon, the threatened piping plover, and the interior least tern (delisted in 2021). The program provides Endangered Species Act (ESA) compliance for water related activities in Colorado, Nebraska, and Wyoming.

News and Events

  • Governor Jared Polis and Colorado Attorney General's October 15 Press Release
  • Colorado DNR South Platte Compact Community Update Meeting:
    Sedgwick County Community Center,
    102 W 6th St, Julesburg, CO
    November 10, 5 pm
     

Media Inquiries

Contact Chris Arend, chris.arend@state.co.us