Interstate Compacts


Interstate compacts, which are agreements between two or more states, govern specific interactions among those states and require consent by the U.S. Congress.

The State of Colorado is party to the following interstate compacts and equitable apportionment decrees:


Arkansas River Basin

Arkansas River Compact of 1948 

The compact protects all water uses in existence in 1949 and apportions the benefits of John Martin Reservoir between Colorado and Kansas. 

History of the Arkansas River Compact


Colorado River Basin

Colorado River Compact and Upper Colorado River Compact

These compacts allow Colorado to use up to 3.85 million acre feet (MAF), provided the Upper Basin does not cause the flow at Lee Ferry, Ariz., to fall below 75 MAF, based on a 10-year running average (7.5 MAF/year). To learn more, see the Coordinated Long Range Operating Criteria.  Learn about Compact Administration in this presentation.

La Plata River Compact

This compact apportions the waters of the La Plata River between Colorado and New Mexico, by allowing the unrestricted right to use waters by both states between December 1 and February 15, and allocating specific flows and deliveries between February 16 and November 30.

Animas-La Plata Compact

This compact provides agreements that allow for the operation of the Animas-La Plata Project.

History of the Colorado River Basin Compacts


North Platte River & Laramie River Basins

North Platte River Decree

The North Platte Decree limits Colorado’s use of North Platte River water.

Laramie River Decree

The Laramie River Decree limits Colorado’s diversions to 49,375 AF/year in the Laramie River Basin.


Republican River Basin

Republican River Compact

Colorado’s consumptive uses are limited to 54,000 AF, plus all uses from Frenchman and Red Willow Creeks.


Rio Grande River Basin

Rio Grande Compact

The compact establishes Colorado’s obligation to ensure deliveries of water at the New Mexico state line and New Mexico’s obligation to assure deliveries of water at the Elephant Butte Reservoir, with some allowance for credit and debit accounts.

Costilla Creek Compact

The compact establishes uses, allocations and administration of the waters of Costilla Creek in Colorado and New Mexico.


South Platte River Basin

South Platte River Compact

The compact establishes Colorado’s and Nebraska’s rights to use water in Lodgepole Creek and the South Platte River.


In addition, the Director of the Colorado Water Conservation Board (CWCB) is a voting member of the Arkansas River Compact Administration, and CWCB staff provide engineering and legal advice to the Administration. Staff members also are designated representatives to the Engineering and Legal Committees of the Upper Colorado River Commission.