Arkansas River Basin

The Arkansas River Basin covers a huge territory, more than 28,000 square miles, encompassing more than a fifth of Colorado’s total land area. The Arkansas River flows from its headwaters near Leadville through the Front Range cities of Cañon City and Pueblo before unspooling onto the Eastern Plains and crossing into Kansas near the town of Holly. Eventually, the Arkansas River flows into the Mississippi River on its way to the Gulf of Mexico.

Portion of Colorado’s total land area covered by the Arkansas River Basin

In the upper basin, uses like trout fishing and whitewater rafting dominate—Browns Canyon National Monument between Buena Vista and Salida is among the most popular whitewater rafting destinations in the country. The Lower Arkansas River is a water source for towns and cities like Pueblo and Colorado Springs, though they rely primarily on transbasin diversion water, brought over through the Fryingpan-Arkansas Project and conveyed through the Arkansas River.

The river also supports a longstanding Eastern Plains agricultural economy. Grassland covers about 67 percent of the basin, and a large amount of that is devoted to agriculture, with one-third of agricultural lands requiring irrigation. Major water storage projects in the basin include John Martin Reservoir, Pueblo Reservoir, Great Plains Reservoir, and others.

Water users representing these diverse interests and from every county in the basin convene through the Arkansas Basin Roundtable which serves as a forum for discussing regional and local water issues and planning.

Water use in the Arkansas Basin is constrained by the following compact:

The Arkansas River Compact (1948): An agreement between Colorado and Kansas, which prevents Coloradans from depleting the river’s flow at the Kansas border below 1948 levels. This restriction prompted Colorado to adopt new rules in 2011, mandating that any farmers that increase their consumptive use of water by adopting more efficient irrigation technology must purchase augmentation water and return it to the river to ensure that the timing and amount of return flows to the Arkansas remains unchanged.