Cimarron River

Gunnison River Basin, CO

PROJECT PARTNER: Colorado Water Trust, Colorado Water Conservation Board, Western Rivers Conservancy
PROJECT TYPE: Water Management Agreements


Colorado’s Cimarron River originates in the Uncompahgre Wilderness—one of the state’s marquee wilderness areas containing multiple 14,000’ peaks. The headwater streams of the Cimarron River descend long glacially-carved valleys that are traversed by an extensive trail network, and ultimately the Cimarron drains into the iconic Gunnison River in an area renown for fly-fishing, the Gunnison Gorge and Black Canyon of the Gunnison National Park.

As the tributaries of the Cimarron emerge from the high mountains, water is diverted and used to support agriculture among the lower elevation valleys. In late summer the rights to divert water from the river can exceed the amount of flow in one such tributary, the Little Cimarron, and as a result an important stream reach typically goes dry each summer. While much of the Little Cimarron is known for robust trout populations and cold, clean water, assessments show that dewatered sections of the river produce a stressed, unhealthy ecosystem with poor water quality, few trout and unnaturally high water temperatures.

Through BEF’s Water Restoration Certificate® program (and with funding from other partners), critical funding will support a project led by the Colorado Water Trust, in partnership with the Colorado Water Conservation Board and Western Rivers Conservancy, to permanently restore flows to a 5-mile section of the Little Cimarron River that is severely dewatered each year during late summer. The flow restoration project allows water to be used for irrigation during the first part of the summer when flows in the river are ample. Then in the late summer, when flows drop, water will be protected in the river, transforming a formerly dry creek bed into a flowing stream. This restored water will reconnect flow between two vital sections of the river and will benefit fish, wildlife, and water quality—and still allow the underlying agricultural use of the water right, a novel win-win project for the Colorado River.

*This resource has been reviewed and found to meet the BEF Flow Program Certification Criteria for Evaluating Proposals to Secure Environmental Flows by the National Fish and Wildlife Foundation.