The Shoshone Water Rights Permanency Deal: Structure, Strategy, and Basin Implications

The Colorado Water Conservation Board (“CWCB”) recently approved an agreement that would convey to the state agency interest in the Shoshone Hydropower Plant’s senior and junior Colorado River water rights for instream flow use thereby permanently preserving flows in the river.

The powerplant’s water rights are non-consumptive, meaning the plant returns 100% of the flows it uses to the river. The senior right has an appropriation date of 1902 and is decreed for 1,250 cfs. It is the oldest Colorado River right in the State of Colorado, and the oldest mainstem right in the Upper Basin, making this a strategic move for streamflows in the State of Colorado and helping to protect base flows for the Colorado River Basin. Because of the senior status of the right, the state must keep enough water to meet that right­—the administration of that senior call effectively moves 33,100–36,800 acre‑feet of water downstream past other potential diverters, all the way to the Utah state line and ultimately toward Lake Powell. The junior right has an appropriation date of 1929 and is decreed for 158 cfs.

The proposal requires three transactions: