Aspinall Unit update: 300 cfs in the Black Canyon


From email from Reclamation (Erik Knight):

Gunnison River flows at the Whitewater gage continue to stay above 1000 cfs and are forecast to remain that way for the upcoming weeks. The baseflow target for endangered fish, as measured at the Whitewater gage, is 790 cfs for the month of October. With tributary flows continuing to support flows in the lower mainstem of the Gunnison River, now seems like a good time to reduce releases from the Aspinall Unit to save the limited storage remaining in Blue Mesa Reservoir. Therefore releases at Crystal Dam will be reduced today, October 1st, by 150 cfs. This will bring flows on the Gunnison River within the Black Canyon down from 450 cfs to 300 cfs. Flows at the Whitewater gage are expected to decline towards 800 cfs after this release change.

From The Grand Junction Daily Sentinel (Gary Harmon):

The U.S. Bureau of Reclamation started banking water Monday for next spring, squeezing releases from Crystal Dam.

Officials with the Aspinall Unit on the Gunnison River reduced flows down the river by 150 cubic feet per second, an amount that will cut flows on the river through the Black Canyon of the Gunnison National Park from 450 cfs to 300 cfs.

“We’ll be down near minimum flows as the river goes through the park,” said Erik Knight, a hydrologist with the bureau’s Grand Junction office.

The bureau usually begins restricting flows Oct. 1, but this year it also has to factor endangered fish downstream into its management of the river.

Tributary flows are contributing enough water to the river below the Gunnison Forks that the river was running at 1,000 cfs at Whitewater.

The change will reduce flows at Whitewater to about 800 cfs.

The bureau is hoping to end December with about 315,000 acre-feet of water stored behind Blue Mesa Dam.

The maximum wintertime storage is 581,000 acre feet and, “We’re well below that,” Knight said.

“We’re just hoping for next springtime” to swell the reservoirs again.

Paonia Reservoir, which is used for irrigation, will begin filling this November.

It generally fills each year and is expected to do so again this winter and spring, Knight said.

“It’s the bigger reservoirs where we have a problem,” he said.

More Aspinall Unit coverage here and here.

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