High-flow experiment to build sandbars on Colorado River

The latest experiment to rebuild sandbars and beaches on the Colorado River through Grand Canyon began last weekend and was expected to drop the level of Lake Powell by 2.5 feet by the time it ended last night at 7 p.m.

[Right, high-flow experiment in 2008.  Credit, T. Ross Reeve, US Bur. of Reclamation]

Schedule & Duration

• Nov. 18 - begin upramp to powerplant capacity
• Nov. 19 - bypass tubes open at 12:00 p.m. - Nov. 23 at 7:00 p.m.
• Total duration: 5 days; 1 day at peak release

Ramp Rates

• Ramp up: 1,500 cfs/hr from 9,000 - 42,300 cfs
• Ramp down: 200 cfs/hr from 42,300 cfs to 31,300 cfs
• Ramp down: 1000 cfs/hr from 31,300 cfs to 27,300 cfs
• Ramp down: 1,500 cfs/hr from 27,300 cfs

HFE Release Details

• Maximum total release: 42,300 cfs
• Powerplant capacity: 27,300 cfs
• River outlet tubes: 15,000 cfs
• Hydropower generation units: 8
• River outlet tubes: 4

Releases and Lake Elevation

• Releases will range from 7,000 - 9,000 cfs prior to and after the HFE
• Lake elevation is projected to decrease by 2.5 feet