On The Colorado - Articles

REPORTS FROM RETURNING RAPIDS PROJECT

November, 2024 - New and profound sediment slump features at Narrow Canyon

NEWS

December 19, 2024 - New rapid forms in Cataract Canyon after slump. By Heather Daigle for Moab Sun News.

SLUMP FEATURES IN UPPER GLEN CANYON
Movies from 2022 approaching the side canyon known as Farley Canyon

Movie 01: Navigating dewatered mud island rapids. mov.
Movie 02: Cascading, dewatered mud flows. mov.
Movie 03: Navigating islands, dewatered slump features & dunes. mov.

CONSIDERATIONS ABOUT CONTROLLING THE COLORADO RIVER WITH MASSIVE INFRASTRUCTURE

Hoover Dam and Glen Canyon Dam

The primary purposes of Hoover Dam and Glen Canyon Dam is to contain large snow melts of 4 to 5 months, and up to a maximum total volume of 30 million acre-feet. (We now know that 45 million acre-feet is possible as of this investigation.)
The secondary and tertiary purposes are to store water, and to store entrained sediment & organic detritus.
The fourth and fifth priorities are to generate electricity and provide opportunities for human recreation.
Hoover Dam is designed to release a total of 518,000 cubic feet per second. The maximum flood release is confined to one-month of spillway operations, and the spillways will require subsequent repairs.
Downstream of Hoover Dam, regulatory agencies allowed the historic floodplain of the Colorado River to be occupied at the river level of 28,000 cubic feet per second.
The levee below Imperial Dam has a design capacity at 80,000 cubic feet per second. The purpose of the levee is to assure the flood flow will not be captured by a structural depression called the Salton Sink (below sea level).
At Glen Canyon Dam there are eight 15-foot-diameter steel penstocks for delivering water to the turbines in the powerplant. The centerline of the penstock intake is at elevation 3470 which is about 45 feet above estimated silt elevation after 150 years of reservoir operation. Minimum water surface for power operation is elevation 3490.
The river outlets at Glen Canyon Dam have a capacity of 15,000 cfs with the reservoir water surface at elevation 3,490 feet. The centerline of the intake is at elevation 3374 which is about 30 feet above the estimated 100-year silt level in the reservoir.
The original spillway capacity as of 1961: 276,000 cubic feet per second (cfs).
The spillway specifications as of 1984, after the spillway were repaired and modified with increased air slot capacity: 208,000 cfs.
The spillways at Glen Canyon Dam, in 1983, were compromised after six days of operations, and at 20% of capacity.
REFERENCES - Hoover Dam specifications by Elwood Mead; Glen Canyon Dam specifications by Ernest Schultz; Glen Canyon Dam repairs, 1983.