The health of our waters is the principal measure of how we live on the land — Luna Leopold
As the #ColoradoRiver shrinks, federal officials consider overhauling #GlenCanyonDam — The Los Angeles Times #COriver #aridification
The back of Glen Canyon Dam circa 1964, not long after the reservoir had begun filling up. Here the water level is above dead pool, meaning water can be released via the river outlets, but it is below minimum power pool, so water cannot yet enter the penstocks to generate electricity. Bureau of Reclamation photo.
A preliminary analysis of potential modifications to the dam emerged during a virtual meeting held by the federal Bureau of Reclamation, which is also reviewing options for averting a collapse of the water supply along the river. These new discussions about retooling the dam reflect growing concerns among federal officials about how climate change is contributing to the Colorado River’s reduced flows, and how declining reservoirs could force major changes in dam management for years to come…
Roerink and two other people who listened to the webinar told The Times that cost estimates for several alternatives ranged from $500 million to $3 billion. The agency will need congressional approval and will have to conduct an environmental review to analyze options. The Bureau of Reclamation’s presentation, given by regional power manager Nick Williams, included some additional alternatives that wouldn’t require major structural modifications of the dam. Those options included adjusting operations to maximize power generation at low reservoir levels, studying ways of using the existing intakes at lower water levels, and making up for the loss of hydroelectric power by investing in solar or wind energy…
Low-Level Power Intake with New Low Head Runners (Alternative 1a. via USBR)
According to a slide presentation shown at the meeting, officials see potential hazards in some of the six alternatives. Piercing the dam’s concrete to create new low-level or mid-level intakes, for example, would entail “increased risk from penetration through dam,” the presentation says. They also describe risks due to possible “vortex formation,” or the creation of whirlpools above horizontal intakes as the water level declines. Their formation could cause damage if air is pulled into the system. The presentation says one alternative would involve lowering the minimum power pool limit and possibly installing structures on the intakes to suppress whirlpools, but it said this still would not allow for the water level to go much lower.
A high desert thunderstorm lights up the sky behind Glen Canyon Dam — Photo USBR
