2. The second point Ann made was that moving water from the Colorado River to fields and cities takes a lot of energy, including the power generated by the dams on the Colorado River. So when irrigators reduce their Colorado River water use it’s leaving more water in the river, which can generate more energy when run through the dams’ turbines, which can move more water to the fields … Woah, I am getting dizzy here. 

It’s a classic example of the water-energy nexus or, in this case, the water-energy-water nexus, one of my favorite topics.

Glen Canyon, Hoover, and several other dams on the Colorado River system are hydroelectric, meaning as water runs through them, it can be routed through turbines, generating power. As reservoir levels drop, so does the power generation capacity of the dam. And if the reservoir levels fall below the openings to the penstocks — or tubes leading to the turbines — then power production ceases altogether.

This freaks folks out in these climate changed times for good reason: The warmer it is, the more power we need to run air conditioners, and the more water irrigators need to put on their crops, meaning more power is needed to move that water. But the warmer it is, the lower the reservoirs and the less power we have. Ack!

The Central Arizona Project is one of the biggest water-moving projects on the Colorado River. Its pumps pull water from the Colorado River at Lake Havasu and move it 336 miles across the Arizona desert (in an uncovered canal, allowing massive amounts of water to evaporate), with a total elevation gain of more than 2,900 feet. That takes a buttload of energy. In fact, it takes so much power that the coal-fired Navajo Generating Station was built in large part to run the CAP pumps. 

2 million megawatthours: Annual power consumption of the Central Arizona Project pumps. 

2 million megawatthours: Annual power consumption of the five pumping stations on the Colorado River Aqueduct, which delivers water to Los Angeles and surrounding areas.

2.5 million megawatthours: Annual power output of Glen Canyon Dam in 2022

3.9 million megawatthours: Annual power output of Glen Canyon Dam in 2008

1.5 million megawatthours: Annual power output of Hoover Dam in 2022

259 million megawatthours: California’s annual power consumption.

The Navajo Generating Station was retired in December 2019, forcing the CAP to find power from elsewhere. Now the project gets 70% to 80% of its power from market forward and short-term purchases; 12% to 15% from the Salt River Project electric utility; 6% from Hoover dam; and 4% from a solar installation. About half the power for the Colorado River Aqueduct pumps comes from Hoover and Parker dams, with the rest coming from a mix of market purchases and hydroelectric generation within the Aqueduct system.

And then there’s the question of how much of the dams’ electricity goes toward moving water around. The Western Area Power Administration markets the electricity from Glen Canyon Dam and 56 other hydropower dams. Here’s a breakdown of who purchases that power:

While only 4% goes to irrigation districts, you can assume that portions of many of the other categories go to moving water or treating it. So if the hydropower capacity of the dams were to shrink or vanish altogether, all of these customers — including the water folks — would have to find new sources of electricity.