Dry Times x 2

A deeper dive into Glen Canyon Dam Data ~ the land desk

In response to Wednesday’s dispatch on hydropower waning across the Southwest as a result of the drought, dedicated Land Desk reader Jerry Zink pointed out that the Lake Powell surface-elevation graph was fine and good, but was less representative than a graph showing how many acre-feet of water are in the reservoir. He also noted that as the amount of water in the reservoir drops, so too does the generating capacity of the power plant in the dam (because water pressure drops, too).

Knowing a challenge when I saw one, I dived down the rabbit hole and came up with a few more graphs for y’all to ponder. So here you go:

This is the number of acre-feet of water stored in the reservoir. Storage in the lake is currently at only 34% of capacity. Source: US Bureau of Reclamation.

This graph shows how much power was actually generated by Glen Canyon Dam’s power plants each month. Unfortunately, the data only goes back to 1995, so…

… here’s a version of the storage graph starting at 1995, so that you can compare it to the power output. As you can see, power output and storage levels are matched up, more or less. But I wanted to dig down deeper, so…

I crunched some USBR numbers and came up with this, which basically shows the way the power intensity—or the generating capacity—of the dam changes according to how much water is in the reservoir. What this means is that as the lake drops, dam operators need to run more water through the turbines to generate the same amount of juice.

So, basically, this just reinforces the concern I expressed in the last post: Warming temperatures, dry times, and dropping stream and reservoir levels are diminishing the output from Southwestern hydroelectricity dams. And it’s happening just when that power is badly needed due to increased demand and the shutdown of some big coal power plants around the region in recent years.

It should be an interesting summer, power-grid-wise. We’ll be keeping you up to date.