Will Colorado River Cuts Create A New Dust Bowl?

Courtesy of The Land Desk, commentary on the impact that the recently agreed upon Colorado River cuts may have:

  1. What effect will fallowing thousands of acres of fields have? Will it lead to another Dust Bowl? 
  2. Is the electricity from the dams used to deliver water (e.g. to power the pumps for the Central Arizona Project)?
  3. And what purpose do the two reservoirs (Powell and Mead) serve in the system and how does that factor into the bargaining between the states?

I’ll just explore the first two today, since that’s all I have room for.

My short answer for question #1 is: I don’t know. One of the problems with the deal is that very few details have been made public, so it’s difficult to understand what ramifications it might have. 

But we do know that the Lower Basin states plan to come up with 3 million acre-feet of water over three years — or about 1 million acre-feet per year — by paying water users to slash consumption. Federal funds will be used to reimburse folks for 2.3 million acre-feet of those cuts, while state, local, or other funds will be used for the remaining 700,000 acre-feet. It’s fair to guess that a bulk of these savings will be realized by paying farmers not to irrigate their crops, since agriculture is by far the biggest user of Colorado River water, and that makes more logistical sense than paying folks not to water their lawn. So that’s a good place to start.

I’ve also read reports saying the Imperial Irrigation District, the largest single water user in the Basin, plans to give up 250,000 acre-feet per year (which will be included in the above amounts).

One of the most abundant crops in the Colorado River Basin is hay, primarily alfalfa. It is also one of the thirstiest crops. Growing one acre of alfalfa guzzles around four acre-feet of water per year, depending on location, climate and length of growing season. In Colorado’s high-elevation, cool San Luis Valley, alfalfa consumes about two acre-feet per year; in California’s sea-level Imperial Valley — one of the hottest places in the nation — the crop can require more than six acre-feet of water per year.

Since the fallowing is likely to occur in hot, dry southern Arizona and California, we’ll go with the six-acre-feet-annually figure. That would mean that in order to reach the target water cuts, irrigation would have to be stopped on a total of 167,000 acres of alfalfa fields, or roughly three-fourths the size of the Salton Sea. Targeting less thirsty crops would require fallowing a larger amount of acreage. About 42,000 acres of that would be in the Imperial Irrigation District, assuming the fields they fallowed were alfalfa. For some more context: An MIT study found you’d need 90,000 acres of solar panels to replace the Diablo Canyon nuclear power plant’s generation.

So, yeah, it’s a lot of acreage, and ceasing irrigation on that land could very well turn it into desiccated weed patches. Maybe it won’t be Dust Bowl kinda stuff for now, but it could get ugly, especially in a dry summer. In the San Joaquin Valley in California, for example, a groundwater management program (no relation to the Colorado River crisis) is forcing farmers to fallow fields, which is leading to serious dust and air quality problems

The Imperial Valley is next to the Salton Sea, where the air — and residents’ lungs — is already thick with dust. Fallowing all of the Valley’s alfalfa fields surely would further exacerbate the problem. At this point it’s not clear where fields will be fallowed, only that some will be in California and some in Arizona (Nevada uses almost all of its Colorado River water for municipal uses in Las Vegas and surrounding communities). 

Media outlets have reported that the states plan to pay those farmers $1.2 billion from the federal Inflation Reduction Act. That would put a $521 price tag on each acre-foot of water not going onto a field. Using the 6 acre-foot per acre of alfalfa figure, that would mean an Imperial Valley farmer could get more than $3,000 per acre to not grow anything.  

That’s not a bad deal. According to the UC Davis cropland data layer site, Imperial Valley farmers harvested 144,000 acres of alfalfa hay in 2020. They produced 1.14 million tons of alfalfa hay, valued at $200.44 million — or an average of $1,391 per acre. In other words, the farmers could bring in twice the revenue for not farming than for farming their acreage.

But it would also reduce the supply of alfalfa, causing prices to increase, which would likely ripple through the beef and dairy industries, where most of that alfalfa goes. That, in turn, could eventually make its way down to the ice cream and cheese aisles at your local grocery store. 

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.

This entry was posted on Tuesday, May 30th, 2023 at 2:28 am and is filed under Colorado River, United States.  You can follow any responses to this entry through the RSS 2.0 feed.  Both comments and pings are currently closed. 

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