Cloud seeding could be a cost-effective way to put a little more water in the Colorado River

LAUREN GILGER: In all of our reporting on drought and the heat in the Southwest, have you ever thought, “Man, it’d be nice if we could just make it rain right now. We really need some rain”?

Well, as you may or may not know, we actually can do that. It is called cloud seeding, and it’s being used here in Arizona and in states across the West to literally make clouds rain or snow.

But we’ll get into that in a moment. The question is, how much water can it add to our increasingly dry climate? Could it, for example, make a dent in the water supply headed to the Colorado River as negotiators continue to fail to make a deal to conserve the river’s water supply and threaten our collective water future?

For some insights on those questions and more, I’m joined by KJZZ’s Alex Hager, who covers water for us. Good morning there, Alex.

ALEX HAGER: Good morning, Lauren.

GILGER: All right, so let’s begin, Alex, with just an explainer. Like, how does cloud seeding work? There are two different kinds.

HAGER: Yeah. If there is one thing to know about cloud seeding, it is that it does not make water. It basically just helps it fall from the sky.

I’ll tell you what I mean. So there’s cold weather cloud seeding, and that is where you take tiny particles of a substance called silver iodide and you shoot them into clouds that already exist.

And then there’s water in those clouds, and it’s kind of not ready to fall. It’s not condensing yet. But once you add that silver iodide, it gives something for the water to bunch up around. And then it gets heavy, and then it falls as snow — usually in the mountains at high elevation.

Then we also have warm weather cloud seeding, which is pretty similar. That one, you usually have a station based on the ground, and instead of silver iodide, it’s sending up an electrical charge into the air that also causes water inside clouds to condense and then get heavy enough to fall as rain.

GILGER: OK, so kind of surprisingly simple.

How well does it work, Alex? Like, is there data on that big question of just how much water this could make come down from these clouds?

HAGER: Yeah, it is really simple. We are starting to get data on how much water it can make. A lot of what we’re gonna be seeing now and in the next few years is coming from Utah. They have the biggest, best funded cloud seeding program in the country. They have more than 200 stations that try to make snow fall in the mountains.

The state says it is able to boost annual snow totals by about 6-12%.

GILGER: OK, so a range and not a huge amount, but some.

OK, what about that other big question then, Alex? Like, could cloud seeding help us address the big problem we’re looking at here in the west right now, which is the water supply in the Colorado River, which is really in dire straits right now?

HAGER: That is the big question. Even in Arizona, when we’re thinking about the impact of cloud seeding, it is probably going to have more to do with the cloud seeding that is done very far away from here in the snowy mountains of Colorado and Utah and Wyoming because of the Colorado River. That river supplies more than 6 million people in our state, and more than 80% of the river’s water starts as snow.

So every year, when we’re thinking about how much Colorado River water will come to the Valley, will come to farms in the Yuma area, we are thinking about how much snow is falling in those high-altitude mountains.

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And right now, the management of the Colorado River is a big question mark. We’re in the middle of ongoing negotiations about its future.

It seems that the states that have to decide who gets how much are just stuck in those talks. And there are big questions about how much each state is going to get going forward, because there is not enough to go around under the current rules. And this is something that people are looking to as maybe a way to tweak how much there is to go around.

GILGER: Right. Maybe a little bit. OK. So if we’ve got a relatively simple technology here that can make clouds rain where we need them to rain — even if it isn’t a ton of rain — I have to ask, why isn’t this more widely used?

HAGER: So I’ve seen two main reasons come up. One is the fact that it isn’t really adding water. It’s just telling it where to fall. And because we are in a drought, that means across the West, a lot of times there is just less moisture in the air. So there’s less time that cloud seeding can be effective.

Even if you have the infrastructure and have the money to do it, if there aren’t clouds, it’s not gonna work.

GILGER: Not gonna work on a sunny day.

HAGER: Exactly. The other big thing is that we don’t actually have that much data on how effective it is. We’re starting to get more out of these big trials in Utah and elsewhere in the West. But even though the technology has existed since the 1940s, the really good data that can guide how we’re using it in this century really didn’t start coming out until 2018.

And the research that did start coming out then made it hard to tell how much cloud seeding was actually adding to the snow that falls naturally. It’s just really hard to measure. If you can only add snow when it is already snowing, it can be difficult to quantify exactly how much of that was a direct result of cloud seeding.

Alex Hager

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KUNC

GILGER: So what are the drawbacks here? Like, are there environmental concerns? Like, how much is it that we do not know?

HAGER: Right now, there do not appear to be big, screaming, obvious drawbacks when it comes to safety. You know, proponents of cloud seeding say we actually do have pretty good data on how safe it is. So even when you have silver iodide entering the water atmosphere, it is way clear of the level that the EPA considers safe for drinking.

Right now, the biggest question is just getting better information about how much water cloud seeding can actually add. But our region is getting so dry, it is a problem for so many people across the Southwest. Policymakers are kind of just throwing the kitchen sink at this problem, and this is part of the kitchen sink.

You know, there’s one Colorado River negotiation who often says, “Look, we’re not gonna fix the water problem with a silver bullet, but we might be able to fix it with silver buckshot.” And in my opinion, I think cloud seeding could be part of that silver buckshot.

GILGER: OK, part of the bigger picture. There are stories, Alex, once in a while about whether or not cloud seeding leads to flooding. Like this came up at the state Legislature here in Arizona when there was historic flooding in Globe. What are the safeguards?

HAGER: Yeah. Cloud seeding programs generally do not get off the ground without the state permitting and regulating them. And part of that regulation is really strict guardrails specifically designed to stop cloud seeding from making flooding worse.

So a lot of those regulations say, look, if a huge storm is on the way, you’ve just got to shut off the cloud seeding gear, make sure it’s not contributing to a “too much water” problem. That seems to be the case in Globe.

You generally see the effects of cloud seeding show up within a really short time period, maybe half an hour. And the cloud seeding near Globe ended four days before that big flooding there.

Also, at the end of the day, cloud seeding experts say that technology just can’t add huge quantities of water, and the amount that it would take to cause big flooding anywhere, that’s something that generally only naturally occurring rainstorms are really capable of producing.

GILGER: OK. Are there efforts here in Arizona to fund this then, to fund cloud seeding? It sounds like there is cloud seeding happening here in our state.

HAGER: And there has been for a while. Different agencies have dabbled in cloud seeding going back to the 1940s, kind of on and off over the decades. One of the best recent examples we have is there was a big trial program in Pinal County last summer.

The numbers are a little fuzzy, but Pinal County thinks it added about half an inch of rain over three months. One of the big conclusions that came out of Pinal County is that it added water for incredibly cheap. So the experts who ran that study said it cost about $3 to add an acre-foot of water. That’s the unit we usually use to measure water in rivers and reservoirs. So $3 for 1 acre foot.

Now, by comparison, if you wanted to generate 1 acre-foot of desalinated ocean water, that would cost you multiple thousand dollars. It costs multiple thousand dollars per acre foot to build a bigger dam to capture more runoff.

So because it is so cheap by comparison — and water managers are kind of looking everywhere for every solution they can get — I expect we will probably see some more cloud seeding in the future.