After fire hydrants ran dry during the wildfires in Los Angeles, listeners wondered why firefighters didn’t just use ocean water to begin with. On this episode of Possibly, we explain the tradeoffs of using the ocean to fight fires.
Megan Hall: Welcome to Possibly, where we take on huge problems like the future of our planet and break them down into small questions with unexpected answers. I’m Megan Hall.
We recently saw firefighters in Los Angeles struggling to put out massive wildfires that destroyed more than ten thousand homes.
One of the big problems- not enough water. Which made a lot of people wonder- LA is right next to the ocean- why can’t firefighters just use that?
We had Hamid Torabzadeh and Emma Mejia from our Possibly Team look into this question.
Hamid Torabzadeh: Hi, Megan!
Emma Mejia: Hello!
Megan Hall: So, why don’t we use ocean water to fight forest fires?
Hamid Torabzadeh: It’s a bit complicated so let’s step back.
Emma Mejia: The quick answer is, Firefighters DO use ocean water, but only when they run out of fresh water.
Hamid Torabzadeh: This actually happened during the Palisades Fire in LA– which grew more than 14,000 acres on its fastest day.
Emma Mejia: To try to picture just how fast that is, that’s almost eight football fields consumed by fire every minute!
Megan Hall: Wow.
Hamid Torabzadeh: And with a fire of that kind of speed, there was simply too much demand on the water supply, causing the water pressure to lower.
Emma Mejia: And so, the firefighters had to use ocean water.
Megan Hall: And how do they get that ocean water?
Hamid Torabzadeh: There are some super cool aircrafts made just for that.
Emma Mejia: People call them “super scoopers.”
Hamid Torabzadeh: Those used in the LA fires can scoop up more than fifteen hundred gallons of ocean water at a time. That’s about 4 hot tubs’ worth of water.
Emma Mejia: This is a huge help when firefighters don’t have enough fresh water to put out a rapidly growing blaze.
Megan Hall: That sounds like a great solution to me. But, why don’t they just use ocean water in the first place?
Emma Mejia: Good question. There’s a few reasons why ocean water is the last choice for firefighters.
Hamid Torabzadeh: To learn more, we talked with Pat Megonigal, a senior scientist and Associate Director for Research at the Smithsonian Environmental Research Center.
Emma Mejia: Pat and his team were curious about the effects of salt water on plants, trees, and soil, so they started an experiment—
Pat Megonigal: Where we draw water out of the Chesapeake Bay estuary and sprinkle it over this very large patch of forest. Once a year, we add the water for about 10 hours, watch it for a year, and then we repeat it the next year.
Hamid Torabzadeh: When they dump this water from this salty estuary, it’s pretty close to what happens when water from the ocean is used during forest fires.
Emma Mejia: Pat and his team kept dumping seawater every year, first once a year, then twice a year, and then three times a year.
Pat Megonigal: And there, after year three, we did begin to see the trees start to show signs of stress. Basically, they lost their leaves fairly early.
Megan Hall: So, that salty water was hurting the trees?
Emma Mejia: Exactly. Pat says that using seawater once for emergencies like wildfires probably won’t have a long-term impact on the forest.
Hamid Torabzadeh: But, it only took 3 years of these kinds of saltwater dumps to start making an impact.
Pat Megonigal: If you were to dump enough sea water, you know, at enough volume and at a high frequency, eventually it does affect the plants.
Megan Hall: But can’t rainwater just wash some of that salt away?
Emma Mejia: Super good point. If it rains a lot after firefighters use ocean water, more of the salt will get flushed out from the soil.
Hamid Torabzadeh: But of course dry places like LA don’t get that much rain.
Emma Mejia: And there’s something else to consider too. Pat says firefighters are wary of salt water.
Pat Megonigal: They prefer to use fresh water for variety of reasons, one of which is that it’s much easier on their equipment. Salt is just terrible for, equipment in general.
Megan Hall: Makes sense. So, it’s ok to use ocean water to fight fires if you have to, but it’s a last rather than first resort?
Emma Mejia: Yes, but the takeaway for protecting lives and homes is pretty clear.
Hamid Torabzadeh: For big, rapidly growing fires and when freshwater is not available, ocean water is a better choice than no water at all.
Megan Hall: Got it! Thanks, Hamid and Emma!
That’s it for today. You can find more information, or ask a question about the way your choices affect our planet, at askpossibly.org. You can also subscribe to Possibly wherever you get your podcasts or follow us on Instagram, Facebook, LinkedIn, X, or Bluesky at “askpossibly”
Possibly is a co-production of Brown University’s Institute for Environment and Society, Brown’s Climate Solutions Initiative, and The Public’s Radio.
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