Firefighters tackling the deadly LA wildfires since January 7, have faced challenges due to a limited supply of freshwater. When winds calm down, experienced pilots in planes called Super Scoopers scoop up 1,500 gallons of seawater at once, delivering it with pinpoint accuracy to douse the flames. But why didn’t they use seawater from the start, especially when just a few miles from the fire there are hundreds of thousands of liters available?
Can seawater be used to fight fire?
Seawater can be used to fight fires, particularly in coastal areas where freshwater may be scarce. It is commonly used in fighting large-scale fires like wildfires, especially when aircraft are involved. The high salt content in seawater, however, can cause damage to equipment, vegetation, and soil. It is generally avoided for fires that need to be contained without further environmental impact.
While seawater is effective in suppressing flames, it’s typically a last resort due to its corrosive nature. In some cases, firefighters will mix seawater with fire retardants to reduce the risk of salt damage. The decision to use seawater depends on the type of fire and its location, with freshwater being the preferred option whenever possible.
Why is seawater being used to extinguish the LA Wildfire?
Due to the enormous scale of the wildfire, which has already consumed thousands of acres, and the strong winds that continue to fuel the flames, the use of seawater is an emergency resource. Although the salt in seawater causes damage to the equipment used to fight the fire, the reality is that there is a low availability of freshwater to tackle the blaze, again due to its massive and unusual scale.
Why is seawater not normally used to extinguish fires?
California boasts the world’s largest civilian firefighting aviation fleet, with over 60 aircraft, according to Cal Fire. However, only a few of these planes are equipped to scoop water from the Pacific Ocean.
Some firefighting aircraft are designed solely to carry and deploy fire retardants, not water. For those that can carry water, seawater is rarely used due to its salt content, which can damage equipment. Seawater can also pose problems for other firefighting tools, as fire hydrants and many other devices are made of metal, which rusts when exposed to water and oxygen.
Another reason seawater is a last resort in firefighting is its potential environmental impact. The long-term effects of seawater on trees and soil are not yet fully understood. In an interview with the independent nonprofit news organization The Conversation, Patrick Megonigal, an ecosystem ecologist at the Smithsonian Environmental Research Center explained that “lab experiments suggest that salt causes clay and other particles to disperse and move through the soil. These changes in soil chemistry and structure can persist for years.”