An even bigger threat is looming behind California’s fires

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Fires in and around Los Angeles continue to rage as gusting Santa Ana winds drive the flames through brush and into neighborhoods. Two major blazes, the Eaton Fire and the Palisades Fire, have combined burned almost 40,000 acres since last week. Another fire, the Auto Fire, erupted Monday evening in Ventura County. The fires have killed at least 24 people.

The extraordinary scale and speed of the blazes have overwhelmed responders, even in a region with a long history of fighting wildfires. That was evident last week as firefighters worked to contain the Palisades Fire when they found that some of the fire hydrants in the Pacific Palisades neighborhood ran dry. 

The Los Angeles Times reported that the 114 water tanks that supply the city’s water were full before the fires ignited. But when the blazes ignited, firefighters were using so much water for so long, faster than the tanks could refill. That made it hard to keep the water flowing, particularly at higher elevations. 

“Four times the normal demand was seen for 15 hours straight, which lowered our water pressure,” Janisse Quiñones, CEO and chief engineer of the Los Angeles Department of Water and Power, told the Los Angeles Times. 

Water, however, is always a political issue in Los Angeles. The region has contended with water scarcity since it was founded, yet has also faced extensive flooding during intense downpours. City officials and local politicians were quick to criticize the city’s underinvestment in its water infrastructure. 

However, the fires have also become another reason to litigate a long list of grievances with California’s decisions around water: taking down dams, not building enough reservoirs, protecting a tiny fish. It’s important to understand that these factors have little relevance to the ongoing fire response. “I think some of the conversation is so unrelated to fire hydrants in LA it’s hard to know where to start,” said Faith Kearns, a water and wildfire researcher at the Global Futures Laboratory at Arizona State University. 

Nonetheless, California is facing threats to its water infrastructure that will only intensify after the flames die down. The fires are already degrading drinking water in the afflicted region and will continue to impede the recovery. And as the climate changes, water stresses on the state are mounting alongside the growing threat of more major fires in the future.

Why water isn’t always helpful with wildfires

The ongoing fires around Los Angeles are challenging for several reasons. A big one is that the weather has been obstinately uncooperative, with powerful winds blowing embers miles across a region that’s unusually dry. Those embers are landing on a bumper crop of vegetation primed to burn after a sequence of intense rainfall, record-breaking heat, and a dry start to winter over the past year. 

Another big factor is that the fires are burning in both wildlands and in urban areas. Firefighters use different tactics depending on the environment. For structure fires in a city or suburbs, the typical response involves firehoses, pump trucks, and lots of water. 

But amid the chaparral, grasses, and trees, the preferred tools are shovels, axes, drip torches, and bulldozers. The core strategy is not necessarily to extinguish the fires but to contain them with fire breaks, denying fuel to the flames. Aircraft that drop water and flame retardants can help on the margins as blazes encroach on neighborhoods, but there aren’t enough of them to contain fire fronts that span miles, while smoke and high winds can often make it too dangerous to fly. 

When the recent fires reached the built environment around Los Angeles, they exploded as winds blew up to 100 miles per hour, creating a disaster that has more in common with a hurricane than a house fire. Dozens of buildings ignited across the county at once, leaving urban firefighters facing advancing fire fronts like those in the wilderness. Their tools and tactics could not keep up. More than 12,000 structures have burned so far in the fires. 

“Our traditional urban water infrastructure and supply was just largely not meant to fight fires like this,” Kearns said. “It was designed to put out a fire at a single house or a few structures, not thousands of houses during really high winds.”

The more pressing constraint is a shortage of personnel to deal with the scale of the fires, particularly responders with the training to contain infernos in such difficult conditions. Firefighters from across the state, around the country, and even from Canada and Mexico are now assisting with the response. California is also deploying prison inmates to help contain the blazes.    

“LA County and all 29 fire departments in our county, are not prepared for this kind of widespread disaster,” LA County Fire Chief Anthony Marrone said during a press conference last week. “There are not enough firefighters in LA County to address four separate fires of this magnitude. … The LA County fire department was prepared for one or two major brush fires, but not four, especially given these sustained winds and low humidities.” 

California’s fire and water challenges are getting tougher

The raging infernos are likely to create longer lasting problems for the region’s water supply. Kearns co-authored a 2021 report that found that drinking water suffered contamination in the wake of several major California wildfires. 

There are several mechanisms for this. Kearns explained that when water pressure drops in the municipal water supply like it did in Los Angeles last week, untreated waste water can backflow into mains. This means that pathogens and other contaminants can enter water lines. Several communities in Los Angeles County have advised residents not to drink tap water.

The ash from the fires can also enter surface water supplies like reservoirs and aqueducts. That ash can contain toxic chemicals. Some of the flame retardants used to contain the fires can also allow hazardous substances like benzene to enter the water supply. 

Fires can melt PVC plumbing, which can introduce long-lasting contaminants into water. Weather conditions have been exceptionally dry so far, but when rain does pick up, that can wash fire debris into the water system, stressing water treatment plants.

Southern California and the state as a whole are also facing water scarcity in the years to come. 

California’s infamous housing shortage is pushing more people to live in areas likely to burn. By one estimate, there will be 645,000 new homes built in areas rated as “very high” wildfire severity zones by 2050. More people living in wildfire prone regions increases the chances of starting a wildfire and raises the damage tally when those blazes inevitably ignite. 

On top of that, California is experiencing long-term changes in its climate that are poised to expand and worsen wildfire risk while exacerbating water scarcity. Rising average temperatures are causing trees and shrubs to dry out and more readily ignite. 

Thomas Harter, a professor at the University of California Davis studying water infrastructure, said that the state has shifted between wet years and dry years in equal measure through much of its history. 

But now, the swings between rainfall and drought are starting to become more aggressive, a phenomenon dubbed “whiplash.” That often means that there is too much water to save during wet periods and not enough to go around in dry spells. 

And since the start of the 21st century, the number of dry years have begun to outnumber the wet years, and the dry years are getting drier. 

In addition, as average temperatures rise, there’s more evaporation from surface water stores and there’s more evapotranspiration from vegetation, which means trees, grasses, and shrubs retain less water. 

The amount of water in California’s reservoirs varies year to year with rainfall, and right now most of them are at or above the levels that are typical for this time of year. 

The compounding effects of climate change on California’s water are more apparent underground. With more dry years than wet years, the state’s thirsty agriculture sector draws on groundwater when surface supplies run low. Groundwater stores recharge slowly over thousands of years, so they’re building up a deficit as aridity increases. 

The result is that California can’t simply dam its way out of water scarcity and will have to make some difficult decisions about who gets to use water. “There is no two ways around the fact that we have to dial back the amount of water we are using,” Harter said.

Even if California were to build more reservoirs, they wouldn’t be enough to counter its growing wildfire problem. “Water is expensive to get there, expensive to distribute, expensive to store to prevent and douse these very extreme [fire] events,” Harter said. “The difference is very minimal in terms of what can be achieved.” It’s also important to remember that fires are a natural part of ecosystems throughout California, so trying to eliminate them entirely can create more problems like allowing fuel to build up to very high levels.

Reducing the threat from wildfires instead requires a suite of approaches that will take time, cost money, and create new political friction points. That includes performing controlled burns to reduce fuel loads, building codes that require more fire-resistant materials, limiting where people can live in the first place, accurately pricing risk in insurance policies, and curbing humanity’s output of heat-trapping gases.