The Challenges of Fighting Wildfires with Urban Water Systems

In the recent Southern California fires, municipal water systems struggled to meet the unprecedented demands made on them. Is a wholesale rethinking of these systems in order? We asked Wendy Broley, executive director of the California Urban Water Agencies, to tell us more.

First, can you talk a little bit about what happened in Southern California?

It's important to note that there was a confluence of different factors. We had a couple of great wet years with a lot of vegetation growth, then exceptionally dry conditions, followed by strong Santa Ana winds. So, the fires spread very rapidly and had a lot of very dry fuel. The winds made it difficult to fight from the air, and that's a critical facet of our ability to fight wildfires.

Water supply was not the issue. There was plenty of water: reservoirs are at above-average levels. Rather, the water distribution system was stretched beyond its limits. There was unprecedented demand on the system- at times, four times greater than typical-which caused the water pressure to drop. The infrastructure couldn't get water where it was needed fast enough.

Los Angeles was not the first city to experience this during a large-scale wildfire. Municipal water systems are not designed for fighting wildfires-they are designed for fighting structural fires. A system that could fight fires of this magnitude would be unlike anything that exists today, and it's almost a false premise to suggest that it should exist. It's something to be looked at comprehensively and holistically to determine how standards and codes need to shift under new and changing conditions.

How can we design municipal water systems to respond to the changing climate in densely populated urban areas and the wildland-urban interface?

Climate change is fundamentally changing circumstances, and we do have to adapt. Water is a factor in several climate risks, including drought, flooding, and wildfire. But we can't solve for one issue, like wildfire, without considering the other potential risks at the same time. Urban water systems are very interconnected; change to one part of the system will have a ripple effect across the whole system. We need to look at this more holistically, in terms of a range of water-related climate risks.

If you're only trying to solve the wildfire problem, you'd say we need more flows to fight fires. So you'd need bigger pipes and more storage. But designing water systems to fight these kinds of fires would be incredibly costly. And installing larger pipes for larger flows, under normal conditions, can lead to the water staying in the pipes for longer, which leads to water quality challenges. And water systems need to protect public health by providing safe drinking water.

With climate change, we also expect longer and more intense droughts. So if, on the flip side, you only solve the problem of drought, the solution is to use a lot less water. In that case, our current system is overdesigned, and we should redesign it so that pipes are smaller and there's less water in the system. Designing urban water systems to fight large, intense fires and designing them for droughts would address two clear and present risks in our state, yet the solutions are diametrically opposed.

So we have to rethink our problem statement. Maybe we do need to reconsider our standards and codes, but we can never fully eliminate risk. We must decide on an acceptable level of risk. We have to think about how we prepare for and respond to wildfires. That includes vegetation management, especially in the wildland-urban interface, and emergency response strategies. The water system plays an important part in that, but redesigning that system may not be the only solution.

We need to engage other players, including Cal Fire and other stakeholders. We need to be more creative and recognize that every system is unique-there will not be a one-size fits all solution. Some communities are at higher risk for climate challenges, and investments may look different in each community.

What gives you hope?

Every time that we tackle a big issue, we come back stronger and more prepared for the future. I have witnessed agencies come together on an issue like drought and get proactive to develop plans for greater resilience. We're recognizing that we need to do things differently-but we can't do them alone. We've got a ways to go, but we're trying to figure out how to introduce wildfire into a broader problem statement around climate resilience and how we solve for it.

Recognizing the interconnectedness of the system and bringing new partners and stakeholders into the mix with new ideas gives me hope that we'll work together and come up with better solutions.