Montana State research to help communities prepare for wildfire impacts to municipal water

BOZEMAN — Even after the smoke clears, communities can be impacted by wildfire when scorched mountainsides are flushed with rain, washing sediment, ash and other contaminants into streams and reservoirs that supply drinking water.

In light of the severity and frequency of wildfires across much of the U.S., a Montana State University researcher and collaborators are working to help communities better safeguard water resources against wildfires as part of a three-year, $4 million transdisciplinary project led by the U.S. Forest Service Pacific Northwest Research Station.

“We want to provide municipalities and others in the drinking water community with really clear, science-based guidance for how they can invest their money and resources to prepare for future wildfires,” said Amanda Hohner, assistant professor in the Department of Civil Engineering in MSU’s Norm Asbjornson College of Engineering.

Hohner, a drinking water treatment engineer, will use $725,000 of the funding for research focused on understanding the water infrastructure and treatment processes currently used by communities, how those systems may be vulnerable to potential wildfire impacts and what changes water managers could make to be better prepared.

In collaboration with Hohner, other partners, including researchers at Oregon State and Washington State universities, will conduct field studies to monitor burned headwaters and understand how recent fires have affected watersheds in the Pacific Northwest and develop models showing how future wildfires could affect municipal water supplies. The project includes a socioeconomic analysis of the costs of wildfires to community water supplies and the investments that are most likely to pay off in the future. The research results will be widely applicable to Montana, where many communities rely on surface water supplies in forested watersheds that are vulnerable to fire, Hohner said.

“This is a collaborative effort involving a wide range of expertise to tackle a complex topic,” said Hohner, noting that the team includes hydrologists, foresters, ecologists and environmental economists at the partnering institutions. “It’s exciting to be working with a team of researchers with diverse backgrounds and expertise to address this problem.”

Since the project kicked off last spring, the team hosted a virtual workshop with stakeholders involved in watershed and drinking water management. “We really want to engage stakeholders, including municipalities and state and federal agencies, so that our work is aimed at addressing the challenges they face,” she said.

The motivation for the project came in the wake of the 2020 wildfire season that saw fires rage across the Pacific Northwest, with many cities and towns experiencing problems with drinking water supplies afterward. Fires consume vegetation that anchors soil and helps the ground absorb rain and snow. The absence of that vegetation leads to more rapid runoff filled with sediment and debris as well as ash and charcoal. Because most municipal water systems aren’t designed to handle extreme post-fire runoff and erosion, the large flush of sediment and debris can damage and clog water intake pipes and overwhelm treatment processes and filtration systems that normally remove smaller quantities of sediment and contaminants, according to Hohner.

In her MSU lab, Hohner will test different water treatment processes using samples collected from surface waters impacted by wildfires to assess which technologies are most effective at removing the fine ash and organic carbon that commonly spike in concentration after a rainstorm hits a burned area. The funding will provide opportunities for several undergraduate and graduate students to be involved in the work, Hohner said.

Combined with the work of the rest of the team, Hohner’s research will result in specific and comprehensive recommendations for how water managers could upgrade infrastructure to better manage future wildfire risk, she said. That could include adding different treatment technologies, adjusting daily operations schedules and expanding filter systems to better handle sediment and ash runoff. Additionally, the research is exploring how different types of water supplies are affected and the benefits of diversifying water sources to include groundwater, reservoirs and watersheds not as prone to wildfires, as well as adding capacity and flexibility to the system through water storage and other infrastructure.

Bozeman and Helena are among the communities in the state that source their municipal water from streams in forested areas that could burn, she noted. Because many other, smaller towns may not have the resources to invest in water system upgrades, one goal of the project is to help quantify the kind of assistance those communities may need from federal agencies and other partners.

“Unfortunately, the wildfire problem isn’t going away anytime soon,” Hohner said. “This research is one part of helping provide communities resources to be more resilient.”