Recent findings have illuminated concerning patterns in wildfire activities across the Western United States. An extensive study featured in the journal Nature scrutinized over 17,000 watersheds from 11 states, mapping fire occurrences since 1940. The investigation revealed notable changes in fire dynamics during the latter part of the 20th century, particularly in forested and mountainous regions that contribute significantly to water runoff.
Water sources catering to over 100,000 individuals have experienced a near doubling in the average annual area burned, rising from 4.7% to 9.1%, signaling a notable increase in fire impact. Alicia Kinoshita, a study author from San Diego State University, remarked, “What we were noticing that was alarming, I’d say, [is] that watersheds that were serving over 100,000 people nearly doubled in annual burn area.”
Significant Changes in Mountainous Regions
The most substantial increases were observed in mountainous territories, including Utah’s Wasatch and Uinta Mountains, and the southern Rockies. The Klamath Mountains, spanning California and Oregon, also experienced significant upticks in burned areas. Conversely, the Great Basin, primarily covering Nevada, showed stable or diminishing fire trends, likely due to its sparse vegetation.
These findings are crucial as much of the Western water supply originates from forested mountain watersheds, which provide over half of the region’s water and surface drinking water for approximately 83 million people. “After a fire, we usually see increased water quantity and decreased water quality, and that’s just because we usually see a removal of the vegetation and things that are kind of holding everything in place,” Kinoshita explained.
The repercussions of wildfires can lead to diminished water quality and complications for water systems, including reservoirs, dams, and treatment facilities. Issues such as post-fire flooding, sediment, and nutrient pollution can persist in challenging treatment processes for extended periods.
Challenges with Aging Infrastructure
The escalating wildfire hazard is compounded by aging water infrastructure. Much of this infrastructure was developed in the mid-20th century, predating the wildfire activity changes identified in the study. These systems were built with the expectation of consistent hydrologic conditions, which no longer hold true under current climate and wildfire pressures, alongside rising water demand.
Kinoshita emphasized the potential for the research to assist land and water managers in pinpointing areas where preventative measures are critical. “We’re really hoping [the study] highlights these vulnerabilities and these at-risk areas,” she noted. “And for managers, just kind of guiding, like, here are some hot spots that we think are really important, that could be at high risk.”
The study advocates for interventions such as prescribed burns, restoration of streamside vegetation, and enhanced real-time monitoring to mitigate these risks.
This article is a collaborative effort by the Mountain West News Bureau, partnering with various public media organizations and supported by the Corporation for Public Broadcasting and Eric and Wendy Schmidt.
