TONYA MOSLEY, HOST:
In many Western states, drinking water supplies start high up in the mountains as rivers. This summer's record-breaking wildfires have reduced some headwater forests to burn trees and heaps of ash. As Luke Runyon from member station KUNC reports, that often creates expensive headaches for water treatment plants long after the smoke clears.
LUKE RUNYON, BYLINE: Few places in the West know how wildfires affect water supplies like Fort Collins, Colo. The state's largest wildfire ever recorded is burning just outside the city now. But their problems really started eight years ago. Before then, its main water source, the Poudre River, was nearly pristine.
JILL OROPEZA: We had been privileged and in some ways probably took for granted that these watersheds were providing us consistently clean, clear water all the time.
RUNYON: That's Fort Collins water quality manager Jill Oropeza. We're along the river just outside the city, downstream from where, in 2012, the High Park Fire burned more than 87,000 acres. For the first year after the fire, every time it rained, the river turned black from mudslides.
OROPEZA: We ended up with a lot of sediment in our pipelines that was difficult to remove.
RUNYON: To keep those muddy flows from causing problems, the city installed an early warning system, a series of monitoring stations along the river. If there's too much sediment, Oropeza says utility workers can turn off the treatment plant's intake and switch to water from a large reservoir.
OROPEZA: It became really important for us to have a heads-up for when those changes in water quality were occurring.
RUNYON: The effects of the burn scar on water quality only lasted a few years. But this early warning system is far from obsolete because this year's Cameron Peak Fire has burned another broad sweep of the river's watershed, which means Fort Collins again joins the list of Western cities learning to live with wildfires that burn bigger and hotter than they've ever seen before.
JOE HARWOOD: This is a new reality, and we're learning as we go.
RUNYON: Joe Harwood is with the water and electrical utility for 200,000 people in and around Eugene, Ore. This summer, the Holiday Farm Fire burned along the banks of their sole water source, the McKenzie River. Soon after, their customers noticed the water coming out of their faucets had a smoky taste.
HARWOOD: People quite frankly, to use a scientific term, were freaked out 'cause it's not something that they'd dealt with before.
RUNYON: Harwood says they eventually figured out the chemistry at their treatment plant to remove the taste. And when this winter's rainstorms arrive, utility workers will be monitoring for other harmful things that can be transported in wildfire runoff, like nitrates, heavy metals and dissolved organic carbon.
HARWOOD: We're trying to learn the lessons of others - Colorado and California - to create our own best management practices.
RUNYON: The utility is spending $1 million this year on post-fire erosion control, with more spending planned next year, Harwood says.
Back on the banks of Colorado's Poudre River, the city of Fort Collins' Jill Oropeza says the city had to raise water rates to deal with effects of the fire eight years ago. That could happen again. But she says decisions the city made after that last big fire - like building new infrastructure to remove sediment and beefing up policies around residential water restrictions - will help them respond this time around.
OROPEZA: We live in fire-prone watersheds, and that is our - part of our responsibility to adapt to those - that reality.
RUNYON: A reality that, because of climate change, increasingly includes drier forests, hotter summers and extended fire seasons across the West.
For NPR News, I'm Luke Runyon in Fort Collins, Colo.
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