After wildfires, scorched trees could disrupt water supplies

TWIN BRIDGES, Calif. – In a California forest torched by wildfire last summer, researcher Anne Nolin examines a handful of the season’s remaining snow, now darkened by black specks from the burned trees above.

Nolin and her colleague are studying the scorched trees, which no longer provide much shade and are shedding flecks of carbon.

The darkened snow is “primed to absorb all that sunlight” and melt faster, said Nolin, who researches snow at the University of Nevada, Reno.

As climate change fuels the spread of wildfires across the West, researchers want to know how the dual effect might disrupt water supplies. Communities often rely on melting snow in the spring to replenish reservoirs during drier months. If snow melts earlier than normal, that would likely leave less water flowing in the summer when it’s most needed, Nolin said.

Multiple studies indicate snow in a burned forest disappears up to several weeks sooner than snow in a healthy forest because of the lack of a shade canopy and carbon shedding from trees intensifying the absorption of sunlight.

Nolin and graduate student Arielle Koshkin hiked into the El Dorado National Forest for one of their final measuring trips earlier this month when the region typically has the most snow accumulation. Little remained when they arrived in part because of unusually hot temperatures this spring and a long streak of cloudless days.

Late-season storms have since blanketed the carbon-coated snow with several inches of fresh powder, which Nolin said could help slow the melt.

Meanwhile, the Caldor Fire that burned the area and more than 200,000 acres last year has left nearby communities scrambling over more immediate water worries.

About 40 miles southwest of where Nolin surveyed the snow, the town of Grizzly Flats is working to fix a water pipeline damaged in the fire that diverts snowmelt into a reservoir but burned trees keep falling and puncturing it.

It’s not yet clear exactly how the charred trees might disrupt their future water supply. So far this year, water managers said runoff from snowmelt appears normal. But officials don’t know for sure since the gauges in the stream melted in the fire.