Fire and water: The burn is out but our clean water remains under threat

At Oregon Forests Forever we’ve detailed the many negative impacts of wildfires. Here’s another one: Flooding and water pollution.

The U.S. Forest Service recently conducted a burned soil assessment for the Cougar Creek Fire in Washington. They found that the fire burned primarily within the Mad River watershed and communities downstream may be at risk.

Depending upon winter rains, The Wenatchee World Herald reports the area could see:

  • A flush of ash, erosion in drainages and steep slopes, flash floods, increased water and debris flows
  • Runoff may increase twofold. Pine Flat Campground and downstream private residences are at risk
  • Potato and Windy creeks areas are of particular concern

Then there’s the risk of water pollution in the aftermath of fire.

A paper recently published at the Yale School of Forestry & Environmental Studies examined how wildfires leave in their wake debris and toxic runoff that pollute rivers and foul water supplies. As wildfires become more frequent and destructive, these effects will grow worse.

In June 2018, residents, tourists and park officials witnessed the usually cold and clear Cameron Falls in Canada’s Waterton Lakes National Park suddenly run pitch black. Heavy rains had flushed in soot, ash and charred tree debris from a fire that burned most of the 195-square-mile park the year before.

It happened again a few weeks later after another heavy rainstorm.

This pollution can impact far more than just nearby cities.

“Forests yield 40 percent of the water for the world’s 100 largest cities,” said Deborah Martin in the paper, a Colorado-based U.S. Geological Survey scientist. “Many of these cities are already water-stressed because of drought, climate change, and increasing water consumption. The increase in wildfire activity could make it much worse.”

In Colorado, the Hayman Fire burned 138,000 acres across four counties in 2002, removing many of the trees from parts of the mountain landscape. Hot drought conditions then baked the exposed soil. Some spring-fed streams stopped flowing and chemical compounds that were vaporized by the fire were driven into the soil, forming a layer below the surface.

Heavy rains that followed flushed tons of ash, debris, heavy metals and nutrients throughout the watershed, with no trees, vegetation or stable soil to absorb them. The blue-ribbon South Platte River trout fishery saw a precipitous decline, as did the water quality for 75 percent of the state’s residents.

Find the rest of the Yale paper here to learn more about pollution from wildfires.

Sign up to stay informed on all things Oregon forests