Drinking Water Under Fire

Abstract:

The U.S. is facing many issues related to climate change, with water scarcity being one of the most important. This challenge is compounded by the rising threat of wildfires that are growing in size and intensity. These wildfires threaten the drinking water watersheds for many Western U.S. cities, which rely on surface water as their water source. Wildfires cause a cascade of disturbances resulting from the removal of protective forest litter ground cover. One important change is that fire can create water repellent soil conditions that decrease water infiltration into soils causing an increase in erosion and flooding during post-fire rain events. The sediment, contaminants and debris that are washed downstream can reduce reservoir storage and clog intake pipes to water treatment facilities. Many drinking water filtration plants do not currently have sufficient equipment to handle the influx of sediment if a wildfire were to occur. To address the threat of wildfire to water quality issues, a four-pronged approach is needed:

1) Forest Management: Forests should be managed through mechanical and natural methods to reduce fuel loading. Selective thinning is effective and allows for some trees to stay and support regrowth. Prescribed fires are one of the best methods to restore ecosystems that naturally rely of wildfire.

2) Wildfire Suppression: Suppression of wildfires is important in watersheds that supply drinking water, and ground or hand crews are most effective.

3) Erosion Mitigation: Mitigation of soil erosion is critical after a wildfire. Straw mulch is a cost-effective treatment to apply since it provides immediate ground cover, which reducing the impact of rain, slows runoff and reduces erosion.

4) Water Treatment: The last line of defense, water treatment, is important to protect drinking water, for residents, after a wildfire.

These recommendations will allow water utilities to become more resilient to wildfires and their consequences which is a growing concern due to climate change.