A parched preceding year paired with exceptionally hot summer months set California up for a disastrous and historic 2018 fire season. So far in 2018, Cal Fire has recorded over 876,400 acres burned. That’s more than four times the acreage burned compared to this time last year, which Cal Fire reported as just over 228,800 acres.
It is obvious that these fires are a threat to people, wildlife, structures, and our heroic firefighters, but what is less obvious is the danger they pose to our water quality.
California’s forests supply more than 60 percent of the State’s water. According to the United States Geological Survey (USGS), “wildfires can compromise water quality both during active burning and for months and years after the fire has been contained.” While the fire is raging, ash can settle on lakes and reservoirs used for drinking water supplies. But even after the fire is extinguished, storms can further contaminate water supplies as burn areas easily erode and wash large amounts of sediment into streams, rivers, and reservoirs. This puts watersheds at greater risk of flooding and erosion.
The effects on water quality are both short- and long-term, as wildfires increase the costs associated with water treatment and the need for alternative supplies, and diminish reservoir capacity. According to USGS, potential effects of wildfire on municipal water supplies and downstream aquatic ecosystems include the following:
- Changes in the magnitude and timing of snowmelt runoff, which influence filling of water-supply reservoirs
- Increased sediment loading of water-supply reservoirs, shortened reservoir lifetime, and increased maintenance costs
- Increased loading of streams with nutrients, dissolved organic carbon, major ions, and metals
- Post-fire erosion and transport of sediment and debris to downstream water-treatment plants, water-supply reservoirs, and aquatic ecosystems
- Increased turbidity (cloudiness caused by suspended material), or heightened iron and manganese concentrations, which may increase chemical treatment requirements and produce larger volumes of sludge, both of which would raise operating costs
- Changes in source-water chemistry that can alter drinking-water treatment
In short, wildfires—past, present, and future—have a significant impact on the quantity and quality of runoff water, which affects domestic, agricultural, and ecological water supplies.
To make matters worse, experts say California wildfire frequency could surge 50% by 2050. This finding comes from California’s 4th Climate Change Assessment report, a collaborative effort among the Governor’s Office of Planning and Research, the California Natural Resources Agency, and the State’s Energy Commission. Intensified water quality challenges are amid the many problems this exceptionally bleak forecast poses for the future of California.