Committee Spotlight: Stormwater

Wildfires, Safety, and Water Quality: After the Smoke Clears
By Allison Lukens, EI, Mead & Hunt, Inc.

If you live in the Western part of the United States, chances are you were impacted by the historic wildfire season in 2020. A total of 10.27 million acres and nearly 59,000 fires burned last year, contributing to the largest annual wildfire acreage burned in the U.S. since 1960. Although it’s difficult to predict the precise time, location, and magnitude of wildfires, we need to accept that they are a possibility and do whatever we can to prepare for them. 

For municipalities and utilities, the top priority during a fire event, of course, is the personal safety of your staff and community. Staying current is essential, because once a fire starts, conditions can change rapidly. This National Wildfire Coordinating Group interactive map shows current and real-time data on the fire potential in your area. If you work for a municipality or utility, be sure to enroll your organization in WARN or other mutual aid programs, which allow your local government or utility to provide other communities with assistance when they need it, as well as receive assistance from other communities when you need it.

We all know the ways wildfires impact human health and property, but they can also impact our water quality. The immediate and long-term water quality effects of wildfires are not fully understood yet, but we do know that a wildfire that burns for a short time can impact water quality for years afterward. Burned areas once densely vegetated may be susceptible to increased erosion and runoff. Sediment loads, including large limbs from fallen trees, increase after burning when ash and contaminants settle into surface waters. Solids, nutrients, metals, fire retardants, and other fire-fighting chemicals can accumulate after wildfires, especially after subsequent rainfall events. In the first year after a wildfire, we can expect to see initial increases in dissolved organic carbon, dissolved organic nitrogen, and ammonium. In subsequent years, nitrate concentrations may increase. These long-term water quality impacts may be mitigated by reestablishing vegetation in denuded areas as soon as possible, even with a temporary cover crop. 

For stormwater utilities, sediment and debris are a major concern as they can lead to storm sewer backup. Schedule cleanouts and other routine maintenance tasks prior to fire season to lower the risk of storm sewer overflows. Clearing storm drains, inlet protection devices, and other stormwater collection devices prior to wildfires will prevent overflows and allow stormwater treatment devices to operate effectively if contaminant levels begin to increase.

These contaminants can make their way into drinking water systems, too. Dissolved organics released from wildfires can contribute to disinfection by-products, including trihalomethanes and haloacetic acids. A post-fire protocol may be necessary to overcome treatment challenges related to wildfires, like this one, which includes expanding turbidity monitoring in the field and setting up sediment traps upstream of intake structures. Incorporating an alternative groundwater source while surface water treatment operations are adjusted post-fire could help prevent service disruptions, like the Bull Run Filtration Facility that is under construction in Portland, Oregon. 
water treatment

Wildfires are overwhelming, but there are steps we can take to prepare for them, protect our drinking water sources, and reduce potential water quality impacts. Focus on the following key takeaways:

  • Always stay current on wildfire news, and keep staff and community safety as your top priority.
  • For stormwater management facilities, prioritize revegetation of denuded areas immediately, and perform maintenance tasks prior to the start of fire season to protect water quality.
  • For drinking water facilities, develop a post-fire protocol, and consider treatment methods that aid in reducing turbidity in water supply. Focus on monitoring turbidity upstream, and watch for potential increases in disinfection by-product levels.

While wildfires can be unpredictable, focusing on what we can control offers a way to protect and preserve the health of our communities.

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