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Wildfire’s Impact on Water Quality

26 Aug 2020 8:38 PM | Natalie Love (Administrator)

I know this topic is on everyone’s mind as you walk outside to see and smell the smokey wildfires burning around the state. With the devastation of wildfires burning precious land and polluting the air, comes the aftermath of the detrimental effects on water quality in the watershed. After the fire burns, vegetation is burned up leaving ash and nutrients to flow into the source water.

Immediate impacts may occur as soot and ash increase solids loading, adding to the possibility of destruction to source water infrastructure and alterations to the physical watershed. It’s the aftermath and long-term effects on the ecology of the fire scorched landscape that will be costly. Runoff from burned areas contain elevated nutrients like nitrogen and phosphorus with higher levels of organic carbon, turbidity, sediment and heavy metals which may have significant effects on the chemistry of the receiving water.  Higher nutrient loads from runoff could have an effect the on the water treatment process, which in turn, could create algae blooms in the storage reservoirs and lakes. Increases in organic carbon and turbidity will have a major impact on treatment abilities with higher chemical cost. Elevated carbon levels in raw water can result in higher total organic carbon (TOC) and turbidity in the distribution and result in higher disinfection byproduct (DBP) levels. Already low maximum contaminant levels (MCL) for DBPs, could cause non-compliance issues very easily with contaminated source water. There are also issues with pH adjustments and swings in alkalinity which need to be closely monitored in the water quality and treatment process.

Severe occurrences of heavy rainfall after a burn will cause mudslides, severe erosion and large debris running off into water delivery systems. These occurrences can make the water unusable or inaccessible, requiring a quick decision for switching to alternative water sources. Depending on the location of the fire, there also poses a threat of higher concentrations of contaminating heavy metals. In Colorado, there are possibilities of historic mining areas containing large amounts of iron, manganese, sulfates or even fire retardant that will runoff into the water. Even more severe is increased levels of naturally occurring mercury in the soil that could contaminate the source water and even elevate levels of mercury in native fish.

Be smart, prepared, and develop a plan to monitor when a wildfire occurs in your watershed. Some things to consider: What analytes are of concern, what locations are impacted, upstream comparison data, long term solutions, and how to prevent excessive nutrient ash runoff or mudslides with debris.

Now is the time to create an emergency plan or update a previous plan that suites your water system. Some ideas to think about when planning for the future:

-Put a plan in place to fund mitigation of wildfire destruction and spread. Support local forest services or the Unites States Forest Service (USFS) to help remove mountain pine beetle destroyed trees that act as fuel for these fires. They can also utilize GIS- based decision support tools which can manage sensitive areas and create buffer strips.

-Plan ways to adapt to problems with redundancy in infrastructure and alternative canals or source water. Consider adjustable intake locations for canals and reservoirs due to broken trees, debris, and sedimentation causing blockages at intakes. Create redundancy with surrounding cities water sources and water towers in case of disruption of service.

-Plan for increased water treatment cost in chemicals with elevated turbidity levels and sediment with more monitoring for water quality issues throughout the system. Have an internal troubleshooting guide.

-Review other utilities case studies on wildfire management occurrences and possible solutions.

If you are interested in preventing wildfire and water treatment, I recommend getting involved with the Watershed Wildfire Protection Group. They consist of a broad range of utilities and companies that have great ideas to solutions with a proactive stance of protecting watersheds from wildfires.

I don’t mean to bring up another harsh issue as we are all dealing with COVID effects but now is the time to make proactive plans, write grants for forest mitigation, and prepare for possible catastrophic events with climate change making these events even worse or more frequent. To end on a positive note….forest fires also help in the natural cycle of forest growth, replenishment, and help new plants grow!

John Winterton is the Laboratory Supervisor at the City of Northglenn.

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