Wildfires are devastating and can lead to long-term changes to the landscape. With a significant amount of our Nation’s drinking water sources originating in forested watersheds, evaluating the effect fires have on water quality is incredibly important. The USGS works with other federal and state land managers to assess water-quality after wildfires in order to help protect one of our most valuable resources.
BACKGROUND
Relatively new research has been aimed at the impacts of wildfires on the quality of drinking water and on water-dependent natural resources. In the last several decades, both the incidence of large wildfires and the duration of the wildfire season across much of the United States have increased. Approximately 80 percent of the U.S.'s freshwater resource originates on forested land, and more than 3,400 communities rely on public drinking-water systems located in watersheds on forest lands. Thus, the potential impacts from wildfire occurrence on the quantity and quality of runoff used for source water and to support fisheries and aquatic habitats are considerable. For example, water providers spent more than $26 million on water-quality treatment, sediment and debris removal, and related issues after two recent wildfires in Colorado.1
SOURCE WATER
Wildfire affects many facets of the source-water delivery system, ranging from immediate effects during a fire to long-term alteration of watersheds. During a fire, interruption of electrical power and access to water treatment plants, ambient water-quality monitoring equipment, and stream diversion and monitoring locations are common. Because existing water quality cannot be adequately determined, source-water suppliers are often forced to shift to stored water or other secondary water supplies. These sources tend to be of lower quality, which can necessitate increased pre-treatment actions and processes at considerable additional cost. Runoff from burned areas contains ash, which may have significant effects on the chemistry of receiving waters such as lakes, wetlands, reservoirs, rivers and. Runoff from burned areas also produces higher nitrate, organic carbon, and sediment levels, warmer temperatures, and flashier streamflows.
IMPLICATIONS FOR DRINKING-WATER TREATMENT
Drinking-water utilities strive to provide safe drinking water for their communities. Unfortunately, the unpredictable nature of wildfire makes it challenging to develop treatment-plant-specific strategies for treating source water degraded by the effects of wildfire. High-intensity rainfall events in steep, burned watersheds are likely to move large amounts of suspended and dissolved material into downstream water supplies. 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
A FUTURE OF CLIMATE EXTREMES
Wildfires are some of the world’s most deadly and expensive hazards. These events are incredibly distructive and are predicted to become bigger and more common in the future as extreme climate events become more frequent. Despite their critical importance, wildfires and their impacts on watersheds are challenging to study due to their unpredictability, the extensive damage they cause, and a lack of pre-existing information to which the response can be compared. What is know about them is they alter the surface soils, decrease infiltration during thunderstorms, and accelerate the movement of water, sediment, and debris from the landscape to nearby streams. This has a definitive impact on downstream water quality.
RELATED USGS RESEARCH
The USGS monitors water-quality and sediment characteristics in rivers and reservoirs affected by fires. These data helps scientists and water managers evaluate the cumulative effects of fire, and potential water-quality impacts on drinking-water supplies. Years after a wildfire, high-intensity storms can affect water quality. Monitoring source water downstream of burned watersheds allows water managers to minimize adverse effects on drinking-water quality, such as by temporarily diverting compromised water or changing source water.
- Monitoring the Impacts of Fire on Water Quality (USGS CA)
- Water Quality after a Wildfire (USGS CA)
ADDITIONAL RESOURCES
- Water Quality Impacts of Forest Fires (U.S. Forest Service)
- The Legacy of Severe Wildfire on Stream Water Quality (U.S. Forest Service)
- Wildfire and the Future of Water Supply (American Chemical Society)
- How Wildfires Contaminate Drinking Water Sources (University of Colorado)
- Effects of Wildfire on Drinking Water Utilities (City of Bend, OR)
Wildfires are devastating, but the impacts don't end when the fire is out. Long-term issues often arise, including impairment of sourcewaters. Here are a few related projects that look at water quality after wildfire.
Connections between Forested and Urban Landscapes and Implications for Water Supply
Economics of Wildland Fire
The Wildfire Research (WiRē) Team
Postwildfire Debris-Flow Hazards
- Overview
Wildfires are devastating and can lead to long-term changes to the landscape. With a significant amount of our Nation’s drinking water sources originating in forested watersheds, evaluating the effect fires have on water quality is incredibly important. The USGS works with other federal and state land managers to assess water-quality after wildfires in order to help protect one of our most valuable resources.
BACKGROUND
Relatively new research has been aimed at the impacts of wildfires on the quality of drinking water and on water-dependent natural resources. In the last several decades, both the incidence of large wildfires and the duration of the wildfire season across much of the United States have increased. Approximately 80 percent of the U.S.'s freshwater resource originates on forested land, and more than 3,400 communities rely on public drinking-water systems located in watersheds on forest lands. Thus, the potential impacts from wildfire occurrence on the quantity and quality of runoff used for source water and to support fisheries and aquatic habitats are considerable. For example, water providers spent more than $26 million on water-quality treatment, sediment and debris removal, and related issues after two recent wildfires in Colorado.1
Sources/Usage: Public Domain.Pre- and post-fire measurements of fire effects help ecologists, fire scientists, and managers determine how the severity of wildfires affects plants, animal habitat, and ecosystem services. (Credit: Rachel Loehman) SOURCE WATER
Wildfire affects many facets of the source-water delivery system, ranging from immediate effects during a fire to long-term alteration of watersheds. During a fire, interruption of electrical power and access to water treatment plants, ambient water-quality monitoring equipment, and stream diversion and monitoring locations are common. Because existing water quality cannot be adequately determined, source-water suppliers are often forced to shift to stored water or other secondary water supplies. These sources tend to be of lower quality, which can necessitate increased pre-treatment actions and processes at considerable additional cost. Runoff from burned areas contains ash, which may have significant effects on the chemistry of receiving waters such as lakes, wetlands, reservoirs, rivers and. Runoff from burned areas also produces higher nitrate, organic carbon, and sediment levels, warmer temperatures, and flashier streamflows.
IMPLICATIONS FOR DRINKING-WATER TREATMENT
Drinking-water utilities strive to provide safe drinking water for their communities. Unfortunately, the unpredictable nature of wildfire makes it challenging to develop treatment-plant-specific strategies for treating source water degraded by the effects of wildfire. High-intensity rainfall events in steep, burned watersheds are likely to move large amounts of suspended and dissolved material into downstream water supplies. 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
A FUTURE OF CLIMATE EXTREMES
Wildfires are some of the world’s most deadly and expensive hazards. These events are incredibly distructive and are predicted to become bigger and more common in the future as extreme climate events become more frequent. Despite their critical importance, wildfires and their impacts on watersheds are challenging to study due to their unpredictability, the extensive damage they cause, and a lack of pre-existing information to which the response can be compared. What is know about them is they alter the surface soils, decrease infiltration during thunderstorms, and accelerate the movement of water, sediment, and debris from the landscape to nearby streams. This has a definitive impact on downstream water quality.
RELATED USGS RESEARCH
The USGS monitors water-quality and sediment characteristics in rivers and reservoirs affected by fires. These data helps scientists and water managers evaluate the cumulative effects of fire, and potential water-quality impacts on drinking-water supplies. Years after a wildfire, high-intensity storms can affect water quality. Monitoring source water downstream of burned watersheds allows water managers to minimize adverse effects on drinking-water quality, such as by temporarily diverting compromised water or changing source water.
- Monitoring the Impacts of Fire on Water Quality (USGS CA)
- Water Quality after a Wildfire (USGS CA)
ADDITIONAL RESOURCES
- Water Quality Impacts of Forest Fires (U.S. Forest Service)
- The Legacy of Severe Wildfire on Stream Water Quality (U.S. Forest Service)
- Wildfire and the Future of Water Supply (American Chemical Society)
- How Wildfires Contaminate Drinking Water Sources (University of Colorado)
- Effects of Wildfire on Drinking Water Utilities (City of Bend, OR)
- Science
Wildfires are devastating, but the impacts don't end when the fire is out. Long-term issues often arise, including impairment of sourcewaters. Here are a few related projects that look at water quality after wildfire.
Connections between Forested and Urban Landscapes and Implications for Water Supply
Interactions between forested and urban landscapes can lead to reciprocal effects that have substantial impacts on water supply and ecology. Air pollution from urban and forested landscapes can be deposited on adjacent forests, while forest disturbance, such as wildfires and floods, can remobilize those contaminants. Additionally, pollutants from legacy land use (e.g., mining) can also be...Economics of Wildland Fire
In recent decades, wildfires have increased in size and intensity, and the fire season has lengthened. This and other factors have increased wildfire suppression costs and risks to human health and safety. SEA economists investigate numerous aspects of wildland fire, its impacts, and how to mitigate the risk wildfire poses to people, resources, and property.The Wildfire Research (WiRē) Team
Wildfires cost billions of dollars to suppress annually, yet they still devastate lives, communities, and ecosystems. While wildfire is a natural phenomenon, learning to live with wildfire is a social issue – so we need a social solution.Postwildfire Debris-Flow Hazards
Wildfire is a natural process in forest ecosystems, and occurs with varying frequencies and severities depending on landscape characteristics, climatic conditions, and the historical fire regime. Although attention often is focused on the potential damages from wildfire in the wildland-urban interface, wildfire also presents a threat to critical infrastructure including flood water conveyances and... - Publications
- News