Effects of wildfire on benthic macroinvertebrate assemblages in Southern California streams and implications for bioassessment monitoring programs

California State Water Resources Control Board (SWRCB) | June 13th, 2012

Wildfires are common in arid regions of southern California, sometimes burning as much as half a million acres in a season. These fires often cause dramatic impacts to th

Wildfires are common in arid regions of southern California, sometimes burning as much as half a million acres in a season. These fires often cause dramatic impacts to the vegetation and soils of regional watersheds and, consequently, to the streams that drain them. Water quality programs that monitor and regulate these systems have to account for the influence of these factors upon water quality measurements when making monitoring and regulatory decisions. This is true for traditional water quality measures (nutrients, metals, contaminants, etc.), but is especially important for integrative ecological condition indicators like bioassessment, the use of resident biological communities to infer water quality condition.

Escalating Hydrological Extremes and Whiplashes in the Western U.S.: Challenges for Water Management and Frontline Communities

American Geophysical Union (AGU) | May 14th, 2025

Fire and Water: Assessing Drinking Water Contamination After a Major Wildfire

American Chemical Society (ACS) | August 2nd, 2021

We investigated patterns of volatile organic compound (VOC) contamination in drinking water systems affected by the California 2018 Camp Fire. We performed spatial analys

We investigated patterns of volatile organic compound (VOC) contamination in drinking water systems affected by the California 2018 Camp Fire. We performed spatial analysis of over 5000 water samples collected over a 17 month period by a local water utility, sampled tap water for VOCs in approximately 10% (N = 136) of standing homes, and conducted additional nontargeted chemical analysis of 10 samples. Benzene contamination was present in 29% of service connections to destroyed structures and 2% of service connections to standing homes. A spatial pattern was apparent. Tap water in standing homes 11 months after the fire contained low concentrations of benzene in 1% of samples, but methylene chloride was present in 19% of samples, including several above regulatory limits. Elevated methylene chloride was associated with greater distance from the water meter to the tap, longer stagnation time, and the presence of a destroyed structure on the service connection; it was inversely associated with certain trihalomethanes. Nontargeted analysis identified multiple combustion byproducts in the water at 2/10 homes. Our findings support the hypothesis that pyrolysis and smoke intrusion from depressurization contributed to the benzene contamination. Further research is needed to test the hypothesis that methylene chloride may be generated from the dehalogenation of disinfection byproducts stagnating in galvanized iron pipes.

Fire influence on land–water interactions in aridland catchments

Oxford University Press (OUP) | January 9th, 2025

Wildfires have increased in size, frequency, and intensity in arid regions of the western United States because of human activity, changing land use, and rising temperatu

Wildfires have increased in size, frequency, and intensity in arid regions of the western United States because of human activity, changing land use, and rising temperature. Fire can degrade water quality, reshape aquatic habitat, and increase the risk of high discharge and erosion. Drawing from patterns in montane dry forest, chaparral, and desert ecosystems, we developed a conceptual framework describing how interactions and feedbacks among material accumulation, combustion of fuels, and hydrologic transport influence the effects of fire on streams. Accumulation and flammability of fuels shift in opposition along gradients of aridity, influencing the materials available for transport. Hydrologic transport of combustion products and materials accumulated after fire can propagate the effects of fire to unburned stream–riparian corridors, and episodic precipitation characteristic of arid lands can cause lags, spatial heterogeneity, and feedbacks in response. Resolving uncertainty in fire effects on arid catchments will require monitoring across hydroclimatic gradients and episodic precipitation.

Growing human-induced climate change fingerprint in regional weekly fire extremes

Nature Portfolio (Springer Nature) | April 23rd, 2025

Increasing Hydroclimatic Whiplash Can Amplify Wildfire Risk in a Warming Climate

Global Change Biology (Wiley) | February 7th, 2025

The catastrophic January 2025 fires were propelled by an especially extreme combination of these two recognized risk factors: (1) downslope wind gusts over 80 mph (35 m/s

The catastrophic January 2025 fires were propelled by an especially extreme combination of these two recognized risk factors: (1) downslope wind gusts over 80 mph (35 m/s) and exceptionally dry vegetation following a historically dry start to the rainy season and unusually warm antecedent temperatures driving a prolonged episode of elevated atmospheric evaporative demand. But there was also a third contributor: two consecutive anomalously wet winters (in 2022–2023 and 2023–2024), which led to abundant growth of herbaceous vegetation across CSC. This remarkable wet-to-dry sequence, therefore, set the stage for the CSC wildfire disasters to unfold by first facilitating prodigious fuel accumulation during the previous growing seasons, then subsequently drying vegetation to produce exceptional flammability unusually far into winter (when Santa Ana winds are common). Globally, climate change has increased wildfire potential primarily through greater aridity (Jain et al. 2022). In CSC, hotter summer and autumn seasons drive this aridity by increasing evaporative demand (i.e., atmospheric “thirst”), subsequently drying out vegetation. This, in conjunction with an increasingly delayed onset of the rainy season (Goss et al. 2020), may also be increasing temporal overlap between critically dry vegetation and Santa Ana winds (Swain 2021). As the events of January 2025 vividly illustrate, however, transitions from anomalously wet to anomalously dry conditions may further amplify these risks by exacerbating fuel accumulation and desiccation cycles. Indeed, in fire regimes (including CSC) where fire occurrence varies strongly with inter-annual variations in biomass (Swetnam et al. 2016), increased hydroclimate volatility is causally linked to increased wildfire activity.

Metals in Wildfire Suppressants

American Chemical Society (ACS) | October 30th, 2024

Organic Chemical Contaminants in Water System Infrastructure Following Wildfire

American Chemical Society (ACS) | February 1st, 2022

Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile o

Wildfires have destroyed multiple residential communities in California in recent years. After fires in 2017 and 2018, high concentrations of benzene and other volatile organic compounds (VOCs) were found in public drinking water systems in fire-affected areas. The sources of the contamination and appropriate remediation have been urgent matters of investigation. This study characterizes target and nontarget VOCs and semivolatile organic compounds (SVOCs) in water from a highly contaminated service line after the 2018 Camp Fire (Paradise, CA). Ninety-five organic compounds were identified or tentatively identified in the service line. Laboratory combustion experiments with drinking water pipes made of polyvinyl chloride (PVC), cross-linked polyethylene, and high-density polyethylene and a review of the literature were used to evaluate potential sources of the detected chemicals. Among the service line contaminants were 32 compounds associated with PVC pyrolysis and 28 organic compounds also associated with the pyrolysis of polyethylene. The service line sample also contained 55 compounds associated with uncontrolled burning of biomass and waste materials. The findings support hypotheses that wildfires can contaminate drinking water systems both by thermal damage to plastic pipes and intrusion of smoke. Residual chlorine disinfectants in the water system modify the contaminant distribution observed.

Post-fire evapotranspiration estimates in ground truth limited environments

Elsevier | June 16th, 2025

Wildfires are catastrophic events with increasing incidence and severity, especially in Mediterranean climates like California. Wildfires can drastically change the hydro

Wildfires are catastrophic events with increasing incidence and severity, especially in Mediterranean climates like California. Wildfires can drastically change the hydrologic components of a watershed and require consistent and reliable data to monitor recovery. With the upcoming retirement of the Moderate Resolution Imaging Spectroradiometer (MODIS), a reliable evapotranspiration (ET) product at the subcatchment scale is necessary to monitor longitudinal ET, particularly post-fire. We evaluate NASA JPL's ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS), MODIS, and the North American Land Data Assimilation System phase 2 (NLDAS-2) to assess performance in longitudinal evapotranspiration (ET) estimates and post-fire ET change detection using correlation analysis and linear regression for twelve subwatersheds located within the August Complex Fire (August 2020) in Trinity County, the Delta Fire (September 2018) in Shasta and Trinity Counties, and the Creek Fire (September 2020) in Fresno County for a four-year period. We found that MODIS and ECOSTRESS showed the strongest correlation in daily ET estimates (mean r = 0.56), while correlations between ECOSTRESS-NLDAS-2 (r = 0.06) and MODIS-NLDAS-2 (r = 0.30) were notably weaker. However, ECOSTRESS data availability constrained post-fire change detection and annual ET sum assessments. Its higher spatial resolution and correlation with MODIS have potential for finer-scale model parameterization of post-fire landcover changes, particularly vegetation loss in place of MODIS. NLDAS-2 can be useful in monthly and annual patterns at larger scales. By comparing ECOSTRESS with established platforms of ET estimation, we validate ECOSTRESS as a tool for post-fire ET monitoring, especially in areas where ground truth data is unavailable. These findings can allow for more informed and effective land management decisions, particularly in wildfire and vegetation monitoring.

Post‐Fire Sediment Yield from a Western Sierra Nevada Watershed Burned by the 2021 Caldor Fire

American Geophysical Union (AGU) | January 7th, 2025