225-2 Challenges and Opportunities Involved with Post-Wildfire Water-Quality Monitoring Across the western United States.

Session: Critical Zone Science: Intersection of Processes Linked to Geomorphology, Ecology, Fire and Climate (Posters)

Poster Booth No.: 221

Presenting Author:

Cara Peterman-Phipps

Authors:

Peterman-Phipps, Cara L.¹, Murphy, Sheila², Sleeter, Rachel³, McCleskey, Richard Blaine⁴, Clark, Gregory Daniel⁵, Elliott, Sarah M⁶, Blake, Johanna M.⁷, Payne, Sean⁸, Carpenter, Kurt D⁹, Alpers, Charles N.¹⁰, Ebel, Brian A¹¹

(1) U.S. Geological Survey, Westminster, MA, USA, (2) U.S. Geological Survey, Boulder, CO, USA, (3) U.S. Geological Survey, Gig Harbor, WA, USA, (4) U.S. Geological Survey, Boulder, CO, USA, (5) U.S. Geological Survey, Helena, MT, USA, (6) U.S. Geological Survey, Mounds View, MN, USA, (7) U.S. Geological Survey, Albuquerque, NM, USA, (8) U.S. Geological Survey, Portand, OR, USA, (9) U.S. Geological Survey, Portland, OR, USA, (10) US Geological Survey CAWSC, Davis, CA, USA, (11) U.S. Geological Survey, Lakewood, CO, USA,

Abstract:

Wildfires can result in tremendous changes in land cover and increase the availability of erodible soil and ash. Post-wildfire storms may cause an increase in erosion and subsequent sedimentation in waterways. Potential changes to water quality and quantity can make it difficult for water providers to treat and manage public water supplies. There is a growing need for consistent approaches to post-wildfire water-quality monitoring to collect representative data that can be compared across watersheds with the intent to assist resource managers in understanding potential wildfire impacts. However, there is substantial variability in land cover, geology, topography, and ecosystems across the western United States (U.S.) that, in turn, can lead to regional disparities in post-wildfire water-quality responses. Starting in 2021 the U.S. Geological Survey has been implementing a multi-watershed study across varying topographies and ecosystems by instrumenting 12 burned watersheds in the western U.S. We developed a strategic post-wildfire methodology combining discrete water-quality samples across the hydrologic spectrum along with continuous data for water quality and quantity (discharge). Constituents analyzed in discrete samples included suspended sediment, various forms of nitrogen and phosphorus, major cations and anions, dissolved organic carbon, ultraviolet absorbance at 254 nm, and stable isotopes of hydrogen and oxygen. Continuous data were collected for turbidity, water temperature, pH, specific conductance, dissolved oxygen, and fluorescent dissolved organic matter. This methodology was applied across the study watersheds and has generated consistent, unified post-wildfire water-quality datasets across the western U.S.   These harmonized datasets, in conjunction with remote-sensing analyses, are being used to explore hypotheses to explain regional variations in post-wildfire water-quality responses. We developed a conceptual framework to guide post-wildfire hypothesis development and testing that classifies environmental variables into four primary categories, Drivers-Factors-Stressors-Effects, that encompass identified and potential contributors and effects of post-wildfire regional variability. Ongoing research is translating post-wildfire water-quality data analysis and findings into assessments and modeling of key water-quality constituents across the western U.S., which has further increased this study’s effectiveness in analyzing post-wildfire watersheds.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7072

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