Variable wildfire impacts on the seasonal water temperatures of western US streams: A retrospective study

PLoS One. 2022 Jul 20;17(7):e0268452. doi: 10.1371/journal.pone.0268452. eCollection 2022.

Abstract

Recent increases in the burn area and severity of wildfires in the western US have raised concerns about the impact on stream water temperature-a key determinant of cold-water fish habitats. However, the effect on seasonal water temperatures of concern, including winter and summer, are not fully understood. In this study, we assessed the impact of wildfire burns at Boulder Creek (Oregon), Elk Creek (Oregon), and Gibbon River (Wyoming) watersheds on the downstream winter and summer water temperatures for the first three post-fire years. To obtain results independent of the choice of the analytical method, we evaluated the consequence of each burn using three different statistical approaches that utilize local water temperature data. Our results from the three approaches indicated that the response of water temperatures to wildfire burns varied across seasons and sites. Wildfire burns were associated with a median increase of up to 0.56°C (Standard Error; S.E. < 0.23°C) in the summer mean water temperatures (MWT) and 62 degree-day Celsius (DDC; S.E. < 20.7 DDC) in the summer accumulated degree days (ADD) for the three subsequent years across studied stream sites. Interestingly, these burns also corresponded to a median decrease of up to 0.49°C (S.E. < 0.45°C) in the winter MWT and 39 DDC (S.E. < 40.5 DDC) in the winter ADD for the same period across sites. Wildfire effects on the downstream water temperatures diminished with increasing site distance from the burn perimeter. Our analyses demonstrated that analytical methods that utilize local watershed data could be applied to evaluate fire effects on downstream water temperatures.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Burns*
  • Retrospective Studies
  • Seasons
  • Temperature
  • Water
  • Wildfires*

Substances

  • Water

Grants and funding

The information in this document has been funded entirely by the U.S. Environmental Protection Agency (EPA), in part through appointments to the Internship/Research Participation Program at the Office of Research and Development, U.S. Environmental Protection Agency, administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the U.S. Department of Energy and EPA. Role of Funder/Sponsor: As an institution, the funder (U.S. EPA) had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.