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National Snag Hazard (Image Service)

posted on 2024-06-05, 12:50 authored by U.S. Forest Service

Snags continue to pose an ever-present hazard to responders, and recent increases in fire activity have resulted in an accumulation of these hazards across forested landscapes of the American West. National Snag Hazard is intended to provide a landscape-level view of existing snag hazard to firefighters and other field going employees. National Snag hazard is based on estimated density and median height of snags greater than or equal to 7.9 inches in diameter at breast height. Snag density and median snag height are classified into hazard levels using the breakpoints from Dunn et al. 2019, which are based on the logic that hazard increases with snag density and height. Dunn CJ, O’Connor CD, Reilly MJ, Calkin DE, Thompson MP (2019) Spatial and temporal assessment of responder exposure to snag hazards in post-fire environments. Forest Ecology and Management 441, 202-2014. DOI:10.1016/j.foreco.2019.03.035 This is a strategic landscape level decision support tool intended to help firefighters consider the magnitude and spatial distribution of snag hazard in their incident response strategy planning. Valid uses include identifying areas of higher snag hazard locations on landscape that may require extra mitigation for safe operation or could be avoided to reduce risk to responders. The snag hazard map is not meant to identify individual dead trees or for tactical planning. A rating of low snag hazard does not mean that no overhead hazards are present and should not be interpreted as judgement that an area is safe to occupy. Conditions should always be verified in the field. High levels of awareness for overhead hazards are always recommended regardless of the snag hazard rating.

This record was taken from the USDA Enterprise Data Inventory that feeds into the catalog. Data for this record includes the following resources:
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Data contact name


Data contact email


U.S. Forest Service


  • Geospatial

Geographic Coverage


ISO Topic Category

  • environment

National Agricultural Library Thesaurus terms

Forestry, Wildland Management

OMB Bureau Code

  • 005:96 - Forest Service

OMB Program Code

  • 005:059 - Management Activities

Pending citation

  • No

Public Access Level

  • Public

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