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National Snag Hazard 2026 (Image Service)

Published by U.S. Forest Service | Department of Agriculture | Catalog Last Checked: August 01, 2026 at 05:00 AM | Dataset Last Updated: March 30, 2026
Snags are a hazard to firefighters that has traditionally been managed at the field level through scouting, rapid assessment, and mitigation by avoidance or by elimination though felling. Widespread wildfires and insect/disease disturbances have resulted in an accumulation of snags across many forested landscapes, raising the risk of injury or death for firefighters and other forest workers. The National Snag Hazard Map (Riley et al. 2022) is intended to provide a landscape level view of current snag hazard to encourage awareness, assessment, and planning to mitigate snag-related risks. The National Snag Hazard Map is based on the estimated density and median height of snags greater than or equal to 7.9-in diameter at breast height and at least 10-ft tall. Snag density and median snag height are classified into hazard levels based on the logic that hazard increases with snag density and height (Dunn et al. 2019). Snag hazard is a 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 on the landscape that may require extra mitigation for safe operation, or that could be avoided to reduce risk to firefighters. The snag hazard map is not meant 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. Maintaining high situational awareness for overhead hazards is recommended regardless of the snag hazard rating.  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 Riley KL, O’Connor CD, Dunn CJ, Haas JR, Stratton RD, Gannon B (2022) A national map of snag hazard to reduce risk to wildland fire responders. Forests 13, 1160. DOI:10.3390/f13081160

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Complete Metadata
@type dcat:Dataset
accessLevel public
bureauCode 
[
  "005:96"
]
contactPoint 
{
  "fn": "USFSEnterpriseContent",
  "@type": "vcard:Contact",
  "hasEmail": "mailto:SM.FS.data@usda.gov"
}
description Snags are a hazard to firefighters that has traditionally been managed at the field level through scouting, rapid assessment, and mitigation by avoidance or by elimination though felling. Widespread wildfires and insect/disease disturbances have resulted in an accumulation of snags across many forested landscapes, raising the risk of injury or death for firefighters and other forest workers. The National Snag Hazard Map (Riley et al. 2022) is intended to provide a landscape level view of current snag hazard to encourage awareness, assessment, and planning to mitigate snag-related risks. The National Snag Hazard Map is based on the estimated density and median height of snags greater than or equal to 7.9-in diameter at breast height and at least 10-ft tall. Snag density and median snag height are classified into hazard levels based on the logic that hazard increases with snag density and height (Dunn et al. 2019). <div><br /></div><div>Snag hazard is a 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 on the landscape that may require extra mitigation for safe operation, or that could be avoided to reduce risk to firefighters. The snag hazard map is not meant 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. Maintaining high situational awareness for overhead hazards is recommended regardless of the snag hazard rating. </div><div><br /></div><div> 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 Riley KL, O’Connor CD, Dunn CJ, Haas JR, Stratton RD, Gannon B (2022) A national map of snag hazard to reduce risk to wildland fire responders. Forests 13, 1160. DOI:10.3390/f13081160</div>
distribution 
[
  {
    "@type": "dcat:Distribution",
    "title": "ArcGIS Hub Dataset",
    "format": "Web Page",
    "accessURL": "https://data-usfs.hub.arcgis.com/datasets/usfs::national-snag-hazard-2026-image-service",
    "mediaType": "text/html"
  },
  {
    "@type": "dcat:Distribution",
    "title": "ArcGIS GeoService",
    "format": "ArcGIS GeoServices REST API",
    "accessURL": "https://imagery.geoplatform.gov/iipp/rest/services/Fire_Aviation/USFS_EDW_SAB_NationalSnagHazard/ImageServer",
    "mediaType": "application/json"
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  {
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identifier https://www.arcgis.com/home/item.html?id=cb4800493f7e4fb28722bcde05eee71c
issued 2023-05-11
keyword 
[
  "National",
  "Open Data",
  "Snag",
  "Snag Hazard",
  "USDA Forest Service",
  "USFS",
  "fire"
]
landingPage https://data-usfs.hub.arcgis.com/datasets/usfs::national-snag-hazard-2026-image-service
license https://creativecommons.org/licenses/by/4.0/
modified 2026-03-30
programCode 
[
  "005:059"
]
progressCode onGoing
publisher 
{
  "name": "U.S. Forest Service",
  "source": "U.S. Forest Service"
}
spatial -127.8583,23.2431,-65.3735,51.5427
theme 
[
  "geospatial"
]
title National Snag Hazard 2026 (Image Service)

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