OF-09-01 Geologic Hazards Mapping Project of the Uncompahgre River Valley Area, Montrose County, Colorado


The purpose of this mapping project is to improve Montrose County’s Mitigation Plan by identifying, describing, and analyzing the potential geologic hazards for private lands where development may occur in the future. The project area encompasses the Uncompahgre River valley and highlands to the east and west.

A 76-page report is included about the geologic hazards in the project area. This comprehensive report has chapters for all the geologic hazards listed above that includes an overview of the hazard, mapping methodology, and mapping results. For each potential hazard there are specific discussions of risk assessment and hazard vulnerability, mitigation strategies, and development considerations and recommendations for future land-use planning.

The map data includes GIS datasets at 1:24,000 scale and digital cartographic maps on 1:50,000-scale topographic basemaps that are in PDF format. The following datasets are included in this digital publication:

  1. The compiled 1:24,000-scale geologic map index of the project area
  2. Compiled inventory of all mapped landslides
  3. Landslide susceptibility map
  4. Rockfall hazard map
  5. Avalanche hazard map
  6. Debris/mud flow hazard map
  7. Swelling soil hazard rating map
  8. Collapsible soil susceptibility map
  9. Soil corrosion hazard map
  10. Digital scans of georeferenced FEMA Flood Insurance Rate Maps (FIRMs)
  11. Natural Resources Conservation Service (NRCS) flood hazard map
  12. Compiled earthquake and Quaternary fault map with HAZUS earthquake-scenario modeling results
  13. Poorly drained/salt pan area map
  14. Mancos Shale and susceptibility for selenium impairment map
  15. Slope classification map

This mapping and geologic hazard assessment project was funded by the Federal Emergency Management Administration (FEMA) (award number 6EM75C44) with matching funds by Montrose County and the CGS using the Colorado Department of Natural Resources Severance Tax Operational Funds. This project also benefited from concurrent STATEMAP geologic mapping in the Uncompahgre River valley. STATEMAP is funded jointly by the U.S. Geological Survey through the STATEMAP component of the National Cooperative Geologic Mapping Program that is authorized by the National Geologic Mapping Act of 1997 (award number 07HQAG0083), and the Colorado Geological Survey, using the Colorado Department of Natural Resources Severance Tax Operational Funds. CGS matching funds come from the severance tax paid on the production of natural gas, oil, coal, and metals. The geologic hazard maps were originally developed for the Montrose County government as deliverables for the FEMA grant award. OF-09-01D