OF-03-16 Critical Landslides of Colorado


This report includes a listing and ranking of Colorado’s most severe landslide hazards, in terms of past and potential future landslide activity and impacts. It contains a priority list of 47 areas of concern and is intended as a tool to direct statewide mitigation efforts. This is an updated version of the B-48 Colorado Landslide Hazard Mitigation Plan. 1 color plate (1:50,000). Digital PDF download. OF-03-16D

The Colorado Landslide Hazard Mitigation Plan was published in 1988 as Colorado Geological Survey Bulletin 48 (Jochim and others, 1988). It was written by authors from the CGS, the Colorado Division of Disaster Emergency Services (now Office of Emergency Management), and the University of Colorado Center for Community Development and Design. The plan was adopted by the state of Colorado and was cited for implementation, along with Flood Hazard and Wildfire Hazard plans, in the Governor’s 1989 Executive Order that created the Colorado Natural Hazards Mitigation Council (CNHMC). Until 1998, the CNHMC had a standing committee on Geologic Hazards and a subcommittee on Landslides.

One of the tasks done by CGS for Bulletin 48 was preparation of a list of Colorado’s communities, areas and facilities most at risk from landslides. That list consisted of 49 locations believed at that time to pose the most serious landslide threats (Jochim and others, pages 37-44). The list was prepared using “landslide” in its broadest sense, which included debris flow and rockfall areas. Hazard areas for which debris flows were the predominant hazard were listed separately in recognition of the fact that they nearly always occur in association with stream courses and their depositional fan areas. Both of these conventions are retained in the new Priority List herein.

The rationale for including this Priority List as an essential element of the Colorado Landslide Hazard Mitigation Plan was to provide an action list of manageable size which scarce staff and funding resources from a variety of sources would yield the greatest benefits. This concept has proven effective over the past fourteen years with significant progress in evaluation and/or mitigation being made in more than one-half of the areas. Funding and other substantial contributions have been provided by more than twenty state, federal, local, academic and private organizations.

The Year 2002 Review and Priority List was done as part of an update of the 1988 Colorado Landslide Mitigation Plan in cooperation with the Office of Emergency Management. Our charge is to review and revise, as needed, the action list. In this report, we will summarize new information or investigations, monitoring results and mitigation activity. We will also make an evaluation and recommendations on each case as deemed advisable.