Landslides in Colorado, USA: Impacts and Loss 

Estimation for the Year 2010

By Lynn M. Highland

Open-File Report 2012–1204

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director 

U.S. Geological Survey, Reston, Virginia: 2012

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Highland, L.M., 2012, Landslides in Colorado, USA—Impacts and loss estimation for 2010: U.S. 

Geological Survey Open-File Report 2012–1204, 49 p.

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endorsement by the U.S. Government.

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iii

Contents

Introduction.................................................................................................................................................... 1

Overview of Landslide-Loss Data Acquisition for the United States .............................................................. 1

A Note on Direct vs. Indirect Losses .......................................................................................................... 2

Study Area ................................................................................................................................................. 3

Overview of Landslides and Landslide Information for Colorado................................................................... 3

Significant Colorado Landslides in 2010—Impacts and Costs/Losses .......................................................... 4

1. Glenwood Canyon, Garfield County Rockfall/Slide, March 8, 2010—Losses and Cost Shifts............ 4

2. Amtrak train blocked by a rock slide in Gore Canyon, May 15, 2010 ................................................. 5

3. Big Thompson Canyon landslides, Larimer County, May 21, 2010 .................................................... 6

4. Debris flows in the Redstone, Carbondale, and Marble area of Colorado in July and August,........... 6

5 .Durango and Silverton Narrow Gauge Railroad debris flows, July 26, 2010 ...................................... 7

6. Clohsey Lake debris flows, San Isabel National Forest, Chaffee County, July 31, 2010.................... 7

7. Fourmile Canyon Fire, Boulder County debris-flow potential, September 6, 2010 ............................. 8

8. Amtrak Train blocked by rock slide in Gore Canyon, December 22, 2010 ......................................... 8

Other Landslide Events in 2010................................................................................................................. 9

The CDOT Rockfall Mitigation Program......................................................................................................... 9

Effects of 2010 Colorado Landslides on Roads and Highways.................................................................... 11

Effects of 2010 Colorado Landslides on Rail Transportation ....................................................................... 11

Effects of 2010 Colorado Landslides on Public Lands................................................................................. 11

Landslide-Related Disaster Declarations in Colorado for 2010.................................................................... 12

Conclusion................................................................................................................................................... 14

References Cited......................................................................................................................................... 14

Figures......................................................................................................................................................... 16

Appendix 1: Landslide Casualties in Colorado for the year 2010................................................................. 41

General Overview of Casualties Due to Landslides in Colorado.............................................................. 41

Appendix 2: List of All Sources of Information and Data not found in Reference Section............................ 43

Appendix 3: Notes on Landslide Loss Investigations and Lessons Learned ............................................... 46

Figures

1. Map of Colorado topography, showing major roads and cities.............................................................. 16

2. Map of alluvial fan and debris flow, potentially unstable soil, landslide inventory, and 

rockfall for Colorado.............................................................................................................................. 17

3. Interstate-70 in Glenwood Canyon, Colo. The March 8, 2010, rock slide closed the 

highway and damaged this elevated portion of Interstate-70 ................................................................ 18

4. Photo showing an overview of the 2010 Glenwood Canyon, Colo., rockfall showing 

damage to the road deck on the elevated portion of Interstate-70 ........................................................ 19

5. Rock-blasting by Colorado Department of Transportation (CDOT) after the March, 2010, Glenwood

Canyon rockfall, on Interstate-70 .......................................................................................................... 20

6. A photograph of the rock slide that blocked an Amtrak train on May 15, 2010...................................... 21

7. Photograph of the source area of the May 21, 2010, rockfall that impacted Highway 34 

near Estes Park, Colo ........................................................................................................................... 22
iv

 8. Colorado Department of Transportation (CDOT) crews breaking up rocks above the 

closed Highway 34 after the rockfall event of May 21, 2010, near Estes Park, Colo ........................... 23

 9. Redstone Campground inundated by mud, from the July 31, 2010 event........................................... 24

10. Deep mud from the debris-flow event of July 31, 2010, near a Redstone, Colo., 

campground. Photograph by Jeff Bier ................................................................................................. 25

11. The Redstone Campground debris flows, 10 months after the event .................................................. 26

12. August 19, 2010. Highway 133 was closed at Redstone, Colo., for several hours, 

but crews were able to reopen one lane.............................................................................................. 27

13. August 19, 2010. A photo of a debris flow on Katy Creek, on private property, 

near Redstone, Colo............................................................................................................................ 28

14. A Colorado Division of Transportation (CDOT) truck monitoring traffic and 

cleanup near Norwood ........................................................................................................................ 29

15. Aerial photograph of two debris flows that flowed over the Durango and Silverton 

Narrow Gauge Railroad—a scenic railroad company for tourists—that operates out 

of Durango, Colo ................................................................................................................................. 30

16. A close-up aerial view of the two debris flows that blocked the Durango Silverton 

Narrow Gauge Railroad track in July, 2010 ......................................................................................... 31

17. This debris flow occurred on July 31, 2010, in the San Isabel National Forest 

(near Leadville, Colo.) ......................................................................................................................... 32

18. The area of this photograph was located near Clohsey Lake campground in the 

San Isabel National Forest .................................................................................................................. 33

19. Photograph taken at the Clohsey Lake campground area, San Isabel National Forest 

on July 31, 2010 .................................................................................................................................. 34

20. One of two debris flows blocking Clohsey Lake Road in the San Isabel National Forest, 

near Leadville, Colo............................................................................................................................. 34

21. Photograph of a debris flow near Clohsey Lake in the San Isabel National Forest, near 

Leadville, Colo..................................................................................................................................... 35

22. Fourmile Fire burn area, northwest of Boulder, Colo........................................................................... 36

23. Slumping roadway above a retaining wall near Dillon Valley Reservoir.............................................. 37

24. Map of main highways and roads in Colorado .................................................................................... 38

25. Map of Colorado railroads................................................................................................................... 39

26. Map showing land ownership and management in the State of Colorado........................................... 40

Table

1. Total Loss/Cost Data for all landslides Investigated in Colorado for the Year 2010 .............................. 12
v 

Conversion Factors, Datum, Abbreviations, and Acronyms

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

meter (m) 3.281 foot (ft) 

kilometer (km) 0.6214 mile (mi)

kilometer (km) 0.5400 mile, nautical (nmi) 

meter (m) 1.094 yard (yd) 
Landslides in Colorado, USA—Impacts and Loss 

Estimation for the Year 2010

By Lynn Highland

Introduction

The focus of this study is to investigate landslides and consequent losses which affected 

Colorado in the year 2010. By obtaining landslide reports from a variety of sources, this report 

will demonstrate the feasibility of creating a profile of landslides and their effects on 

communities. A short overview of the current status of landslide-loss studies for the United 

States is introduced, followed by a compilation of landslide occurrence and associated losses and 

impacts which affected Colorado for the year 2010. Direct costs are summarized in descriptive 

and tabular form, and where possible, indirect costs are also noted or estimated. Total direct costs 

of landslides in Colorado for the year 2010 were approximately $9,149,335.00 (2010 U.S. 

dollars) and are summarized in table 1. (Since not all data for damages and costs were obtained, 

this figure realistically could be considerably higher.) Indirect costs were noted where available 

but are not totaled due to the fact that most indirect costs were not obtainable for various reasons 

outlined later in this report. Casualty data are considered as being within the scope of loss 

evaluation, and are reported in Appendix 1, but are not assigned dollar losses. More details on 

the source material for loss data not found in the reference section are reported in Appendix 2, 

and Appendix 3 summarizes notes on landslide-loss investigations in general and lessons learned 

during the process of loss-data collection.

Overview of Landslide-Loss Data Acquisition for the United States

Landslide-loss data for Colorado and other States exist in a wide variety of information 

sources, and the combined data can yield at least an approximation of total landslide losses, both 

direct and indirect. However, there is no current, ongoing compilation of comprehensive 

landslide-loss data for any of the 50 States, nor is there a targeted effort to acquire and maintain 

an accurate landslide inventory or a subset of loss data for the United States as a whole. The 

landslide-loss information that has been obtained appears in the following: There is little cost 

information for landslide losses for all of the United States, but what has been documented 

appears in the following: Schuster and Fleming, 1986; Schuster, 1996; National Research 

Council, 1999; Wang and others, 2002; Highland, 2003, 2006; and Crovelli and Coe, 2008. 

Much of the landslide documentation and inventory for landslides in Colorado can be found in 

Rogers (2003a, 2003b, and 2005). 

In this report, we attempt to quantify landslide losses in 2010, for the State of Colorado. 

Our goal is to demonstrate the feasibility of this quantification using a number of different data 

sources. One of the main impediments in acquiring accurate landslide-loss information is the 

lack of landslide inventory collection standards at a National level (although 10 states have 

landslide-inventory maps and other inventory information tailored to the particular needs of that 
2 

State). Some of the individual State Geological Surveys, including Colorado, have compiled 

landslide inventories for their respective States, although none use a common reporting or 

archiving method. Additionally, because landslide-inventory information usually does not 

extend beyond the borders of States that track it, the landslide-loss characteristics of regions 

across the United States are difficult to determine. As there is no national mandate or incentive to 

acquire or maintain a landslide inventory, associating historical landslide occurrences with losses 

is difficult. 

Until the 1990s when Global Positioning Systems (GPS) became widespread, landslide 

locations were described in terms of township/range locations, and (or) latitude/longitude taken 

from topographic or other types of maps. Some landslides were identified by street addresses,

highway mileposts, or distances from landmarks, making exact locations uncertain. Many 

compilations contain only partial data associated with larger significant events, leaving out small 

or less significant events. These compilations also contain gaps in time-frame and geographical 

location, and many reported landslide descriptions and locations are not field-checked for 

accuracy by State Geological Surveys, consultants or municipal planning and zoning 

departments. Generally, detailed information is available only when landslides are large and (or) 

have notable impacts on the built and natural environments. Cost data for landslide effects is 

sometimes even more difficult to acquire, due to privacy concerns that preclude the public 

release of cost data. Also, there are difficulties associated with extracting disparate information 

from data sources; that is, the landslide-loss data that a highway department keeps, for example, 

are in many instances combined with other types of tabulated costs. Data such as general debris 

clean-up costs, grading costs, and (or) road detour costs are not itemized sufficiently to separate 

the general losses from the individual landslide losses. 

Modern relational databases, Geographical Information Systems (GIS), GPS, Light 

Detection and Ranging (LiDAR), and other approaches/methodologies have vastly enhanced the 

siting, description, and mapping of landslides. These digital advances may contribute to the 

future cost-effectiveness of tracking landslides in a more systematic, homogenous manner. 

A Note on Direct vs. Indirect Losses

The losses from landslides described and tabulated in this report are organized into two 

categories: Direct and Indirect. Direct losses are the costs for repair, replacement, or maintenance 

resulting from damage to property or installations within the boundaries of the responsible 

landslides or from landslide-caused flooding (Schuster, 1996). All other losses from landslides 

are indirect. Some examples of indirect losses from landslides are:

1. Loss of industrial, agricultural, and forest productivity and tourist revenues as a result 

of damage to land or facilities or interruption of transportation systems;

2. Reduced real-estate values in areas threatened by landslides; 

3. Loss of tax revenues on properties devalued as the result of landslides; 

4. Measures that are required to be taken, to prevent or mitigate additional landslide 

damage;

5. Adverse effects on water quality in streams and irrigation facilities outside the 

landslide; 

6. Loss of human or animal productivity because of injury, death, or psychological 

trauma; and

7. Secondary physical effects, such as landslide-caused flooding, for which losses are 

both direct and indirect. 
3 

Study Area 

Figure 1 shows the State of Colorado along with the locations of Colorado’s largest cities 

and main highways. In order to get a broad understanding about landslide occurrence in 

Colorado, Figure 2 shows a general landslide, rockfall, alluvial fan and debris-flow map for 

Colorado released by the Colorado Department of Emergency Management, using data from the 

Colorado Geological Survey (Colorado Department of Emergency Management, 2011). 

Overview of Landslides and Landslide Information for Colorado

Landslides in Colorado are concentrated along the Front Range, central mountains, and 

western part of the State and are typically associated with areas of significant slope. Landslides 

are natural and ongoing events. Both human activity disrupting the land and periods of 

significant precipitation increase the likelihood of landslide occurrence. Many landslides have

not damaged structures, caused deaths or injuries, or impacted critical services or facilities. 

However, some landslides have resulted in deaths or significant damage to public infrastructure 

(Colorado Division of Emergency Management, 2011). The Colorado Geological Survey has 

been digitizing all mapped landslides that have been published in geologic and geologic hazard 

maps of Colorado and placing them in a GIS-based inventory map; however, the information for 

this current USGS Open-File Report loss study was obtained separately, as the Colorado 

inventory was released before the year 2010. The map generated by the Colorado Geological 

Survey is referenced here, for the reader’s information. The map is currently online at this link:

http://geosurvey.state.co.us/hazards/Landslides/Pages/CGSlandslide_inventory.aspx

(Jon White, Colorado Geological Survey (written commun., 2011).

Investigation of impacts and losses from Colorado landslides in 2010 was conducted 

mostly in the year 2011, with a follow-up in early 2012. Many types of sources were consulted 

and include: 

Newspaper and other media reports, including reports by government entities such as the 

Colorado Department of Transportation (CDOT); 

Costs incurred by municipal, county, and State governments for landslide hazardassociated expenditures; 

Electrical and power companies both private and public; 

Private consulting companies, for example, those involved in geotechnical engineering

and engineering geology; and 

Photographs of landslides were acquired where possible. 

It should be noted that some landslide events that occurred in 2010 may not have been 

documented and (or) studied by anyone, as they could have occurred in remote areas not 

inhabited or frequented by people. This is also the case for this report. Landslides that occur on 

private property are sometimes not reported or noted in any type of accessible information. 

Aerial photography can indicate past landslide activity in some areas, but does not provide a 

means of accurate dating without further analysis. Aerial photography was not checked for this 

report. Some landslides may have been noted but have not yet been mapped or cited in reports, 

as of this writing. 
4 

Significant Colorado Landslides in 2010—Impacts and Costs/Losses

1. Glenwood Canyon, Garfield County Rockfall/Slide, March 8, 2010—Losses and Cost Shifts

This rockfall occurred on March 8, 2010. It is estimated that at least 20 boulders fell onto 

Interstate-70, ranging in size from 1 to 3 meters (m) in diameter. The largest was estimated to 

have weighed about 66 tons. Figures 3 and 4 show damage caused by the rockfall. The rocks

made holes in the elevated sections of roadway, the largest being in the westbound lanes (closest 

to the hillside) and measuring 6.2 × 3.2 m. Another hole in the lower eastbound lanes measured 2 

× 2 m. There were several other holes and craters in the roadway, as well as areas where rocks 

were embedded. Most of the areas that needed repair appeared to be approximately 3.6 × 3.6 m.

Rocks were scattered over 100 m of roadway. Other rock-fall impacts included damage to three 

sections of steel guard rail and to sections of median barriers. This damage was similar to that 

from a 2004 rockfall. (Although the November 25, 2004, (Thanksgiving Day) rockfall was in the 

same general area, the rocks came from a different height on the slope.) 

The 2010 repair work took place between mile markers 124 and 125, just west of 

Hanging Lake Tunnel. The work involved bridge deck and bridge wall/rail repairs (including 50 

m, or 150 feet (ft), of new steel bridge rail); guardrail repairs (about 40 m or 120 ft) to the 

hillside concrete barrier; median concrete barrier repair (replacement of 133 m, (400 ft); removal 

and replacement of 690 square feet (ft2

) of concrete retaining walls; straightening of steel bridge 

girders; some lighting and electrical repairs; and repairs to the bike trail below. Finally, crews 

used approximately 500 tons of base course material on the roadway, as well as 400 tons of 

patching asphalt, to repair the driving surface.

 Flatiron Construction, with assistance from rockfall contractor Rock Solid Solutions, also 

installed 1,300 square meters (m2) (14,000 ft2) of wire mesh along a section of the canyon wall, 

near the bottom of the two chutes down which the rocks from the March 8 rockfall event

traveled. "The wire mesh is designed to keep smaller rocks (less than 1 m or 3 feet in diameter) 

that may release from the talus slope above from reaching the highway," CDOT Geologist Ty 

Ortiz said (oral commun., 2011). "The goal is to reduce the chances of these smaller 

rock incidents; the mesh is not intended to mitigate a large event like the one that occurred on 

March 8." (Tyler Ortiz, written commun., 2011). Figure 5 shows a photo of the rock-blasting by

CDOT on Interstate-70 subsequent to the rock slide, which was done in order to bring down any 

unstable rocks remaining in the area above the impacted road area. 

Total direct costs/losses from this rockfall event were: $2,180,000 

Then-Governor Bill Ritter declared a disaster emergency in 2010 to qualify for money 

from the Federal Highway Administration (FHWA) to help pay for repairs. The Colorado 

Department of Transportation expenses totaled $2.2 million, reimbursable by the FHWA. For 

comparison, the 2004 rock slide in the same area cost $700,000 to repair. 

CDOT is also requesting additional federal assistance to conduct a follow-up study on 

additional rockfall mitigation in the canyon. No information on costs for this mitigation work is 

currently available.

Indirect costs/losses: 

The rockfall that closed Interstate-70 through Glenwood Canyon forced truckers and 

other travelers onto a 200-mile (mi) detour that added hours to their trips and increased costs.

The closure cost trucking companies millions of dollars in fuel, work hours, and other costs. 

(Greg Fulton, president of the Colorado Motor Carriers Association, (written commun., 2011).

With Interstate-70 closed, Mr. Domenico of Domenico Trucking commented on conditions of 
5 

alternate routes: "They are good roads, but it is slow; we don't want to have an accident—it is 

narrow; and with the increased traffic, you need to keep your speed down. It is adding about six 

hours a run for our drivers.” When Interstate-70 is open, a typical trip from Denver to Glenwood 

Springs is about three hours, making a round trip six hours. With the interstate closed, it took 

drivers eight and a half to nine hours for one leg of the journey (Denver Post, 3/12/2011). 

According to Mr. Domenico, those increases in cost are passed on to consumers, who pay more 

for the products the trucks deliver to retailers. 

Cost shift associated with the Glenwood Canyon rockfall

The term “cost shift” is used here to indicate that losses to one entity resulting from a 

landslide may increase the income for other entities as a result of a given landslide; for example, 

an increase in business patronage and subsequent business income along a rerouted detour. The 

Union Pacific Railroad’s tracks through the closed Glenwood Canyon weren't affected by the 

2010 rockfall due to their location on the side of the Colorado River through Glenwood Canyon 

opposite the rockfall. The tracks carry freight trains and Amtrak's California Zephyr. The railway 

became a form of alternate transportation through the canyon during the rockfall road-closure.

Air travel using the many airports in the affected region also saw increased business. These 

airports included the Aspen Pitkin County Airport, Grand Junction Walker Field, Montrose 

County Airport, Yampa Valley Regional Airport, and Gunnison County Airport. (Report of 

Glenwood Springs Chamber of Commerce, March 11, 2010). Charter airline carriers reported 

brisk sales of $1,000 tickets for one-way rides between Eagle (east side of the rock slide) and 

Aspen (west side). Online bookings of short-notice flights from Denver to Grand Junction were 

priced as high as $850 round trip. Denver Air Connections, a charter company that flies four 

days a week between metro Denver (west side of rockfall) and Grand Junction (east side), 

reported an increase in business, at $300 round trip as its standard fare. Mountain Aviation in 

Denver began chartering seven-seat planes from Eagle to Aspen for $3,280 per plane each way. 

Various geotechnical engineering companies also benefited from increased income

associated with the 2010 rockfall. Costs incurred by CDOT, which is funded by the U.S. 

Department of Transportation, are ultimately costs to both State and Federal taxpayers. For 

purposes of this report, cost shifts were not analyzed in detail as there are incomplete loss data, 

and no guidance on the proper methods of performing a cost-shift analysis was found. 

2. Amtrak train blocked by a rock slide in Gore Canyon, May 15, 2010 

On Saturday, May 15, 2010, the westbound Amtrak California Zephyr encountered a 

rock slide in Gore Canyon between Plain and Crescent, about 30 mi west of Denver, Colorado 

(Colo.). The slide was near milepost 29.5 and Tunnel 17. Figure 6 shows a photo of the rock 

slide on the railroad track. Alerted by a monitoring device, the rail crew was warned of the rock 

slide and safely stopped the train short of the slide; however, the slide diverted the train to travel 

all the way back to Denver. Buses then moved passengers to their destinations (The Denver and 

Rio Grande Western Railroad news, May, 2010). Amtrak officials did not respond when queried 

about costs concerning this event. 

Total direct costs/losses: These loss figures were not obtained. Costs would be due to 

railroad track damage, fuel expended to return to Denver, employee time, and clean-up crew 

time.

Indirect costs: These consisted of lost time for Amtrak and for the passengers, but no 

specific data were obtained. 
6 

3. Big Thompson Canyon landslides, Larimer County, May 21, 2010

On May 21, 2010, at approximately 5:30 PM, about a dozen large rocks fell onto U.S. 

Highway 34 at milepost 75. A car traveling westbound on Highway 34 was struck by a large 

rock (photo), and the driver was uninjured (Trooper Cobler, Colorado State Patrol, written 

commun., May 21, 2010). This road connects the town of Estes Park with the town of Drake, 

Colo., through Big Thompson Canyon. See figures 7 and 8 for photos of the event. 

CDOT worked quickly to clear the road and repair damage, after closing the road on the 

evening of May 21. The State Patrol advised alternate routes through the canyon. CDOT crews 

began further mitigation activities by blasting and scaling loose rocks, bringing down about 500 

cubic yards of material. 

Total direct costs/losses: Big Thompson Canyon near Drake: $41,334.51, which includes 

the cost of a helicopter, a private consultant, and CDOT equipment and personnel (Tyler Ortiz, 

CDOT, written commun., April 29, 2011). Also included is the cost of damage to a 2006 

privately-owned car that had been hit by a rock (total cost of damages unknown). 

Indirect losses: These costs are principally the loss of business along Highway 34 during 

the detour. 

4. Debris flows in the Redstone, Carbondale, and Marble area of Colorado in July and August, 

Torrential rains which occurred on July 29, 2010, affected an area on the western slope of 

Colorado near the towns of Aspen, Carbondale, Marble, and Redstone. The storm triggered 

landslides that were reported by an Aspen Times newspaper as being too numerous to count. A 

number of effects were reported from this rainfall-induced landslide episode, including the 

following: a landslide near Carbondale closed westbound Highway 82, and multiple landslides 

occurred between Penny Hot Springs and Redstone, causing Highway 133 to be closed. The 

biggest debris flow hit Redstone Boulevard and the entrance to the Redstone Campground (figs. 

9 and 10). The debris flow was approximately 1.3 m (4 ft) deep and 100 m (300 ft) wide, and 

covered the north end of Redstone Boulevard and the entrance road to Redstone Campground; as 

a consequence, people in the 36 campground sites were trapped. Figure 11 shows the 

campground area 10 months after the event, where a person disappeared and has been missing 

since. Nine members of the Carbondale and Rural Fire Protection District rescued two people 

trapped in their car, which was caught in the debris flow. A major mudslide hit County Road 3 

just outside of the town of Marble, Colo. The mud was reported to have reached about 1.6 m (5 

ft) in height and was approximately 17 m (50+ ft) wide. The Crystal River, which flows through 

the valley, was turned from a clear, flowing mountain river into a “muddy muck.” (The Denver 

Post, 07/31/2010). Finally, a debris flow was also reported on Interstate-70, near Dotsero, and in 

Pitkin County, Snowmass Creek Road at mile marker 10, most likely due to the same storm 

system. There are more photos on the USGS Landslide Program website: 

http://landslides.usgs.gov/learning/photos/colorado__u.s._/redstone__carbondale__aspe

n_debris_flows__july__2010

The region was hit again on August 19, 2010, when heavy rain and hail produced three 

significant road closures at the north end of Redstone. Redstone Campground’s Osgood Loop, 

Dorais Way, and Highway 133 were all closed due to debris flows (fig.s 12 and 13). According 

to Mary Dorais, who owns property in the area, “When it started to hail you could hear and feel 

the earth shake and rumble. I never saw such a hard rain. Trees began to snap and boulders the 

size of small cars came down like they were floating on air. (Crystal Valley Echo, page 8).” In 

addition, state plows had to clear mud off Highway 145, near Norwood, Colo. (fig. 14). 
7 

In the Marble, Colorado area, on the upper Crystal River, Slate Creek became the path of 

a debris flow that covered and closed County Road 3 near the town of Marble, making the road 

impassable for many hours (The Crystal Valley Echo and Marble Times, September, 2010, vol. 

7, no. 9). CDOT provided cleanup, as did the Carbondale and Rural Fire Protection District, and 

Pitkin County personnel using a front-end loader. CDOT estimated that there was 6,000–6,500 

tons of debris to be removed (D’Wayne Gaymon, CDOT Region 3, written commun., May 12, 

2010). 

Total direct costs/losses: $34,000.00 

Indirect costs/losses: There were none estimated, although losses were probably incurred 

in the form of lost time and increased travel expenses driving on detour routes and lost revenue 

to businesses in the towns of Redstone and Marble. 

5 .Durango and Silverton Narrow Gauge Railroad debris flows, July 26, 2010 

On July 26, 2010, two debris flows on the Durango & Silverton Narrow Gauge Railroad 

(DSNGR) tracks prevented three trains and about 1,000 passengers from reaching Silverton. 

Geologist Jeff Coe, U.S. Geological Survey, visited this area after the occurrence and determined 

that despite the designation of “rock slide” given by some media, the event was actually two 

debris flows that flowed onto the track (oral commun., April 14, 2010). Heavy rains in the upper 

Animas Canyon led to the debris flows on Monday, July 26, closing the line to Silverton, and rail 

crews worked into the late evening clearing the slides and repairing the tracks so the line could 

reopen on Tuesday. The two debris flows ran across the railroad tracks and also into the Animas 

River (figs. 15 and 16). Some passengers were stranded on the train for 9 hours (hr) on Monday. 

A normal round-trip ride to Silverton involves seven hours on the train with two hours 

and 15 minutes in Silverton. One family paid $480 to ride the train initially, and said that

passengers were offered a 25-percent refund (Albuquerque Journal, July 29, 2010). More photos 

of this event can be viewed at this link, on the USGS Landslide Program website: 

https://landslides.cr.usgs.gov/learning/photos/admin/plogmanage.php?level=pictures&id=101

Total direct losses/costs obtained: Losses included lost revenue for the railroad in having 

to refund ticket prices and clear the tracks. No cost numbers were available.

6. Clohsey Lake debris flows, San Isabel National Forest, Chaffee County, July 31, 2010

On July 31, 2010, a 6-hr rainstorm was blamed for two debris flows in the backcountry 

between Buena Vista and Leadville, Colo. Roughly 40 people camping or hiking in the area were 

trapped above the debris flows, which blocked Clohsey Lake Road. Dozens of vehicles were also 

trapped. One debris flow was up to 7 ft deep and covered a four-wheel drive trail in the San 

Isabel National Forest in Chaffee County, according to a camper in the area. See figures 17–21 

for photos of the event. 

Total direct costs/losses obtained: Cost for equipment (excavator) was $3,500. This does 

not include salary (approximately 18 person-days total). (Jon Morrissey, U.S. Department of 

Agriculture [USDA], Forest Service, written commun., May 10, 2010). There were no data 

available on the cost of the rescue, although Chaffee County Search and Rescue was queried for 

information. 

Indirect costs/losses: These were the potential lost employment income for stranded 

people (ABC News online, 08/03/2011). 
8 

7. Fourmile Canyon Fire, Boulder County debris-flow potential, September 6, 2010

On September 6, 2010, a fire occurred in Fourmile Canyon, 5 mi northwest of Boulder, 

Colo. The fire burned 26 km2 (6,400 acres) and destroyed 169 homes (fig. 22). The wildfire 

stripped the area of vegetative ground cover and increased the potential for sudden and 

destructive flooding and debris flows. More than 60 percent of the burn area drains into Boulder 

Creek with another 18 percent draining into the Fourmile Canyon Creek. Studies by local, 

federal, and private-sector scientists suggested an increased risk of flooding along the Boulder 

and Fourmile Canyon creek floodplains for between 2 and 10 yr, with the increased risk 

measured at mild to severe (Boulder Daily Camera, 03/01/2011). 

Empirical models estimated that several of the burned drainage basins in Fourmile Creek 

and Gold Run had probabilities of debris-flow occurrence greater than 60 percent, and many 

more had probabilities greater than 45 percent; these probabilities are based on a 2-yr recurrence 

from a 1-hr-duration rainstorm (Ruddy and others, 2010). The moderately high probability of 

large-volume debris flows indicates a potential for substantial debris-flow impact to buildings, 

roads, bridges, culverts, and reservoirs located both within these drainages and immediately 

downstream from the burned area (Ruddy and others, 2010). 

In response to the post-fire debris-flow concern, Boulder Country established the 

Fourmile Emergency Stabilization Team (FEST) to study ways to mitigate the effects of the fire.

The FEST team was composed of county commissioners, plant ecologists, and representatives 

from the following organizations: Boulder County Open Space, Colorado Department of 

Transportation, the USDA Forest Service, the USDA National Resources Conservation Service 

(NRCS), and the USGS. The FEST assessment recommended distributing ground cover on the 

severely burned areas in order to promote revegetation and to minimize erosion and debris flow 

during spring and summer rains. 

Two episodes of post-fire debris flows were documented in the Fourmile Canyon burn 

area since the fire in 2010. On July 7, 2011, four reported debris flows occurred at mile marker 8 

and beyond, in Fourmile Canyon (http://www.youtube.com/watch?v=vaqneNMWOw). On July 

13, 2011, six roads (including Four Mile Road and Gold Run at Dixon) were closed due to debris 

flows; these are areas which were highlighted in the 2010 debris-flow potential report 

(http://denver.cbslocal.com/2011/07/13/debris-flows-closed-roads-fourmile-canyon/#T481frUnQ.email ). 

Direct Losses: There were no direct losses from post-fire debris flows in 2010. 

Indirect Costs/Losses: The 2010 total estimated costs for debris-flow mitigation in the 

Fourmile Canyon wildfire-burned area was $1,809,540 (Boulder County Fourmile Emergency 

Stabilization Team Report, 2011, p. 9). 

8. Amtrak Train blocked by rock slide in Gore Canyon, December 22, 2010

On December 22, 2010, rock slides triggered by heavy rain in Glenwood Canyon, 

Colorado, detoured train traffic between Granby and Glenwood Springs. The resultant delays 

caused Amtrak travel to be shut down for 2 days, between Salt Lake City, Utah, and Denver, 

Colo. Passengers were taken to their destination by buses. Amtrak did not respond to a request 

for cost/loss information (CBS Denver news online, 12/22/2010). 
9 

Other Landslide Events in 2010 

• February 15, 2010—About 7,000 tons of rock fell on U.S. Highway 50 about 2 mi west of 

Cotopaxi, Colo. Some of the boulders ranged in size from 5 to 20 tons. Costs involved 

cleanup by CDOT and a contractor of rock and small repairs to the highway. The highway 

was closed for a week. School was cancelled due to the rock blockage as students and staff 

would have had to take a 3-hr detour (KOAA Colorado Springs/Pueblo News, 02/20/2010). 

• March 2, 2010—A rock slide on Interstate-70 in De Beque Canyon, Colo. (east of Grand 

Junction at mile-marker 56), caused two traffic accidents (Channel 11 News website, 03/02/ 

2010). 

• August 5, 2010—Twelve cars were trapped by two debris flows between Leadville and 

Buena Vista, after a 6-hr rainstorm (Durango Herald August 5, 2010). 

• October 28, 2010—Road crews from CDOT spent a total of about $2,000,000 in 2010, fixing 

ongoing landslide-related damage on Interstate-70 between Eisenhower tunnel and 

Silverthorne, Colorado. The road had become uneven, and part of the road had begun to sink 

due to landsliding. Asphalt from the continual repaving of the bumps is now 1.6 m-(5 feet)-

deep in some areas. Crews from CDOT reinforced hill slopes with light-weight concrete 

columns installed under Interstate-70 to block and break up the sliding soil (Summit Daily 

News, 10/28/2010). 

• October 29, 2010—A rock slide occurred behind a Walgreens store in Dillon, Colo. A watermain break sent water down a 20-m (60-ft) retaining wall, causing it to fail. Two homes were 

evacuated and Little Beaver Trail was closed. Figure 23 shows a photo of road damage that 

occurred when the retaining wall failed. (Summit Daily News, 01/27/2010). 

• The May 14, 2008—East Fork San Juan River Landslide—this landslide resulted in 

monitoring and repairing of an Xcel Energy Company pipeline that runs through the 

landslide. The movement of the landslide cost $716,000 to fix (Chris Hartig, Xcel Energy, 

Denver, Colo., oral commun., 2011). Ongoing monitoring with extensometers and other 

devices produce real-time data on the status of the slide, and the slide is a continual cost to 

Xcel, with the amount of debris varying from year to year. 

• Ongoing Rockfall Mitigation throughout Colorado (includes 2010)—This section on rockfall

is included under “Notable Colorado Landslide Events of 2010,” because rockfall is a 

primary geologic hazard in Colorado and losses are incurred by the virtually continuous 

cleanup and mitigation measures associated with rockfall throughout Colorado. CDOT’s 

Rockfall Program receives about $4 million for rock-fall mitigation projects each year (Ortiz, 

2004), and this is the cost figure used for the year 2010. As this item is an important aspect of 

landslide costs, an explanation of the CDOT Rockfall Mitigation Program follows in the next 

section.

The CDOT Rockfall Mitigation Program 

The CDOT Rockfall Mitigation Program, which started in 1996, was created to track 

rockfall information, implement a rating system, and mitigate potential hazardous areas. When 

the program first began, CDOT received only $750,000 for mitigation statewide. Over the last 10 

years, funding for the Rockfall Program has quadrupled to $3 to $4 million a year to 

accommodate rising construction costs and to allow for additional rockfall mitigation across the 

state. To determine which sites are of high priority, several factors are analyzed including slope 

profile, geological characteristics, and traffic statistics. This information is then incorporated into 
10 

the Colorado Rockfall Hazard Rating System (CRHRS), and sites are then prioritized and 

selected based on their rating. The Colorado Rockfall Simulation Program (CRSP) is a useful 

computer software application for assessing and modeling rockfall hazard; the CRSP uses the 

simulation of rocks traveling down a slope to predict the speed, bounce heights, and runout 

distance of the rocks (Jones and others, 2000). This tool is updated from time to time and version 

4.0 is now available; version 5.0 is currently being tested. Since the rockfall-mitigation program 

began, about 60 sites have been mitigated. Rockfall specialists at CDOT also provide additional 

assistance at nearly 30–40 locations statewide each year in response to rockfalls and other 

activity (Mears, 2009). The town of Telluride, Colo., has investigated its rockfall hazard using 

the CRSP software as one of its tools. 

Through its regular funding, CDOT received $4.3 million for rockfall-mitigation projects

for 2010 (Colorado Department of Transportation, 2011b, p. 42). Due to the addition of Funding 

Advancements for Surface Transportation and Economic Recovery (FASTER) money, CDOT 

was able to accelerate a few of the projects. An additional $700,000.00 was allocated by the 

State Transportation Commission for repairs to rockfall devices and to repair and update fences 

in Glenwood Canyon. According to CDOT, there are 756 locations statewide having chronic 

rockfall issues. Just about every canyon in the mountains has some type of rockfall concern

(Ortiz, 2004). 

• Interstate-70 in Glenwood Canyon: Crews will continue to repair and improve existing 

rockfall fences in Glenwood Canyon. This $600,000 project was scheduled to begin in the 

summer of 2010. 

• Interstate-70 at Georgetown Hill: The $1.4 million project will continue rockfall

mitigation at one of the state’s most active sites by installing rockfall fencing and draped rockfall

netting. Construction was started in late fall 2010 and continued through calendar year 2011. 

• U.S. 285 in Turkey Creek Canyon: The project consists of rock scaling, blasting, and 

installation of rockfall netting. The rockfall-mitigation work will be combined with a safety 

improvement project on US 285 between Bailey and Richmond. The rockfall mitigation work is 

expected to cost between $150,000 and $300,000. 

• State Highway 82 at Shale Bluffs: This project involves the installation of draped 

rockfall netting along SH 82 between mileposts 35 and 37. The site is being funded with 

$350,000 from the rockfall program and the rest, $1.2 million from FASTER safety funds. This 

project was originally scheduled to take place in fiscal year 2013, but was accelerated two years 

due to the availability of FASTER funds. Construction began in late summer to early fall 2010 

(Tyler Ortiz, CDOT, written commun., 2012). 

• State Highway 145 at Norwood Hill: This $1.7 million project consists of rock scaling 

and installation of draped rockfall netting (of the total, $200,000 was National Highway System 

funding). The project began in July 2010 (Tyler Ortiz, CDOT, written commun., 2012. 

• State Highway 133 at McClure Pass: CDOT has evaluated this site to determine 

mitigation activities, which could include rock scaling, blasting, and installation of rockfall

netting. Construction was set to begin in the spring of 2011 and is expected to cost 

approximately $1.2 million. 

• Interstate-70 rockfall mitigation project on Interstate-70 in De Beque Canyon: 

Completion of the work was accomplished in May, 2010. CDOT contracted out a total of 

$380,000 for this maintenance project. 

• State Highway 145 from mileposts 96 to 98 in San Miguel County: This project consists 

of rockfall mitigation at three separate sites including cable netting and wire mesh, mesh 
11 

anchors, rock anchors, and polyurethane resin on added upon completion. The total cost is

$1.78 million. 

Note: These costs most likely exceed the $4,000,000 cost figure used in this report for 

2010 rockfall mitigation costs. However, the projects may extend through years beyond 2010. 

Effects of 2010 Colorado Landslides on Roads and Highways 

Figure 24 shows a map of major Colorado roadways. Many of Colorado’s landslides 

occur along transportation networks due to the fact that the soil and rock has been disturbed in 

some manner, and construction occurred with or without proper landslide hazard mitigation 

procedures. The cost to maintain, cleanup, monitor, and repair roads and highways from 

landslide activity is difficult to assess, but the best records come from CDOT, which is 

responsible for maintaining Colorado roads and highways. Other roads in Colorado are either 

managed by cities and counties, the Federal or State government, or are privately owned.

Landslide costs and losses are often combined with general maintenance costs for a city or 

county, and the specific landslide-related costs are not itemized, making them more difficult to 

discern.

Effects of 2010 Colorado Landslides on Rail Transportation

Landslide events occurring on, or near, Colorado railways always have the potential to 

significantly impact rail transportation in Colorado, as there is no cost-effective way of routing 

railroads around landslides especially rockfall. Some tunnels exist through hazardous areas, but 

they are extremely expensive to build. Railroads are routinely subject to rockfall, and (or) rock

slides, and the railroads have therefore devised various ways of dealing with this hazard. 

Approaches include the use of small scout vehicles that sweep the tracks for rocks ahead of a 

moving train, and trip-wires that indicate a rockfall or rock slide in particularly susceptible areas 

known to cause ongoing problems. Figure 25 shows a map of railroad lines in Colorado. 

Railways are very vulnerable to landslides. There were two notable rock slide events and one 

debris flow event that impacted railroad travel in 2010. Although the effects can be documented, 

it is difficult to acquire costs from landslide damage to railways, as costs are not normally 

provided to the public. 

Effects of 2010 Colorado Landslides on Public Lands

Figure 26 shows a map of public lands in Colorado. Currently, 46 percent of Colorado is 

public lands. Large tracts of land in Colorado are managed by the Forest Service, Bureau of Land 

Management, National Park Service, Indian tribal lands, and other Federal agencies, in addition 

to Colorado state, county, and city governments. Tracking landslides on public lands is not done 

on a systematic basis; in fact, the only time landslides are usually noted is when they interfere 

with public access (roads, highways), or with campers, sportsmen, mountain climbers, hikers, 

campground operation and maintenance, logging roads, or riverine blockage. In 2010, there were 

several instances of campers being trapped and roads being blocked by debris flows/mudslides. 

Total costs of these events are not generally tracked. These costs would include man-hours for 

federal or state workers such as search and rescue personnel, road crews, and equipment for 

cleanup; and maintenance, fuel, and (or) costs associated with managing detours. All of the 

deaths from landslide-related hazards that were found to be documented for 2010 were on public 

lands or highways. 
12 

Three documented significant landslide events occurred on public lands in 2010. These 

landslides include debris flows that occurred July 31 in the Clohsey Lake campground area of 

San Isabel National Forest, near Leadville, Colo.; the Durango Silverton Narrow Gauge railroad 

debris flows that occurred in the San Juan National Forest (the debris flows flowed onto private 

railroad property); and the Redstone Campground debris flows of July 30, in the White River 

National Forest and along Highway 133 through this National Forest. There are, no doubt, many 

more landslides that have occurred and will continue to occur on Colorado’s public lands. It is a 

challenge to document and inventory these landslides because of the vast areas involved and the 

scarcity of funds and personnel to map, observe, and report every landslide. Loss data are

sporadic and difficult to document, and data most likely exist in a wide variety of sources.

Landslide-Related Disaster Declarations in Colorado for 2010

1. A disaster declaration was made by then-Fovernor of Colorado, Bill Ritter, regarding 

the March 8, 2010, rockfall/rock slide incident on Interstate-70, Colorado: 

http://www.colorado.gov/cs/Satellite%3Fc%3DPage&childpagename%3DGovRitter%25

2FGOVRLayout&cid%3D1251572415216&pagename%3DGOVRWrapper

2. On April 4, 2010, Colorado Governor John Hickenlooper issued an emergency 

disaster declaration due to the imminent threat posed by flooding as a result of the wildfire last 

fall in Fourmile Canyon. “The wildfire stripped the burn area of vegetative groundcover and, as a 

result, according to the U.S. Geological Survey, the potential for sudden and destructive flooding 

and debris flow is dramatically increased,” according to the declaration. 

The declaration also stated the Fourmile Emergency Stabilization Team recommends 

distributing groundcover on the severely burned areas to promote revegetation and to minimize 

erosion and debris flow during spring and summer rains. “Due to steep terrain in the burn area, 

aerial distribution of mulch is necessary.” The aerial mulching effort will use no State funds and 

will be conducted using Federal funding from the U.S. Department of Agriculture. Specifically, 

the funds will be used by Boulder County to contract for aerial mulching in the Fourmile Fire 

burn area. These declarations are cited on State and Federal websites. For this report, the full text 

of the Declaration is linked here:

http://www.colorado.gov/cs/Satellite?c=Page&childpagename=GovHickenlooper%2FC

BONLayout&cid=1251590836028&pagename=CBONWrapper

FEMA (Federal Emergency Management Agency) issued a Fire Management Assistance 

Declarations for this incident but did not fund mulching or any other debris-flow potential 

mitigation. 

Table 1. Total Loss/Cost Data for all landslides Investigated in Colorado for the Year 2010.

Landslide Date 

(2010)

Direct 

losses/costs ($) Description of indirect losses/costs

Glenwood Canyon 

Rock slide, Garfield 

County

March 8 $2,180,000 (CDOT, 

including private 

Geotechnical 

consultants)

Trucking industry re-routing of 200 miles around 

the slide. Lost time on delivery schedules, loss of 

tourism dollars (skiing, hot springs, businesses on 

both sides of the road) closure for several weeks, 

cost of taking alternate forms of transportation 

through the canyon such as air and rail.
13 

Table 1. Total Loss/Cost Data for all landslides Investigated in Colorado for the Year 2010.—Continued

Landslide Date

(2010)

Direct

losses/costs ($) Description of indirect losses/costs 

Rockfall at Big 

Thompson Canyon 

near Drake, Larimer 

County, at milepost 75 

on U.S. Highway 34

May 21 $41,335 (CDOT, including 

private Geotechnical 

consultant contractors). 

Rockfall damage to 

privately owned vehicle 

(unknown). 

Closure of road by CDOT to do further blasting 

and rock scaling of rock slide area—detour 

through Lyons, Colo. Loss of business income 

along detoured route.

Clohsey Lake debris 

flows, San Isabel 

National Forest, 

Chaffee County

July 31 $3,500 for excavator Salaries for extra work in clearing roads and 

campgrounds (18 person days), fuel, cost of 

rescuing stranded hikers

Redstone & 

Carbondale area, 

Pitkin & Garfield 

Counties

August 19 $34,000 (CDOT, including 

private Geotechnical 

consultant contractors) 

Traffic delays due to temporary closures, loss 

of tourist and roadside business income

Jackson Mountain, 

U.S. Highway 160. 

Archuleta County 

Work began in fall, 

2010 to stabilize the 

landslide with 

engineered solution 

September, 

2010 to April 

2012

(CDOT) including private 

Geotechnical consultant 

contractors: For 2010: 

$175,000

(Note: $5,200,000 was 

allocated over a period of 

years) 

Same

East Fork of the San 

Juan River

May 14, 

2008–2010 

and ongoing

$716,000 Xcel Energy 

pipeline relocation, and 

maintenance for year 2008; 

costs are ongoing for 

pipeline adjustment and 

monitoring equipment 

placed on landslide, and 

private consultants (no 

figures available)

No real indirect costs, as the pipeline did not 

have to be shut down, which would have meant 

a cutoff of gas service to homes and businesses.

Landslide mitigation 

on Interstate-70 

between the 

Eisenhower Tunnel 

and Silverthorne, Colo. 

October, 

2010, 

reported by 

CDOT

$2,000,000 Unknown

CDOT Rockfall

Mitigation program

Year 2010 $4,000,000 (CDOT, 

including private 

Geotechnical consultants)

Cost of detours to traffic, while blasting and 

clearing roads; commercial trucking delay time, 

extra fuel costs for idling traffic (delays of up 

to 1⁄2 hour for all traffic, sometimes both ways)

Total Estimated Direct 

Costs/Losses

(2010 U.S. Dollars)

Year 2010 $9,149,335 Not totaled due to the difficulty of obtaining 

indirect costs—total indirect costs are probably 

considerable.
14 

Conclusion

This summary of losses is extremely conservative. The actual landslide-related loss totals 

are likely much greater than has been documented in this report. Some loss totals may be 

available in the future, but unless a targeted, collective approach to tracking landslide losses is 

undertaken, these loss numbers for the year 2010 will only give a partial picture of what 

landslide-related hazards actually cost in Colorado. It is not possible to accurately estimate or 

project a total loss number, except for the category of casualties. Landslide-related casualty 

reports for Colorado indicate nine people were killed and three were injured in 2010. For more 

detailed information on Colorado losses for the year 2010 and landslide loss assessments in 

general, please see the report appendices.

References Cited

Colorado Department of Transportation, 2011b, Annual Report—Fiscal Year 2009–2010: 

Denver, Colo., Colorado Department of Transportation, 26 p., accessed on August 08, 2012, at, 

http://www.coloradodot.info/library/AnnualReports. 

Colorado Division of Emergency Management, 2011, State of Colorado Natural Hazards 

Mitigation Plan, 2011: Denver, Colo., Colorado Division of Emergency Management, 

accessed on August 08, 2012, at, http://www.colorado.gov/cs/Satellite/DOLAMain/CBON/1251595686517

Colorado Fourmile Emergency Stabilization Team, 2011, Fourmile Canyon fire emergency 

stabilization plan: Boulder, Colo., Colorado Fourmile Emergency Stabilization Team Report, 

accessed August 08, 2012, at, 

http://www.bouldercounty.org/find/library/environment/fest4mileburnedareareport.pdf

Crovelli, R.A., and Coe, J.A., 2008, Probabilistic methodology for estimation of number and 

economic loss (cost) of future landslides in the San Francisco Bay Region, California: U.S. 

Geological Survey Open-File Report 2008–1116, 27 p. (Also available at 

http://pubs.usgs.gov/of/2008/1116/.) 

Fleming, R.W., and Taylor, F.A., 1980, Estimating the costs of landslide damage in the United 

States: U.S. Geological Survey Circular 832, 21 p. 

Highland, L.M., 2006, Estimating landslide losses—Preliminary results of a seven-state pilot

project: U.S. Geological Survey Open-File Report 2006–1032, 11 p. (Also available at 

http://pubs.usgs.gov/of/2006/1032/.) 

Highland, L.M., 2003, An account of preliminary landslide damage and losses resulting from the 

February 28, 2001, Nisqually, Washington, Earthquake: USGS Open-File Report 03–211, 48 

p. (Also available at http://pubs.usgs.gov/of/2003/ofr-03-211/) 

Jones, C.L., Higgins, J.D., and Andrew, R.D., 2000, Colorado rockfall simulation program, 

Version 4.0: Colorado Geological Survey, Colorado Department of Transportation, and 

Colorado School of Mines, accessed August 08, 2012, at, http://geosurveystore.state.co.us/p676-colorado-rockfall-simulation-program-version-40.aspx 

Mears, A.I., 2009, Rockfall hazard and risk study, Telluride and Highway 145 Spurs: Gunnison, 

Colo., Arthur I. Mears, P.E., Inc., Report prepared for the Town of Telluride, Colo., 25 p., 

accessed August 08, 2012, at http://www.tellurideco.gov/Modules/ShowDocument.aspx?documentid=709. 

National Research Council, 1999, The impacts of national Disasters—A framework for loss 

estimation: Washington, D.C., National Academy Press, 128 p. 
15 

Ortiz, Tyler, 2004, Rockfall Mitigation Project Plan, FY 2005 through FY 2010: Denver, Colo., 

Colorado Department of Transportation, accessed August 08, 2012, at, 

http://www.coloradodot.info/search_cache?UE=http%3A//www.coloradodot.info/business/des

ignsupport/policy-memos/archived-policy-memos/RMPP%2525202005-2010%252520-

Revised%2525202-6-

04.pdf/view&SearchableText=rockfall%20mitigation%202010&CID=OG7rcbjJx-oJ

Rogers, W.P., 2005, Critical landslides of Colorado: Colorado Geological Survey Open-File 

Report 03–16. [CD-ROM] 

Rogers, W.P., 2003a, Critical landslides of Colorado—A year 2002 review and priority list: 

Colorado Geological Survey Open-File Report 02–16, 1 map. 

Rogers, W.P., 2003b, Map of critical landslides of Colorado, in Boyer, D.D., Santi, P.M., and 

Rogers, W.P., eds., Engineering geology in Colorado—Contributions, trends, and case

histories: Association of Engineering and Environmental Geologists, Special Publication 15, 

Colorado Geological Survey Special Publication 55. [CD-ROM] 

Ruddy, B.C., Stevens, M.R., Verdin, K.L., and Elliott, J.G., 2010, Probability and volume of 

potential post wildfire debris flows in the 2010 Fourmile burn area, Boulder County, Colorado: 

U.S. Geological Survey Open-File Report 2010–1244, 5 p. (Also available at 

http://pubs.usgs.gov/of/2010/1244/.) 

Schuster, R.L. 1996, Socioeconomic significance of landslides, in Turner, Keith, and Schuster, 

R.L., eds., Landslides—Investigation and mitigation: Washington, D.C., National Research 

Council, National Academy Press, Transportation Research Board Special Report 247, p. 3–

35. 

Schuster, R.L., and Fleming, R.W., 1986, Economic losses and fatalities due to landslides:

Bulletin of the Association of Engineering Geologists, v. 23, no. 1, p. 11–28. 

U.S. Census Bureau, 2010 American Community Survey, 

http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=ACS_10_1Y

R_B01003&prodType=table

U.S. Census Bureau, 1966, 1960 Census of Population, supplementary reports, Washington, 

D.C., p. 2. 

Wang, Y., Summers, R.D., and Hofmeister, R.J., 2002, Landslide loss estimation pilot project in 

Oregon: Oregon Department of Geology and Mineral Industries, Open-File Report O-02-05, 

45 p., accessed August 08, 2012, at http://www.oregongeology.com/sub/Landslide/O0205.pdf
16 

Figures

Figure 1. Map of Colorado topography, showing major roads and cities. Elevation is lowest in light-greencolored area and highest in brown- and gray-colored areas. Map is modified from a map found in the 

Colorado Division of Emergency Management report (2011).
17 

Figure 2. Map of alluvial fan and debris flow, potentially unstable soil, landslide inventory, and rockfall for 

Colorado. This map is modified from a map created by the Colorado Department of Emergency 

Management, using data from the Colorado Geological Survey (Colorado Division of Emergency 

Management, 2011). 
18 

Figure 3. Interstate-70 in Glenwood Canyon, Colo. The March 8, 2010, rock slide closed the highway and 

damaged this elevated portion of Interstate-70. Photograph by Colorado Department of Transportation. 
19 

Figure 4. Photo showing an overview of the 2010 Glenwood Canyon, Colo., rockfall showing damage to 

the road deck on the elevated portion of Interstate-70. Photograph by Colorado Department of 

Transportation. 
20 

Figure 5. Rock-blasting by Colorado Department of Transportation (CDOT) after the March, 2010, 

Glenwood Canyon rockfall, on Interstate-70. These rocks were removed because they were 

precariously poised above the rockfall area, could endanger workers repairing the highway, and could 

possibly be a threat to the highway in the near future. Photograph by CDOT.
21 

Figure 6. A photograph of the rock slide that blocked an Amtrak train on May 15, 2010. The train had to 

return to Denver, a distance of about 48 kilometers (30 miles). (Photo by “Rovertrain” on 

http://www.Trainorders.com) 
22 

Figure 7. Photograph of the source area of the May 21, 2010, rockfall that impacted Highway 34 near 

Estes Park, Colo. Inset shows a road-level photograph of the area on the highway where rocks fell.

Photograph and graphics courtesy of Tyler Ortiz, Colorado Department of Transportation. 
23 

Figure 8. Colorado Department of Transportation (CDOT) crews breaking up rocks above the closed 

Highway 34 after the rockfall event of May 21, 2010, near Estes Park, Colo. The rock was brought 

down and hauled away to mitigate the rockfall hazard. Photograph courtesy of Tyler Ortiz, CDOT.
24 

Figure 9. Redstone Campground inundated by mud, from the July 31, 2010 event. (Photo by Jeff Bier.)
25 

Figure 10. Deep mud from the debris-flow event of July 31, 2010, near a Redstone, Colo., campground.

Photograph by Jeff Bier. 
26 

Figure 11. The Redstone Campground debris flows, 10 months after the event. There was one person 

missing and presumed dead, as a result of the debris flow in July, 2010. Photograph by Lynn Highland, 

USGS, taken on May 19, 2011.
27 

Figure 12. August 19, 2010. Highway 133 was closed at Redstone, Colo., for several hours, but crews 

were able to reopen one lane. There were six drainages where mud crossed Highway 133, taking out 

100 feet (33.3 meters) of guardrail. The Crystal River (which flows parallel to Highway 133) is shown in 

the foreground. Photograph by Sue McEvoy. 
28 

Figure 13. August 19, 2010. A photo of a debris flow on Katy Creek, on private property, near Redstone, 

Colo. Photograph is courtesy of Mary Dorais, property owner.
29 

Figure 14. A Colorado Division of Transportation (CDOT) truck monitoring traffic and cleanup near 

Norwood. Photograph by CDOT, August 20, 2010.
30 

Figure 15. Aerial photograph of two debris flows that flowed over the Durango and Silverton Narrow Gauge 

Railroad—a scenic railroad company for tourists—that operates out of Durango, Colo. The photo was

taken by a zipline participant as he was passing over the area. Photograph courtesy of Tall Timber 

Resort/Soaring Tree Top Adventures.
31 

Figure 16. A close-up aerial view of the two debris flows that blocked the Durango Silverton Narrow Gauge 

Railroad track in July, 2010. Cleanup was performed by railroad crews. Photograph courtesy of Tall 

Timber Resort/Soaring Tree Top Adventures.
32 

Figure 17. This debris flow occurred on July 31, 2010, in the San Isabel National Forest (near Leadville, 

Colo.). The area experienced 6 hours of heavy rain, which was thought to have triggered two large 

debris flows in the area. Photograph by Mary Widner.
33 

Figure 18. The area of this photograph was located near Clohsey Lake campground in the San Isabel 

National Forest. The photo was taken on July 31, 2010. Forty campers were trapped for a number of 

hours and 15 eventually had to be rescued by Chaffee County Search and Rescue.
34 

Figure 19. Photograph taken at the Clohsey Lake campground area, San Isabel National Forest on July 

31, 2010. This man, who is 5’ 10” tall, is indicating the height that one of the two large debris flows 

reached as it moved through the area (red arrow). Photograph by Mary Widner.

Figure 20. One of two debris flows blocking Clohsey Lake Road in the San Isabel National Forest, near 

Leadville, Colo. Forty campers were initially trapped and 15 had to be rescued. Photograph by Tim 

Ransom.
35 

Figure 21. Photograph of a debris flow near Clohsey Lake in the San Isabel National Forest, near 

Leadville, Colo. Photograph courtesy of Jon Morrissey, US Department of Agriculture National Forest 

Service. 
36 

Figure 22. Fourmile Fire burn area, northwest of Boulder, Colo. Photograph by John G. Elliott, US

Geological Survey, September 23, 2010. 
37 

Figure 23. Slumping roadway above a retaining wall near Dillon Valley Reservoir. Officials are trying to 

determine what caused the retaining wall to fail after a water main broke nearby. Photograph by Lake 

Dillon Fire-Rescue. 
38 

Figure 24. Map of main highways and roads in Colorado. This map is modified from a map created by the

Colorado Department of Emergency Management, using data from the Colorado Division of 

Transportation (Colorado Division of Emergency Management, 2011) 
39 

Figure 25. Map of Colorado railroads. This map was modified from a map created by the Colorado 

Department of Emergency Management, using data from the Colorado Department of Transportation

(Colorado Department of Emergency Management, 2011). 
40 

Figure 26. Map showing land ownership and management in the State of Colorado. The map is modified 

from a map created by Colorado Department of Emergency Management with data from the U.S. 

Census Bureau and COMap, a project at Colorado State University. Forty-six percent of Colorado is 

public lands (Colorado Department of Emergency Management, 2011).
41 

Appendix 1: Landslide Casualties in Colorado for the year 2010

General Overview of Casualties Due to Landslides in Colorado

The State of Colorado Hazard Mitigation Report (Colorado Department of Emergency 

Management, 2011), and the Hazards & Vulnerability Research Institute (2010), has documented 

5 deaths and 10 injuries due to landslides in Colorado dating from the year 1960 to the year 

2008. For the year 2010, nine deaths and four injuries caused by various types of landslides 

were documented. For this report, dollar-loss data have not been documented or assigned to 

casualties. These deaths and injuries are described in the next section of this Appendix. As 

mentioned previously, Colorado’s population has steadily increased since 1960, and it is 

probable that more people are vulnerable, due to increased population exposure to landslide 

hazard. Colorado’s population is now over 5 million (U.S. Census Bureau, 2010) as compared 

to a population of 1.75 million in 1960 (U.S. Census, 1966). Tourists and outdoor enthusiasts 

have also risen in number; this most likely increases the number of people with exposure to 

landslide hazards (vulnerability). 

In addition, the population of Colorado has increased at a rate of 30 percent between the

years 1990 and 2000 and about 10 percent in the years from 2000–2008 (U.S. Census Bureau, 

2010). Although there is no present documentation of a commensurate increase in the rate of 

landside-related casualties with increased population, there may be a relationship that would 

show a higher rate of casualties from landslides. 

 A USGS report (Fleming and Taylor, 1980) estimated a landslide-related death rate for 

the United States at between 25 and 50 people per year, not including injuries from landsliderelated events. This estimate has not been updated, as there is no single entity that is charged 

with keeping an official count of landslide-related deaths and injuries. Information on casualties 

is gleaned from scientific reports, newspaper reports, blogs, and personal communications, as is 

the case for assessing 2010 casualty numbers for Colorado. 

Also, some economists include the “value of human life” as a means of characterizing 

loss, but there are many definitions of this value, and this paper does not include a dollar 

evaluation for the loss of human life. 

• March 10, 2010. A woman was killed in March by a falling rock that hit her car on a stretch 

of Highway 40, east of Hayden, Colorado (Steamboat Today, March 10, 2010). 

http://www.steamboattoday.com/news/2010/mar/10/woman-killed-when-boulder-hits-carnear-mount-harr/

• July 26, 2010. After leaving El Diente's summit, (a mountain in Dolores County), a group of 

five climbers worked their way along the ridge towards Mount Wilson. They reached a notch 

on the ridge and were climbing up a steep gully to the next ridge point when a climber above 

dislodged some loose rock, which cascaded down, hitting three of the climbers below. The 

one victim who died was wearing a helmet; however, the rockfall hit him in the head and 

torso, knocking him unconscious and eventually killing him. It is not known if the victim’s 

group caused the rockfall or if another group ahead of them accidently dislodged the rocks 
42 

and triggered the rock fall. http://100summits.com/articles/colorado-mountaineeringdeaths/2010.html#intro

• July 30, 2010. Redstone area debris flows: A man is missing and presumed dead as his car 

was found very near the Redstone Campground area, and he was last reported to be hiking in 

the area of the debris flows (oral commun., Carrie Click, The Crystal Valley Echo and 

Marble Times, May, 2011.) 

• July 27, 2010. A couple was washed to their deaths during a very violent storm on Crestone 

Needle, a mountain in Custer County in southern Colorado. They were ascending a nearvertical cliff when they were hit by a torrential downpour of rain. They fell about 152 m (500 

ft) and then were carried about 100 m (300 ft) farther by a debris flow that buried their 

bodies. "It was very violent. It looks like a huge amount of water came down that washed 

them off the mountain. The mudslide buried them.” (Custer County Coroner Art Nordyke). 

http://www.thedenverchannel.com/news/24473412/detail.html

• August 14, 2010. While traversing what is known as one of Colorado's "Four Great 

Traverses" between North Maroon Peak and Maroon Peak (mountain near Aspen, Colo.), a 

rock was dislodged from above, which struck the victim, knocking him 200 m (600 ft) down 

the Bell Cord Couloir. The victim was wearing a climbing helmet at the time of the incident. 

It was believed that a member of the victim’s climbing party knocked the rock loose that 

knocked him down. The Maroon Bells area, where the victim died, is home some of the most 

treacherous, loose rock of any mountains in Colorado. 

• http://100summits.com/articles/colorado-mountaineering-deaths/2010.html#intro

• September 26, 2010. A climber was crushed by a rockfall on El Diente Peak in nearly the 

same location as the death described on July 26, 2012, and exactly two months later. The 

victim’s dog, Oof, was rescued by a Search and Rescue operation the following day. 

http://100summits.com/articles/colorado-mountaineering-deaths/2010.html#intro

• October 26, 2010. A woman was killed after a rock hit her car on a stretch of Highway 40 

east of Hayden, Colo. Another woman was injured as a rock hit her car windshield the 

previous Sunday, October 24, 2010. This incident occurred very near where a previous car 

was hit by a falling rock in March (see the first death described). CDOT speculated that it 

could be a result of the freeze-thaw cycle, and wild mountain goats had been spotted on the 

slopes in the area; they could have dislodged the rock while traversing the slope (Steamboat 

Today, October 26, 2010). 

• http://www.steamboattoday.com/news/2010/oct/26/rock-through-womans-windshieldreported-us-highway/

• June 17, 2010. A boy dislodged a rock on a hiking trail, and it hit a 17-year old girl who was 

killed when the rock struck her head. The incident occurred near Estes Park, Colo. The 

incident was ruled an accident, even though the rock was apparently dislodged purposely, 

although not intended to hit the victim. 

• http://www.mlive.com/news/grand-rapids/index.ssf/2011/01/charges_dismissed_in_rockkick.html
43 

• September 29, 2010. A rock-slide injury occurred where three cars collided with rocks that

fell on east-bound Interstate-70 near Palisade. It was unclear whether the cars hit the rocks, 

or vice versa. Three people were injured and taken to the hospital in Grand Junction (ABC 

News report, 10/29/2010). 

Appendix 2: List of All Sources of Information and Data not found in 

Reference Section

Note: Some of the internet URL addresses listed in this appendix may change over time 

and the information then becomes part of a separate archive, or can only be found by means of 

an internet search engine. 

March 8, 2010 Rockfall, Glenwood Canyon, Colorado 

Newspaper reports:

Interstate-70 Reopened Through Glenwood Canyon (The Denver Post, March 12, 2010), 

http://www.denverpost.com/ci_14660036

Interstate-70 rock-slide closure costs truckers valuable time and money (The Denver 

Post, March 12, 2010) 

http://www.denverpost.com/recommended/ci_14644221 

(Greg Fulton, president of the Colorado Motor Carriers Association, oral commun., 

2011). 

He estimated the closure cost trucking companies millions of dollars in fuel, work hours, 

and other costs. 

Press release issued March 8, 2010: Interstate-70 rockfall Disaster Declaration, thenGovernor of Colorado, Bill Ritter (Colorado Government web portal, Disaster Declaration for 

March 8, 2010): 

http://www.colorado.gov/cs/Satellite?c=Page&childpagename=GovRitter%2FGOVRLay

out&cid=1251572415216&pagename=GOVRWrapper

2010 Annual Report, Colorado Department of Transportation (CDOT) News and 

website:

http://www.coloradodot.info/library/AnnualReports/AnnualReport_2010_downloadable.

pdf/view

Rock slide in De Beque Canyon, Colorado, March 2, 2010 

Rock slide and Accidents Cleared in De Beque Canyon, 11 News website, 03/02/2010 

http://www.nbc11news.com/home/headlines/85942917.html 

Big Thompson Canyon Rock Slide, May 21, 2010 

Rock slide Closes Highway 34 in Larimer County (Colorado State Patrol online 

Blogspot, 05/21/2010 

http://coloradostatepatrol.blogspot.com/2010/05/rock slide-closes-highway-34-inlarimer.html

June 17, 2010 Rockfall incident, (one casualty), Estes Park, Colorado 

Falling rock in Estes Park kills Michigan teen - The Denver Post 06/18/2010 

http://www.denverpost.com/breakingnews/ci_15325900?source=rss#ixzz1oBpNmsET

Charges dismissed in rock-kicking incident that killed Kent County girl in Colorado, 

Grand Rapids News, (01/20/2011) 
44 

http://www.mlive.com/news/grand-rapids/index.ssf/2011/01/charges_dismissed_in_rockkick.html

Durango and Silverton Narrow Gauge Railroad Debris Flows, July 26, 2010 

Line Back Open after 3 Trains and About 1,000 Passengers Were Thwarted Monday, 

Albuquerque Journal, 07/29/2010 

http://www.abqjournal.com/main/2010/07/29/abqnewsseeker/705am-mud-rock slidesblock-durangosilverton-railroad.html

Carbondale/Redstone/Marble area debris flows, July 31, 2010 

The Crystal Valley is . . . Mudslide Central, The Crystal Valley Echo and Marble Times, 

(September 2010, vol. 7 n. 9 issue). 

Large mudslides Hit Redstone, Marble Area, Denver Post, 07/31/2010 

http://www.denverpost.com/breakingnews/ci_15649962 

Clohsey Lake debris flows, July 31, 2010, Chaffee County, San Isabel National Forest 

http://www.thedenverchannel.com/news/24496924/detail.html 

Jackson Mountain landslide, Highway 160 near Pagosa Springs, CO 

Landslide Mitigation and Highway Improvements Begin on U.S. 160 East of Pagosa 

Springs, High Beam Research news, 09/13/2010 

http://www.highbeam.com/doc/1G1-237078577.html

Emergency Plan in Place for Jackson Mountain Project, Pagosa Sun, 05/11/2011 

http://www.pagosasun.com/archives/2011/05May/051211/pg1jacksonmtn.html

Landslide mitigation and highway improvements suspended for winter on US 160 east of 

Pagosa Springs

http://www.coloradodot.info/news/2012-news-releases/02-2012/landslide-mitigationand-highway-improvements-suspended-for-winter-on-us-160-east-of-pagosa-springs 

El Paso County - Highway 24August 9, 2010, Rock Slide Hits Camper Trailer On Hwy. 

24, KRDO news station, Pueblo, CO, 08/9/2010 

http://www.krdo.com/news/24569017/detail.html

Redstone/Carbondale area, August 19, 2010 

Mudslides Close Hwy. 133 Near Redstone, Westbound Lanes of Hwy. 82 Near 

Carbondale (The Aspen times, 08/20/2010).

http://www.aspentimes.com/article/20100820/NEWS/100829997

CDOT reported costs of $34,000 for the August 19 event and there was estimated to be 

6000-6500 tons to be removed. (D’Wayne Gaymon, CDOT Region 3 written communications 

May 12, 2010). 

Non-copyrighted photos can be viewed on the USGS Landslide Program website: 

http://landslides.usgs.gov/learning/photos/colorado__u.s._/redstone__carbondale__marb

le_colorado_debris_flows_mudslides--july_31__and_august_19__2010

September 23, 2010 Potential Debris flows due to Fourmile Canyon, Colorado wildfire: 

Gov. Hickenlooper Issues Disaster Declaration for Fourmile Fire Burn Area in Boulder 

County 

Colorado Disaster Declaration and Press release issued April 4, 2011, by Colorado 

Governor Hickenlooper, which includes information on hazard losses from potential debris 

flows:

http://www.colorado.gov/cs/Satellite?c=Page&childpagename=GovHickenlooper%2FC

BONLayout&cid=1251590836028&pagename=CBONWrapper

Rock slide injury - On September 29, 2010, near Palisade
45 

Three cars hit each other, possibly trying to avoid the rocks that had fallen on the road – 

three people were hospitalized (9 News report, September 29, 2010). 

http://www.9news.com/news/story.aspx?storyid=155518&catid=222

The same story was reported by ABC News. (ABC News, September 29, 2010) 

http://www.thedenverchannel.com/news/25209538/detail.html

October 29, 2010 – Dillon, Colorado area rock slide 

Property Owners Investigating Cause of Dillon Rock Slide, Summit Daily News, 

01/27/2010. 

http://www.summitdaily.com/article/20100527/NEWS/100529848

Fourmile Canyon Fires, September 2010 

Boulder County Fourmile Emergency Stabilization Team Report

http://www.bouldercounty.org/live/environment/land/pages/4milefesteam.aspx

As a follow up, the area experienced two large debris flows in 2011. On July 7, as a result 

of a heavy rainstorm, four reported debris flows occurred at mile marker 8 in Fourmile Canyon. 

http://www.youtube.com/watch?v=vaqne-NMWOw

 On July 13, 2011, Six roads were closed due to debris flows including Four Mile Road 

and Gold Run at Dixon—areas which were highlighted in the 2010 Debris-flow Potential report 

(Ruddy and others, 2010). 

http://denver.cbslocal.com/2011/07/13/debris-flows-closed-roads-fourmilecanyon/#.T481f3rUn-Q.email

CDOT Website had many of their costs itemized, http://www.coloradodot.info/

CDOT Rockfall mitigation program funding and FASTER program funding: 

http://www.realaspen.com/community-content/161/Rockfall-mitigation-project-comingto-Highway-82 

Federal Highway Administration, http://www.fhwa.dot.gov/

December 22, 2010 Amtrak Train Blocked by Rock slide 

http://denver.cbslocal.com/2010/12/22/rock-slides-detour-train-traffic-throughmountains/ 

List of sources consulted by phone, email, or personal visit: 

Town of Redstone, Colo. 

City of Carbondale, Colo. 

 Planning, Engineering, Emergency Management Departments 

Pitkin County, Colo. 

 Planning, Engineering, Emergency Managements Departments 

Garfield County, Colo. 

Mesa County, Colo. 

Jefferson County, Colo. 

City of Glenwood Springs, Colo. 

Town of Estes Park, Colo. 

CDOT All Regions—7 offices

CDOT Geotechnical Engineering Department, Denver, Colo. 

Excel Energy, Denver, Colo. 

Flat Top Fuel, Meeker, Colo. 

Karolyn Wakefield, Assistant Manager—called April 25, 2011 

Domenico Trucking Company, Denver, Colo. 

Amtrak (The National Railroad Passenger Corporation) 
46 

Durango and Silverton Narrow Gauge Railroad, Durango, Colo. 

Manager Environmental Field Operations 

 Union Pacific Railroad

Indian Tribes:

Ute Mountain Ute Tribe 

Southern Ute Indian Tribe 

National Forests:

Routt 

Roosevelt 

Arapaho

White River

Grand Mesa

Pike 

Gunnison 

Uncompaghre 

San Juan

Rio Grande 

San Isabel

National Parks and Monuments 

Rocky Mountain National Park 

Colorado National Monument 

All Colorado State Parks 

Chaffee County Search and Rescue 

Colorado Geological Survey 

Colorado Division of Emergency Management, Centennial, Colo. 

Yeh and Associates

Colorado School of Mines, Golden, Colo. 

Appendix 3: Notes on Landslide Loss Investigations and Lessons Learned

The investigation of losses incurred by all types of landslides in Colorado for the year 

2010 was only partially successful due to the fact that many organizations and individuals 

queried did not know or chose not to disclose this information. CDOT, which is funded 

publically and is required to disclose the costs of all types of landslides which impact the 

transportation routes that are within its jurisdiction, was able to provide more information on 

losses than all other sources combined. CDOT maintains information posted online, employs 

public relations personnel who can assist with inquiries, and organizes their information in userfriendly databases and reports. The Forest Service provided loss data where information was 

available. However, much of the potential data from forest lands are not easily retrievable, are

kept by another entity, or are blended with other costs and not itemized. As mentioned 

previously, the vast tracts of public land that exist in Colorado under different jurisdictions 

generally preclude an accurate accounting of all the landslide occurrences on these lands, except 

where they effect outdoor activities, access roads, or threaten the built environment. The 2010 

Clohsey Lake debris flows described in this report are a good example of the type of landslide 

event that the Forest Service becomes directly involved in, as they are primary jurisdictional 

organization. 
47 

Much of the city and county data was either not itemized or was not retrievable. Many 

cities and counties have emergency-management policies that are currently available to view, 

either online or at the county offices, including contingencies for landslide hazards; however, 

costs or dollar losses for particular years or any aggregate lengths of time, are usually not 

available. 

Trucking companies and businesses located along landslide-caused detour routes stated 

that their businesses were affected, either positively or negatively, but did not provide dollar 

losses or gains. This type of loss is very important in assessing the effects of landslides, although 

they are classified as indirect losses. Nevertheless, such losses or gains would be difficult for 

most businesses to estimate.

The State of Colorado has clearly identified and planned for landslide hazards, usually in 

the context with other geohazards such as swelling soils, mine subsidence, and general erosion. 

In addition, these geohazards are generally linked with meteorological hazards such as hail, 

lightning, flood, and tornadoes—not because they are similar in nature, but because they have all 

been shown to be natural hazards that have effected Colorado in the past. Unfortunately, 

landslides, debris flows, and other types of landslides associated with flooding are not usually 

evaluated separately from the damages caused by the floodwaters themselves. Funding for the 

reduction of landslide hazards is authorized in cities and counties primarily for the maintenance 

of transportation corridors, evaluation of new-construction site plans for hazards, and personal 

safety. Landslide-mitigation policy varies from county to county in Colorado, is not 

standardized, and is mostly in conjunction with development planning and roadway planning and 

maintenance.

Finally, one of the main reasons that landslide-cost data are difficult to find is that losses 

due to landslides are not covered by homeowner or commercial insurance. Insurance companies 

are usually a good source of loss data for most hazard types, except for landslides. The main 

reason that insurance companies do not cover landslides is that there are no reliable data on 

landslide history, locations, and costs, although some areas of the United States have published 

landslide-susceptibility maps. However, landslide-susceptibility maps do not usually include 

probability or risk-assessment elements. The lack of insurance for landslides is a situation that 

becomes a circular pursuit of information that deals with too many unknowns, and the unknowns 

are not easily identifiable by any cost-effective approach that states and municipalities can justify 

in their budgets. There is little information upon which to base premiums and the situation is 

currently at a stalemate. There are communities that have implemented Geologic Hazard 

Abatement Districts (GHADs), which is an attempt at landslide self-insurance for a small area, 

for example, a housing development or special district. However, GHADs still require landslidehazard information for the area in question, in order for them to function. As of 2011, there were 

40 GHADs in the State of California (Patricia E. Curtin, Morgan Miller Blair, Law Corporation 

and American Association of GHADs (written commun., 2011, http://www.ghad.org/) 

The following is a list of general information that will assist those performing future loss 

studies: 

1. Data on highway and public utility repairs are generally (but not always) available: 

• Past data are generally labor intensive to retrieve; 

• Loss data are sometimes absorbed into general maintenance costs, where it 

becomes cost-of-maintenance data rather than loss data. 

2. Data are not generally available for nondisaster event recovery periods: 
48 

• Disaster payout for direct cost replacement and repair may be available from 

Federal and State emergency-management agencies as well as local governments; 

• Loss records kept by emergency management agencies are generally limited to 

eligibility for disaster assistance; 

• Concerted efforts to conduct studies by devoting personnel, time, and funding 

can generally be fruitful; however, they take long periods of time to compile because loss 

data usually become available only after periods of several months and, in some cases, 

many years. A USGS report on landslide losses from the Nisqually, Washington, 

Earthquake of 2001 (Highland, 2003) is one exception, as resources were allocated to 

compile an extensive report within a short period of time. In that case, there was a 

Federally declared disaster and costs were to be reimbursed on a case-by-case basis, 

tracked by both Federal and local officials.

3. Recordkeeping of loss data is done most extensively by local governments in urban 

areas where ordinances require permits for reconstruction: 

• Those records that are kept are typically only of direct costs; 

• The records are associated with issuance of rebuilding, repair, or grading 

permits associated with landslide damage. 

4. Where recordkeeping exists, it is not standardized: 

• Categories of direct costs (for example, slope stabilization, structural repair, and 

so forth) are not generally separated from each other during recording; 

• Secondary direct costs, such as geotechnical investigations for remediation, 

mortgage-company losses on destroyed structures, and so forth, may be kept by different 

entities than those who keep the direct costs. 

• Indirect-cost data (such as interruption of business and other economic 

consequences of landslide damage) may only be available by post-event economic 

surveys and analysis by the business community. 

5. Summary conclusions about landslide loss data: 

• It is very labor intensive to retrospectively collect loss data from any of the 

identified sources. The use of information technology in future recordkeeping may 

provide a practical means of retrieving landslide loss data if the information is coded as it 

is recorded. A considerable amount of time, money, and personnel would have to be 

devoted to loss-data collection, at least until methods are streamlined and become routine. 

• Media sources of cost data are sometimes incomplete and not systematic or 

always reliable. However, many media outlets publish special reports from time to time 

that review data and knowledge about an incident, which is a boon to researchers trying 

to put together disparate sources of information 

• Due to copyright issues and privacy concerns, private consulting firms are not a 

practical source of extensive landslide cost data. However, these sources should not be 

ruled out, as permission to use private and copyrighted data is sometimes granted, or in 

some cases can be purchased for a fee. Also, public entities (such as CDOT) who contract 

with private-sector geotechnical companies for landslide work, for example, are required 

to disclose the bidding history of each project and how much the private companies were 

paid. Such disclosure is a good source of information on landslide costs.

• A standardized approach to landslide-loss inventory would reduce the cost and 

improve the usability and availability of landslide-loss information. However, previous 

attempts at implementing a standard landslide-inventory collection or cost-data 
49 

acquisition method for all states, for example, have only been partially successful, given 

that each of the 50 States has the freedom to implement their own ways of dealing with 

natural hazards.