County updating Multi-Hazard Mitigation Plan

Crook County has begun the process of updating its Multi-Hazard Mitigation Plan, a document that details the range of natural hazards that affect this region and identifies ways to lessen the disasters they could cause. Public participation is needed to identify the hazard mitigation projects that would most benefit the county, aiming to tackle such issues as education and awareness, property protection, prevention and natural resource protection.

Further details about the plan and the input needed to help the county update it can be found in this week’s issue of the Sundance Times. The plan identifies 17 natural disasters that could occur within the county, 13 of which are considered to be significant and potentially life-threatening.

Below are details of the disasters, including the benchmark examples used within the plan to evaluate their risk:

 

  • Dam failure is the uncontrolled release of impounded water, resulting in downstream flooding that can affect life and property; it can be caused by flooding, blockages, landslides, earthquakes or human interventions such as vandalism, terrorism or improper maintenance and operation. Eight dams within the county are considered a high or significant risk, which presents the possibility of dam failure flooding with a potential of $1 million in damages and loss of life.

 

  • Droughts are one of Wyoming’s most costly weather-related disasters and indirectly kill more people and animals than the combined effects of hurricanes, floods, tornadoes, blizzards and wildfires. A multi-year drought within the county could cause a loss of around $26.2 million.

 

  • Only two earthquakes have been recorded within or near Crook County with enough intensity that they could be felt noticeably indoors and the probability of a worst-case event occurring in the future is just 2 percent in 50 years. Should an earthquake of fairly high intensity occur, however, it could damage five percent of the county’s buildings, causing $4.8 million in damages.

 

  • Expansive soils, which can have significant impacts on roads, bridges and buildings, exist in the western part of the county and, according to the plan, Crook County has over $3.5 million in buildings on or over expansive soils. This hazard, while currently only likely to affect a small number of individual structures and roads, is an important consideration for mitigation efforts in future development.

 

  • Flooding is one of Wyoming’s more significant natural hazards and can cause millions of dollars in damage in the space of hours. Sundance has the greatest risk of flood damage with the most structures within the one percent annual flood zone, causing a potential total loss of $830,503.

 

  • Crook County is not within “Hail Alley,” the southeast corner of Wyoming battered by more hailstorms than any other part of the United States, but has still been affected by damaging hail storms and is expected to experience them in the future at a recurrence interval of 2.9 years. Based on storm damage from a 1980 storm, in which golf ball-sized hail devastated Moorcroft within 20 minutes and damaged schools, houses, businesses and vehicles, future hail storms could cause $7.7 million or more in damage.

 

  • Hazardous materials are meanwhile said to pose an unreasonable risk to health and safety of emergency personnel, the public and the environment if not properly controlled. Spills will continue to occur, both in Wyoming and across the nation, and some local facilities contain extremely hazardous substances that could pose significant threats, such as radiological material transported on county roads and the railroad.

 

  • The risk of landslides, another common geologic hazard across the state, is difficult to determine thanks to poor historic data, but an event is likely to affect transportation corridors, reservoirs and some structures within the county. There is also a small possibility of smaller creeks becoming dammed, creating flash floods.

 

  • Land subsidence, often associated with roof collapse in mined-out areas and defined as the sinking of land over manmade or natural underground voids, may in the future affect development near the seven abandoned coal mines, 15 abandoned hard rock mines and three uranium mines within the county. The abundance of soluble gypsum in the county, according to the plan, could seriously compromise the recently completed Bakken Pipeline project and other initiatives in the area, should subsidence occur.

 

  • Lightning may be less significant than other hazards defined within the plan, but remains a danger to anyone caught in an exposed area during a thunderstorm, such as outdoor enthusiasts, hikers and climbers. Damaging lightning events occur every 3.3 years in the county and have the potential to also cause wildland fires.

 

  • Wyoming lies just west of “Tornado Alley;” though fewer intense tornadoes occur here than in neighboring states, they remain a significant hazard and Crook County ranks fourth of the 23 Wyoming counties for reported tornado damage. Tornadoes are expected to occur every 2.2 years on average; the worst-case historic tornado caused $2.15 million in damages.

 

  • Of all the fires in Wyoming, over 50 percent involve wildland areas. With 2012 proving a record year for wildfire and drought increasing the probability of occurrence and the potential for larger and more destructive fires, Crook County has $184 million in building value alone potentially at risk to fires.

 

  • Severe winter storms may be less violent than their summer counterparts, but they affect far more Wyoming residents. Crook County is expected to continue to experience damaging winter storms almost every year. Based on the worst-case regional event in 1984, the dollar impact could exceed $37 million, enough power lines could be toppled that emergency intervention would be required, significant property damage could occur and the livestock industry could lost 15 to 20 percent of its inventory.  Injury and death is likely during storm-related vehicle accidents, while life safety is a concern for motorists, outdoor enthusiasts and stranded ranchers.

 

  • Among the hazards considered present but not likely to have significant effects within the next 100 years, or that have not had a historical impact on property or life, windstorms were determined to be uncommon. Windblown deposits, such as areas of shifting silts and sands that can encroach on development and agricultural areas, are located in the northwest and southwest but are not known to have caused problems. Volcanic activity from Yellowstone could cause an immense eruption, but is not considered likely within the next 20,000 years.

 

To offer input at any time until the plan is adopted, you can either attend one of the upcoming meetings or contact Crook County Homeland Security at homelandsecurity@crookcounty.wy.gov or 283-2390 or Barb Beck at barbbeck@bresnan.net or 406-446-3628. Information about the planning process and draft documents are also available on the county website at www.crookcounty.wy.gov