Boundary County

All Hazards Mitigation Plan


Section 9

Hazard Profiles – Winter Storms

Definition, Description and Potential Damage  Winter storms vary widely in size, duration, and intensity, but they are generally characterized by low temperatures and blowing snow. These storms may impact a single community or a multi-state area. They may last hours or days, drop a small amount of snow or blanket an area in wet snow and ice.

A severe winter storm is defined as one that drops four or more inches of snow during a twelve hour period, or six or more inches during a twenty-four hour span. A blizzard is a winter storm with winds exceeding thirty-five miles per hour and temperatures of 20° F or lower. Strong winds can lower the effective temperature through "wind chill." An ice storm occurs when water freezes immediately on contact with the ground, structures, and vegetation.  The LEPC estimates that Boundary County experiences at least one severe winter storm every year.

The principal hazards associated with severe winter storms are:

·                    Snow and/or ice accumulation

·                    Extreme cold

·                    Significant reduction of visibility

As frequently experienced in Boundary County, especially in the higher elevations, heavy snow and/or ice can block roads, break power lines, topple trees, and cause flooding, landslides or avalanches. Trapped motorists may be stranded for prolonged periods and may suffer injury or death if not prepared.  Casualties may result as unfit residents attempt to dig out their homes and driveways.  Exhaustion or heart attack is the second most likely cause of winter storm-related deaths. Power outages can aggravate the extreme cold, leaving residents and livestock in the cold and dark for days or threaten the safety of people dependent on electricity for needed medical equipment.  

In Boundary County, blocked roads and limitations on access to emergency services is a concern.  Communities, such as Porthill, the Moyie River downstream from the Good Grief resorts and Eastport are at least 25 miles and at least 50 minutes from the nearest hospital.  Road conditions can thwart efforts to get the seriously ill or injured to needed services.  In addition, motorists who are ill equipped for road conditions may get stranded or cause accidents.  Accidents may contribute to roadblocks and access problems for emergency service needs.

Although there are no documented cases in Boundary County, extreme cold during winter storms can lead to casualties, both directly, through hypothermia, and indirectly. Hypothermia is a reduction of the body's core temperature due to prolonged exposure to cold. It is not always fatal but can produce long-term ill effects in survivors. The elderly are particularly at-risk. Frostbite (physical damage to bodily tissue from exposure to extreme cold) is a secondary risk that can also cause permanent damage.

Indirectly, extreme cold can lead to casualties through improper use of makeshift heaters, such as charcoal briquettes, in an enclosed space. Many fuels produce carbon monoxide that can lead to asphyxiation and may cause structural fires if untended or out-of-control. Fire control may be hampered by a freezing water supply and reduced accessibility.

Cold may persist long after the "storm" passes, complicating response and recovery functions.  Blowing snow and reduced sunlight during winter storms can make travel, both walking and driving, dangerous. Transportation accidents (automobile and other vehicles) are the leading cause of death during winter storms.

The impacts of a major storm may persist long after the event.  Heavy snow can also cause structural damage to homes and businesses when the weight of snow causes roofs to fail. This is a common problem in Boundary County during major snow events.  Recovery may take months when extensive property and economic damage has occurred.

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Severe Winter Storm Past Hazard Events and Risk  The occurrence of severe winter storms is to a large part dependent on broad climatic trends. These trends are difficult to forecast and the assumptions underlying projection of future events are subject to intense debate.  It is consequently difficult to generate any hard estimates of future storm frequency or intensity.   Boundary County is rated as "Moderate Snowfall" or "Heavy Snowfall" by FEMA.

  Boundary County experiences a “severe winter storm” at least once every year.  The areas most impacted are the communities of Trout Creek, Porthill, Moyie River Road, and East Port.

Boundary County experienced federally declared disaster events in February 1996 and in November 1996 through January 1997.  The winter of 1996 through 1997 was considered a record year for snowfall and heavy spring rain in Boundary County.  In November 1996, Boundary County was declared a disaster area when many roofs on buildings in the area collapsed or came dangerously close to collapsing from the usually heavy snow.  The Idaho National Guard was called on to assist in snow removal from most of the downtown Bonners Ferry city businesses and City Hall.  The Guard also assisted in removing snow from other buildings in the county, such as public schools.

LEPC Relative Risk Rating  In the LEPC relative risk rating of hazards, Winter Storm was given a moderate risk rating.  The LEPC estimates that, on the average, Boundary County experiences a “winter storm” somewhere in the county once a year, but most snow storms are not considered to be emergency incidents.  Storms may cause temporary road closures, school closures and delays.  Few injuries or illnesses are likely to occur during a severe winter storm event and few properties can be expected to be destroyed.  However, many properties will be damaged, and environmental resources will be damaged (with short-term recovery possible).   A single event will usually have a low direct cost but will have a high indirect cost. There have been no recorded serious events since 1996-1997. 

Highly Vulnerable Critical Facilities  The LEPC identified the following “ “critical facilities” as highly vulnerable to winter storms:

Black Mountain repeater services is the primary repeater for area law enforcement and most federal agencies.  This is also the location of the radio and television translators.

Verizon Communication also houses a structure on Black Mountain for the Boundary County phone network.



1.         Develop and update enforceable standardized building and planning codes.  Give special emphasis adequate roof load-bearing capability.

Lead Agency:               Boundary County Building and Planning

Supporting Agencies: LEPC, Boundary County Office of Emergency Management, Idaho Department of Transportation, private property owners, property owner associations, and interested community groups

When:                          Annually

Resources/Funding:       Annual agency budgets


1.         Educate the public on load-structured failure during snow events.

Lead Agency:               Boundary County Building and Planning

Supporting Agencies: Boundary County Sheriff’s Office, LEPC, Idaho Department of Transportation, private property owners, interested community groups

When:                          One year and then annually

Resources/Funding:       Annual agency budgets

2.         Develop and distribute information about building regulations and conduct private structure inspections.

Lead Agency:               Boundary County Planning and Zoning

Supporting Agencies: Boundary County Building and Planning Department and other county, state and federal agencies

When:                          One year

Resources/Funding:       Federal and state grants, local budgets


1.         All winter storm incidents should be reported to the Office of Emergency Management.

Lead Agency:               Boundary County Office of Emergency Management

Supporting Agencies: Local fire districts, local highway districts, LEPC

When:                          Ongoing

Resources/Funding:       FEMA and state disaster mitigation funds, county budget, fire and highway district budgets

2.         Plan for and maximize emergency access to all public and private property during winter storm incidents.

Lead Agency:               Boundary County Highway Districts

Supporting Agencies:    Boundary County Sheriff’s Department, local highway Districts, Idaho State Department of Transportation, Planning and Zoning

When:                          Two to five years

Resources/Funding:       FEMA grants, local and state budgets

3.         Support initiatives to provide effective public communication during winter storm incidents.

Lead Agency:               Boundary County Office of Emergency Management

Supporting Agencies:  Natural Resource and Conservation Service; US Geological Survey, National Weather Service, and local elected officials

When:                          Two to five years

Resources/Funding:       Agency budgets

4.         Identify and prioritize existing problems which could impact critical infrastructures.

Lead Agency:               LEPC

Supporting Agency:      Idaho Transportation Department, and County Road and Bridge Departments

When:                          Ongoing

Resources/Funding:       Local funding source