Ice Jam Flooding

Kathy Simpson

The winter of 2017 was a season of wild temperature fluctuations in the Northeast.

From late December into early January, a strong Arctic air mass resulted in a brutal cold snap with temperatures that hovered just degrees above zero in most areas and dipping well below zero in northern regions. A severe blizzard followed, dumping over two feet of snow. Then, in mid-January, temperatures climbed into the 60s, and all the snow and ice that had accumulated began to thaw. With the thaw came ice jams – and extreme flooding in many areas.

What Are Ice Jams?

Ice jams are large chunks of floating ice that form on a river and block its flow. They occur when warming temperatures and heavy rains cause snow and ice to melt very quickly. As river waters rise, the surface layer of ice breaks into chunks that are carried downstream by the rushing waters, forcing the ice chunks to lodge against one another, near bridges, where streams meet, between narrow passages, and around bends in the river. Just as a traffic jam prevents cars from moving through, an ice jam effectively dams the river’s natural flow. With nowhere else to go, the water behind an ice jam can flood the surrounding area, putting nearby homes, businesses and people in peril.

That’s what happened along many Northeast rivers during the January 2018 thaw. In Swanton, Vermont, an unusually large ice jam on the Missisquoi River became lodged in town, flooding about 1.5 miles of state highway and several homes, and prompting evacuations. In Plattsburgh, New York, high water caused by a large ice jam along the Saranac River flooded about 50 homes. In Kent, Connecticut, a state of emergency was declared due to ice jams as thick as 12 feet along the Housatonic River. In Hallowell, Maine, an ice jam along the Kennebec River caused floodwaters to freeze around vehicles in a town parking lot.

Where and When Ice Jams Are Most Common

Ice jams can form wherever winter is cold enough to cause rivers to freeze – mostly in the Northeast, the Midwest and Alaska, and mostly during early spring months when warming temperatures cause melting snow and ice that raise the level of still frozen rivers and streams. But as evidenced in January 2018, ice jams can occur anytime winter conditions are right.

While most ice jams occur when a thaw causes surface ice to break up, they can also occur when extremely cold air causes open water to rapidly freeze up. Freeze-up jams are more typical in early winter and usually result in little if any flooding. Break-up jams are more destructive, causing flooding that has been known to push entire houses off their foundations.

Mitigating an Ice Jam’s Effects

Once an ice jam is formed, there is little to be done about it until it melts enough to break up. However, afflicted areas have been known to call in boats to break up the ice, or use heavy equipment to try to pick up the ice from shore. Where ice jam flooding is common and causes serious flooding, municipalities may invest in ice-control structures. A relatively low-cost approach is to install big cement pillars at 10 to 15 foot intervals spanning the river that effectively catch and hold the biggest slabs of ice upstream of town where they will do no harm.

But even this can be a prohibitive proposition where ice jam flooding is infrequent. For most people who live near a river that has the potential of forming ice jams, mitigation is the same as for any other kind of flood.

What to Do If An Ice Jam Occurs Near Your Home

Ice jams can cause flooding with little or no warning. If you live near a river and conditions are ripe for an ice jam:

  • Monitor the river’s ice conditions and water level.
  • Follow emergency management postings on social media, and listen to local news outlets for flood warnings and states of emergency. Sign up for emergency text alerts.
  • Plan an emergency escape route in advance.
  • Develop a calling tree of neighbors to notify if a flood emergency occurs so everyone can safely escape.
  • Have ready an emergency kit complete with supplies you’ll need to sustain you and family members should you need to leave your home. Your kit should include water, flashlights, batteries, a backup cell phone charging system, food, blankets, and dry clothes.
  • If flooding is predicted, shut off your water, gas, furnace and electrical services if you can do so safely. Leave home if evacuation orders are issued, or if floodwaters near your home.

If your home is flooded, follow these best practices when you return home:

  • Check for structural damage, and contact utility companies if you suspect damage to water, gas, electric, and sewer lines.
  • Take photos or videos of the state of your home to share with your insurance company.
  • Wear rubber gloves to avoid contaminants when cleaning up and removing water-damaged contents.
  • Boil water until authorities declare the water supply safe.
  • Contact your insurance company as soon as possible after a flood. Advise your insurance representative of the state of your home and any repairs that may be required. Keep records of the damage and all conversations.

About Flood Insurance

Many people believe their homeowners or rental insurance policy covers flood damage when it usually doesn’t. For coverage, you must purchase a separate flood insurance policy. Most flood insurance policies are purchased through an insurance company or an agent that participates in the National Flood Insurance Program. In fact, if you live near a river and have a mortgage, your lender will likely require coverage. Your policy takes effect 30 days after you sign the contract, so be sure to purchase your policy before the winter season arrives.

Auto insurance does cover flood damage to your car if you have comprehensive coverage on your policy. Comprehensive coverage is likely required if you’re financing your vehicle, but is otherwise an election. If your car is paid for and you live in a flood-prone area, the investment in a higher premium will likely pay off if your car if damaged or declared a total loss due to a flood.

The Hartford offers NFIP coverage to AARP members. Learn more or request a quote.

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