Typically the start of an ice jam occurs after a long period of cold in which portions of a river or stream freeze and then temperatures or water levels fluctuate causing the ice to break into chunks. As these ice chunks move downstream they can become jammed at bridges and other constricted locations along a river and stream. The ice can begin to accumulate and create a dam. Low lying upstream areas may then begin to experience flooding due to the water rising behind the dam. Downstream areas can also be affected if the ice jam releases, which can cause a sudden surge of water and ice and cause flooding to low lying areas adjacent to the river or stream.
According to the U.S. Army Cold Regions Research and Engineering Laboratory (CREEL) ice jam database, ice jams in New Hampshire usually occur between January and March. Since 1835, ice jams have affected communities and their residents throughout the state. Some communities have been affected over the years by ice jams more than others but the risk for ice jam applies statewide.Are Ice Jams considered in FEMA’s Floodplain Maps?
No, ice jams are not considered in mapping floodplain areas on FEMA’s Flood Insurance Rates Maps. Only natural flow is considered on these maps. Ice jams can be unpredictable and happen very quickly. It is important for property owners near rivers and streams to know that flooding can occur outside the mapped floodplain areas due to various and conditions and circumstances including ice jams.What is Flood Insurance and does it cover Ice Jam Flooding?
Flood insurance is a way for property owners, renters, condominium associations, and businesses to insure their property (building and/or its contents) against flood loss. Flood insurance through FEMA’s National Flood Insurance Program (NFIP), is available to all residents, business owners, and condominium associations located in a community that participates in the NFIP. Currently in New Hampshire 220 communities participate in the NFIP with 16 communities that do not. Flood insurance is available in the NFIP communities whether the property is located in a floodplain or outside of the floodplain.
Flood insurance will cover losses for eligible structures due to the result of a flood, which can include ice jam flooding. The NFIP defines flood as:
A general and temporary condition of partial or complete inundation of two or more acres of normally dry land area or of two or more properties (at least one of which is the policyholder's property) from:
- Overflow of inland or tidal waters; or
- Unusual and rapid accumulation or runoff of surface waters from any source; or
- Mudflow; or
- Collapse or subsidence of land along the shore of a lake or similar body of water as a result of erosion or undermining caused by waves or currents of water exceeding anticipated cyclical levels that result in a flood as defined above.
Everyone lives in a flood zone, whether you live in a low-, moderate- or high-risk flood area. Floods can occur even when a property is not located near water and can be caused by storms, melting snow, hurricanes, ice jams, water backup due to inadequate or overloaded drainage systems. It is also important for property owners to know that homeowners insurance does not cover losses that are defined above as “flood.”
Property owners that are located in a mapped floodplain area and have a federally-funded mortgage or loan will be required by their lender to carry flood insurance for the life of the mortgage or loan. Property owners that are not located in a floodplain area or for those located in a mapped floodplain area but do not have a lender requirement are not required by their lender to purchase flood insurance. Approximately 25 percent of flood insurance claims were for structures that were located outside of the mapped floodplain areas. Flood insurance premiums for properties outside of a mapped floodplain area are lower in cost due to the lower risk of flooding.Can a Property Owner only get Flood Insurance during Ice Jam season?
No, flood insurance is a one-year policy and there are certain restrictions in cancelling a policy. Also, there is a 30-day waiting period before a flood policy goes into effect. There are some exceptions in which a waiting period does not apply but that mainly includes when a lender is involved.
Flood insurance is meant to be a long-term way of managing risk. By maintaining flood coverage only during ice jam season, property owners run the risk of not having flood insurance coverage for flooding that may occur from ice jams or other sources of flooding outside of a typical ice jam season.
For more information about flood insurance, please talk to your insurance agent and visit
FEMA’s FloodSmart web site at: www.fema.gov/national-flood-insurance-program