EP 1110-2-11
30 Nov 94
Figure 2-1. Ice jam flooding
f. Although the actual time period of flooding may be short compared to open water flood events lasting days to
weeks, significant damage can result. The winter weather conditions often prevalent when ice jams occur also add to the
risks and damages associated with ice jam flooding.
2-3. Ice Jam Flood Losses
a. Ice jam flooding is responsible for loss of life, although the number of fatalities in the United States is con-
siderably less than non-ice jam flooding. In the last 30 years at least seven people have died as a result of ice jam
flooding. Six of the deaths were attributed to rescue attempts; the other death occurred from injuries sustained when a
basement wall collapsed due to pressure from flood waters and ice.
b. Ice jams in the United States cause approximately 5 million in damages annually, including an estimated
million in personal property damage and million in operation and maintenance costs to USACE navigation, flood
control, and channel stabilization structures.
c. Ice jams suspended or delayed commercial navigation causing adverse economic impacts (Figure 2-4).
Although navigational delays are commonly short, they may result in shortages of critical supplies, such as coal and
industrial feedstocks and large costs from the operation of idle vessels (USACE 1981). Ice jams sometimes cause dam-
age to navigation lock gates. For more detailed information on the effects ice jams have on navigation and the range of
strategies to mitigate the effects, see "Winter Navigation on Inland Waterways" (USACE 1990).
d. Ice jams also affect hydropower operations, causing suspension of hydropower generation due to intake
blockage, high tailwater, the necessity to reduce discharge, or damage to intake works (Figure 2-5). Lost power revenue
due to such shutdowns can be substantial.
e. The presence of an ice jam can result in scouring and river bed and bank erosion that may lead to bridge or
river bank failure (Figure 2-6). Ice jams can damage stream channels and improvements so that overall vulnerability to
flooding is increased. Riprap can be undermined or moved out of place. Ice-jam-related damage to river training struc-
tures costs millions of dollars each year.
2-2
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