of events and probably reflects warmer-than-average temperatures over much of the continental United States along with
lower-than-normal snowpack. Most of the ice jam information was obtained through daily bulletins from the National
Weather Service (NWS). Other sources of information include Corps and CRREL personnel and Internet articles.
When and where did ice jams occur in 2002?
During WY 2002, over one-third of the ice events (34%) occurred during May in the state of Alaska. December
accounted for 22% of events, and April and February followed with 16 and 13 percent, respectively. November accounted for
3 percent; January and March each experienced their share of events at 6 percent each (Fig. 2).
Eleven states, including Maine, Colorado, and Alaska, were affected by
ice jams during WY 2002 (Fig. 3). Alaska had 16 events (Fig. 4), the
November
highest number of jams in a state this year, while Minnesota, Maine, and
5%
April
Nebraska each had 4, 3, and 2 ice events, respectively. The remaining states
24%
were affected by only one event (Fig. 5).
Maine's three jams were all similar: small freezeup jams that occurred
December
32%
around mid-January and lasted through most of February. Two of the three
jams were reported on the St. John River and one was located on the
March
10%
Aroostook River. These small jams posed no threat to local communities
(NWS 2002a).
The four jams in Minnesota appear to be unrelated in their timing.
January
February
These jams occurred in early December, late December, late February, and
10%
19%
mid-April. Two of the jams occurred on the Mississippi River at Fort
Ripley, while the other two were on the Red Lake River and on Mille Lacs
Figure 2. Months in which 2002 ice jams
Lake. The ice event at Mille Lacs was an ice-out event, which occurred in
were reported.
April when westerly winds aided in
the lake ice-cover breakup and
pushed huge chunks of ice onto
shore. The ice was forced into 20-
foot-high piles, bringing boulders
onto lawns and destroying decks
and docks (Mille Lacs Messenger
2002).
At the beginning of March, a
rain event in northern New
England caused two minor breakup
jams: one on the Israel River in
Lancaster, New Hampshire, and
the other on the Waits River in
Bradford, Vermont.
Alaskan ice jams
Alaska had the earliest
reported ice jam this season on 8
November 2001, when the Susitna
River at Montana, Alaska, froze
during a below-normal cold spell
Figure 3. Ice jam locations in the lower 48 states during WY 2002.
and backed up water (NWS 2001a).
The remaining Alaskan ice jams formed during December (two freezeup jams) and April and May (13 breakup jams).
At the beginning of December, colder temperatures caused one major freezeup jam on the Kenai River where water rose
six feet (NWS 2001b). Near the end of December warmer weather caused an increase of water flow, causing the North Fork
of the Anchor River to release ice and cut off access to a few homes (NWS 2001c).
2
ERDC/CRREL TN-03-1
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