a. Locations of booms.
b. Ice boom at Prescott, Ontario.
c. Iroquois control structure.
Figure 7. Ice booms on the International Section of the St. Lawrence River.
made of double rows of 2-ft-diameter plastic
the International Section of the St. Lawrence
pipe was installed on the Pasvik River, in the
(Perham 1974, Power Authority of the State of
forebay area of the Hestefoss power plant on the
New York 1970, Bryce 1982*).
Russian border with Norway. The plastic booms
More recently, ice booms have been used suc-
formed part of an elaborate ice control system
cessfully in northern Quebec during construc-
involving stone groins and timber booms. The
tion phases of the 10,300-MW James Bay Project
system was designed by Norwegian engineers
on the La Grande River. Presently, there are no
ice booms in use, however.† On the 5300-MW
to promote an ice cover during the plant's con-
Churchill Falls Project in Newfoundland, a
struction (Kanavin 1970). The plant is now oper-
boom promotes ice cover formation in Jacopie
ated by the Russians and little is known about
Lake, above the forebay. The boom also helps
the recent performance of the booms (Roen and
prevent jams in a channel constriction down-
stream at breakup (Atkinson and Waters 1978).
Ice management on the Lule River in north-
Ice booms have been used upstream of hydro-
ern Sweden has similarities to methods used on
power dams in northern Europe, particularly in
the upper St. Lawrence. Upstream of the Vittarv
Norway and Sweden. In the late sixties, a boom
power station, a 2000-ft-long boom spans the
Lule River. Similar to the Beauharnois booms, a
330-ft-wide central section allows floes to pass
* Also, personal communication with Dan Herrmann of
and contribute to the ice cover progression in a
NYPA, April 1994.
narrow reach downstream. The gap is closed
† Personal communication with Donald Carter, ice consult-
once a cover has formed in the narrow reach. If
ant for Hydro Quebec, July 1994.