and the upstream pool raised to stabilize an up-
1. Existing Nine Mile, Dickey, Fort Kent and
stream ice cover, or increase ice storage capacity,
Allagash DCP stations.
or move the ice jam location further upstream.
2. New sites at Big Black River confluence,
On the other hand, increased output flow can
above Big Rapids, or Priestly.
force an early run of the ice below the project, if
3. Bridges (consider one or all sites).
the breakup has begun or is imminent. Two con-
ditions are paramount in the use of operational
Aroostook River
techniques to control ice jams, namely that there
WashburnWade area
is sufficient capability in flow control to achieve
An ICS or a jam enhancement method should
the desired results, and that no adverse effects
be used at Donnelly Island reach in Wade, such
will be caused at undesirable locations either up-
as:
stream or downstream from the project.
1. Overflow weir (e.g., at Gardner Creek Road
boat launch).
Early warning of ice jam events
2. Cribsspur dikes.
One consequence of the field study was confir-
3. Modified booms.
mation of the value of the experimental ice mo-
4. Excavation.
tion sensor installed at Nine Mile bridge for early
warning of ice breakup. Such ice motion sensors
Crouseville area
would complement existing forecasts by the Na-
Road alterations or dikes in the village, or both,
tional Weather Service and St. John River Flood
should be considered as follows:
Forecast Center to warn of ice breakup. An early
1. Improve existing bypass channel on left
warning could allow state and local officials to
bank.
take appropriate action to reduce the effect of ice
2. Raise low spot of Route 164 east of village
jams.
by 5 ft.
3. Conventional dike at same site.
APPLICATION TO THE
Fort FairfieldCaribou dam reach
ST. JOHN RIVER BASIN
An ICS or a jam enhancement method should
The field observation program of the 199192
be used upstream of town. Sites to evaluate are
winter has allowed us to identify general areas
the island area approximately 2000 ft upstream of
where direct ice control could be beneficial. The
the Route 1 bridge and the Haley Island area,
possible methods applicable to each area are list-
which is about 5 miles upstream of the bridge.
ed below. We also recommend creation of an ear-
Methods to evaluate include:
ly warning network as part of any future ice jam
1. Weir, possibly with bypass channel.
mitigation plans.
2. Excavation of islands.
3. Cribsspur dikes with or without excavat-
St. John River
ing.
AllagashDickey area and upper St. John reaches
4. Modified booms.
In addition, an ICS from 1/4 to 3 miles upstream
ICS or jam enhancement upstream of Dickey. Sites
that should be considered include St. Clair Island
of Caribou's dam should be built. Potential meth-
above Big Rapids, the confluence area with Big
ods include:
Black River, Priestly Deadwater reach, and Seven
1. Timber cribs.
Islands reach. Methods to evaluate are:
2. Spur dikes.
1. Weir with gate for open water canoe pas-
3. Modified boom.
sage.
Conventional dikes should be constructed in the
2. Excavation of St. Clair Island.
village and operational changes at Tinker Dam
3. Cribsspur dikes.
should be considered.
4. Modified booms.
The existing early warning network should be
Grand Isle. At this location, conventional dikes
improved by adding ice movement sensors. This
should be considered, as should operational
can be done by the following:
changes at Grand Falls Dam. In addition, the ear-
1. Using existing DCP stations at Washburn
ly warning network should be improved by in-
and Masardis.
stalling ice motion detection sensors at the fol-
2. Developing new sites above and below the
lowing places:
dam in Caribou.
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