Download Geographers believe that originally the4 area that is now Lough

Lough Allen
Geographers believe that originally the area that is now Lough Allen
was once just a valley. During an Ice Age (not the last one) a glacier
deposited stones and rocks at either end of the valley and blocked up
the valley. Over the years this area
filled up with water from rain, streams
and rivers and became a lake. During this
period it is thought that the waters of
Lough Allen flowed into the Altantic
Ocean at Sligo. This passage to the
Atlantic Ocean became closed off,
possibly by a volcanic eruption and the
waters of Lough Allen began flowing
south.
At its longest the lake is 17.7km (11
miles) long and at its widest it is 4.3km
(3 miles) wide.
The
waters
from
Lough
Allen
once
flowed
into
Sligo Bay
Between 1935 and 1937 the E.S.B
built the Ballinatra sluice gates where
the Shannon River exits Lough Allen
near Drumshanbo. These gates made
it possible to control the flow of the
Shannon River and drop the level of
the water in Lough Allen.
These gates were built to
control the amount of water
flowing through Ardnacrusha
hydroelectric power station
in County Clare. They are also
used to control the flooding
along the Shannon River.
When the level of the lake
was lowered it was discovered
that the western shoreline of
the lake was once littered
with great oak trees. Oak does not grow with its roots in the water so
the lake was much lower then.