archaeological & built heritage assessment - The Heritage Council

6 Character Assessment Areas
For purposes of this study the area of the waterways corridor extending from Lough Allen to Roosky,
including the Boyle navigation and Carnadoe Waters has been subdivided into five geographical units in
order to comprehensively assess cultural heritage aspects pertaining to each area.
Area 1
Area 1 has been defined as that which includes the villages of Dowra and Drumkeeran, Lough Allen, Arigna and
Drumshanbo (Acres Lake, Drumshanbo lock Cavan & Letrim railway).
The Shannon Pot, where the river Shannon originates, is thought to be located in the foothills of the
Cuilcagh mountains, although it is likely that the real source is higher up in the mountain slopes. From
here, the Shannon continues southwards and is joined by another stream, widening into a small lake
before it meets the large Owenmore river. At this point, fed by numerous small streams, it becomes quite
a substantial river before it reaches Dowra. Here it is joined by another sizeable river, the Owennoyre,
before it enters the northeast corner of Lough Allen. For most of its course, the Shannon meanders
through the country broadening out into large lakes as it goes; a natural navigation with only an occasional
place where rapids occur (Delaney 1987).
At the southern portion of Lough Allen a canal opens from a small bay, continuing through Drumshanbo
lock and onwards to Acres Lake. Much of Acres Lake is surrounded by grassland subjected to fluctuating
water levels. The Lough Allen Canal was constructed in 1819-20 to enable coal mined in the Arigna area
to be carried down via the Shannon navigation to the Royal Canal, which had just been completed, in
order to transport to Dublin. However, the anticipated coal trade did not materialise and the completion
of a railway with a tramway extension to the mining area further diminished trade. When the hydroelectric
works were carried out in the 1920s, traffic on the canal had virtually ceased and so it was
decided to use Lough Allen as a reservoir with sluices to control it at Bellantra (Delaney 2000). This
resulted in great fluctuations in levels making it impossible to continue using the canal; the last boat passed
through in 1932. The canal was re-opened to Acres Lake in 1978 but could not be extended into Lough
Allen because of these fluctuations. Power from the Shannon scheme now forms a very small part of the
national grid and so the Electricity Supply Board agreed to keep Lough Allen at a more constant level and
the canal was re-opened into Lough Allen in 1996. Since the level of the lake varies, a two way lock was
constructed where the canal joins the lake.
Lough Allen is c. 11km long and almost 8km broad at its widest point, narrowing at its southern end. A
deep lake, it is almost completely surrounded by high mountains; the shore line is very regular with very
few bays and few islands. The dropping of water levels at Lough Allen has uncovered some interesting
areas where crannógs had been sited off the east shore and as well as other indications of early habitation.
At the north end of the lake there is a prehistoric ditch, known as the Black Pig’s Race, extending from
the village of Dowra towards the lake, which is thought to be part of an early man-made frontier which
defended the kingdom of Ulster. There are also number of early church ruins, including one on the island
of Inismagrath (LE018-037---) and two others along the west shore, at Conagh (RMP LE020-01001-) and
Tarmon (RMP LE020-003(01-02---), indications of the importance of the lake in ancient times. In terms of
archaeology, Area 1 is covered by RMP map sheets Leitrim: 18, 20 and 23 (see Appendix 1). Inclusive of
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