Dogleap Powerhouse, Roe Valley Country Park, 43 Dogleap Road, Largy, Limavady, Co Londonderry, BT49 9NN

Dogleap Powerhouse

A tall single-storey stone building with red brick trims around openings, located adjacent to Largy Bridge in Roe Valley Country Park. The building drops to two storeys on its north side facing the River Roe. It has a new corrugated metal roof and its south-west corner is curved, featuring a sandstone plaque beneath the overhanging eaves inscribed 'built by J T and his wife E J S Ritter 1896'.

The main south-facing facade is simply composed: a door opening, a window opening, and to the east a 2.5-metre-wide slot with shutter doors at ground level and painted matchboarding above. The east gable has brick quoins, a central window, and evidence of a former extension visible in vertical lines of brickwork incorporated into the northern quoins. The north side, overlooking the river where ground level falls steeply to a path below, contains two windows and a 3.5-metre slot with a large window serving the plant room. Horizontal matchboarding sits above this window, with the wall below built up in brick and further rendered. The west gable adjoining the bridge carriageway has no openings.

The building is important primarily for the surviving hydro-electric machinery inside and represents the only surviving example of such a structure in Northern Ireland. In 1893 John Ritter began experimenting with electricity generation to light his house at Roe Park, initially using a paraffin-oil engine and water wheel. In 1896 he erected this hydro-power station at Largy Green, equipped with three McAdam water turbines generating alternating current. The success of this venture led him to form the Limavady Electric Supply Company in 1897, which began supplying electricity to Limavady. In 1904 the McAdam turbines were replaced by a more efficient 90-horsepower turbine built by Escher Wyss of Switzerland. The closure of Limavady Gasworks in 1918 due to coal shortage boosted the company's fortunes, and in 1924 an additional 150-horsepower Hay-Manyon turbine came into service. From the 1930s to 1940s diesel generators were added, supplemented by another generator at Roe Mills (now demolished). By 1935 Limavady Junction and Ballykelly had been linked to the company's network. In 1946 the Electricity Board for Northern Ireland acquired the station. By the mid-1960s it was producing less than one per cent of Northern Ireland's electricity needs, and in 1967 the station closed. In 1976 the building became part of the newly established Roe Valley Country Park under Department of the Environment ownership. The building was listed as Grade B in 1975 and upgraded to Grade B+ in recognition of its significance as the only surviving hydro-electric power station in Northern Ireland. In 1994, following privatisation of the electricity service, Coolkeeragh Power Ltd investigated restarting commercial electricity generation, submitting a planning application proposing to reuse the western millrace from Moore's Weir, dredge the mill pond, and install a new generator. This scheme has not yet been developed.

The curved wall and its inscribed plaque, though likely resulting from practical considerations, enhance the picturesque quality of the setting. The building is listed as a Grade B+ heritage asset and is now used as a gallery and museum. The listing extends to the building and adjacent weir.