The reservoir dam was constructed using stone quarried directly from the surrounding Mourne Mountains.
Engineers employed a 'cut-off trench' to reach solid rock foundation, reaching depths of up to 120 feet below the valley floor.
The reservoir holds approximately 3,000 million gallons of water when at full capacity.
Construction work involved over 1,000 men living in a purpose-built village on-site during the ten-year project.
The Silent Valley wall is part of the 22-mile long Mourne Wall, which was built to enclose the catchment area.
Silent Valley Mountain Park serves as the primary water collection point for Belfast and much of County Down. The park is defined by the massive Silent Valley Reservoir, constructed between 1923 and 1933 to address the region's increasing water demands. It is enclosed within the Mourne Mountains, providing access to diverse hiking trails ranging from gentle valley walks to challenging ascents. The site features an ornamental garden, a mountain sculpture, and educational displays detailing the history of the reservoir's construction. Visitors are restricted from swimming or boating in the reservoir to protect the water quality. The park is operated by NI Water and serves as a vital environmental and historical landmark.
The top of the main dam wall looking north toward the peaks of Slieve Binnian and Slievenaglogh.
Wear sturdy, waterproof hiking boots if you plan to move beyond the paved reservoir perimeter.
Check the weather forecast for the Mourne Mountains specifically, as conditions in the valley can differ significantly from surrounding coastal towns.
Bring layers, as the wind speed increases significantly at the dam face compared to the car park.
Do not attempt mountain hikes without adequate navigation tools, as phone signal is unreliable in the deeper valleys.
The park may experience restricted access or closures during severe winter weather or high-wind warnings.
Stick to marked paths to protect the water catchment area; dogs must be kept on a lead at all times.
