The Vyrnwy dam is 146 feet high from the bottom of the valley, and 120 feet thick at the base; it is 1,165 feet long and has a public road running along the top. It is decorated with over 25 arches and two small towers each with four corner turrets rising 14 feet above the road surface.

The road across the top of the dam is wide enough for only one vehicle but because the road is straight it is easy to see if another vehicle is approaching before starting across.

Compensation water being released quite spectacularly. When the dam was built it would have reduced the river flow downstream significantly and would have affected people downstream who rely on the river water so water is deliberately released to compensate for that.

The straining Tower seen through one of the dam's arches. The water flows through these arches when the lake becomes over full and makes quite an impressive sight but, unfortunately, not this time.