- Our popular Spooky Dam Open Day is back! Walk through Penbont Woods and enter Pen y Garreg dam – if you dare! Tuesday 29th & Wednesday 30th October Book your 30-minute slot from 1pm to 3pm, on our website. https://elan-valley.co.uk/events/spooky-dam-open-day/ £5.00 per adult, £1.50 per Under-18 (half the proceeds go to WaterAid)