On Sunday I walked from my house up to this reservoir. It was cold and clear. I could see snow covered mountains in the Lake District from the dam. It's capacity has recently been increased by the addition of the small wall on top of the earthen dam. It's the biggest bitumen surfaced dam in existence I think.
It's purpose is threefold - to provide instant power for the breaks in the FA cup matches when all football fans rush out into the kitchen to put the kettle on and to keep mains clocks running accurately (frequency control). It also keeps nuclear power stations running optimally by using their energy at night to pump the water back up to this reservoir, but it uses 4 units of electricity to do this and can only generate 3 units on the return.
The statistics are mindboggling - it goes from zero to full power in a few seconds and at that rate 82,000 gallons (372772 litres) a second travel through the six turbines.
I worked on this construction project for nearly three years. The mountain on the left is Carnedd Y Filiast (the greyhound rock is a rough translation).
Enough rambling... hope it cheers you up 'cos the weather is going to be rubbish this weekend
Taken with my little Fuji jpeg camera 'cos the beasty was too heavy to lug this far
 forgot to mention it's a stitch of six or seven frames in Photoshop, handheld.