of the Peak District's Dark Peak area. It is the lowest and largest of three reservoirs in the Greenfield Valley. Above it are the Yeoman Hey, built in 1880, and Greenfield Reservoirs. Chew Reservoir is in the upper Chew Valley and at 1,600 feet (488 metres) above sea level was the highest reservoir in the British Isles when it was built in 1914. The reservoirs are surrounded by moorland and, above the valley, high rocky outcrops. The A635 road to Holmfirth passes to the west and north of the reservoirs. Dam The Ashton under Lyne, Stalybridge & Dukinfield Joint Committee obtained an Act of Parliament in 1958 enabling it to build the reservoir. The committee engaged G.H. Hill & Sons as engineers and the contractor was A. E. Farr & Company. J.B. Blayney was employed as landscape architect as required by the Act. Work started in 1960 and was finished in October 1966. The dam's earth embankment is 38 metres high and 550 metres in length. It is 4.25 metres wide at the crest and is 183 metres at the widest point at its base. A concrete cutoff in a 23 metre deep trench makes a seal between the foundations and the earthworks preventing leaks. Above the concrete cutoff is the clay core. Dovestone is possibly the last large dam to be built in Britain with a conventional puddle clay core. The volume of the dam is 34,000 cubic metres. The dam wall does not have a traditional spillway to control water height but discharges into a tunnel under the side of the valley, via a large bell-mouth drop-shaft overflow in one corner, a feature not normally seen on Pennine dams ⁬which usually have masonry spillways. On the dam wall near the drop shaft is an ingeniously designed emergency overflow consisting of three metal troughs that when full tip water over a wall where it runs across the road and back into the river below. The emergency overflow is activated if a flash flood of approximately two metres of water occurs. Recreation Access to the reservoir is via the A635 road to the pay and display car parks. There are toilets at Binn Green and at the main car park. The Peak District Park Ranger Service maintains an office next to the main car park and rangers patrol the reservoirs and park at weekends. The reservoirs and surrounding moorland attract