Fernilee is the first and older of the two reservoirs, constructed in 1938. On the east side of is a section of the old Cromford and High Peak railway line that once linked the High Peak canal at Whaley Bridge with the River Derwent in Cromford; the cradle of the industrial revolution. Although it was once a vital link in a chain of production, it is now one of the most scenic and serene walks in the Peak District. This section of the line closed in 1896.
Beneath the water are the remains of the Chilworth Gunpowder Factory which supplied chemical explosives from the 16th century until World War 1. Three men were injured in an explosion in 1909 and died of their injuries afterwards in Buxton Hospital.
The railway line included two sections where trucks were hauled up steep inclines by static engines. The first of these is the section of road which leads up from Errwood dam towards the Buxton road. You can see a smaller reservoir at the top, built to provide a water supply for the engine.