During excavations at Piethorne in the mid-19th century, a Celtic spear-head with a 5-inch (130 mm) blade was unearthed, implying human habitation in the locality during the Bronze Age.

During the excavations for the reservoir, a Celtic spear-head with a 5-inch (130 mm) blade was discovered, implying human habitation in the area during the Bronze Age.

Piethorne and the other reservoirs were built using an impermeable clay puddle core to seal the dams, supported by strong earth material.

Navvies trod the clay wearing boots with sacking tied around their legs until the full reservoir height was reached.

One Betty Whitehead, a seventy-year old local woman, recalled in the Oldham Chronicle newspaper in 1957 that the navvies "usually had a pocketful of money and a bellyful of beer".

The entire 736 hectare watershed, known as the Piethorne Valley, also hosts walking trails, angling, and provides opportunities for observing wildlife.