Early Derbyshire lead mines were fairly shallow, since methods to remove water were inefficient and miners had to stop when they reached the water table. The digging of soughs was found to be an effective way of lowering the water table and allowing mines to be worked deeper.
Soughs were typically dug from their open end near a stream or river back into the hillside beneath the mine to be drained. One sough would often drain more than one mine, since these were often very close, working the same vein of lead. This also helped spread the cost of digging the sough. Some soughs include branches to facilitate further drainage.
Many soughs were dug throughout the 17th and 18th centuries, until the falling price of lead brought the decline of the Derbyshire lead mining industry towards the end of the 19th century.
Some soughs were very extensive. Meerbrook sough is over four miles in length. Digging such long tunnels took a long time. Vermuyden sough, named after the Dutch engineer Sir Cornelius Vermuyden who planned it, took twenty years to dig. The Cromford sough that Sir Richard Arkwright subsequently used to power his mill at Cromford took thirty years to dig, and was still being extended a century after it was begun.
Some soughs are still in use. According to the British Geological Survey, the Meerbrook sough, started in 1772, still provides 3.75 million litres a day for the public water supply.