The River Darent powered a large number of watermills some going back to Domesday and many in operation until the early 20th century. There were mainly corn mills from the source up to Dartford. In the Dartord area there was reputedly England's first paper mill and also silk printing works,a gunpowder mill, a mustard mill and cotton mill all powered by the river. Dartford Powder Mills was the scene of a catastrophic series of explosions. At least twenty-seven people were killed in explosions at the Gunpowder Mills between 1750 and 1800. The river was increasingly used for trade during the 1800s and was straightened, widened and in some places given concrete banks to increase its usefulness. In 1835 approximately 50,000 to 60,000 tons per annum were being carried on the river. Conversion into a ship canal was once proposed but never came to anything.