roof of the culvert collapsed into the river in January 2017. Major engineering work took place at Endcliffe Park in 2004-5, to reduce the impact of overflows from the sewage system under storm conditions, and to reduce the likelihood of flooding on the lower river. In September 2014 Sheffield City Council announced plans for a flood alleviation scheme on the Porter Brook and its tributary the Mayfield Brook. It was planned to create floodwater storage areas at Mayfield, Whiteley Woods and Endcliffe Park while parts of the watercourse would be contained by walled defences downstream of Endcliffe Park. The work on the Porter Brook and the Sheaf was costed at £12.4 million, and was part of a larger project costing £56 million. Work started in 2015, and was expected to be completed in 2021. Water power The Porter Brook, like the other rivers in Sheffield, is ideally suited for providing water power, as the final section falls some in a little over . This enabled dams to be constructed reasonably close together, without the outflow from one mill being restricted by the next downstream dam. In addition to this water-power, natural sandstone was available in abundance in the nearby hills of Sheffield and the Peak District National Park. Lying at the edge of these hills, mill-owners found Millstone Grit was an easily extractable resource. By 1740 Sheffield became the most extensive user of water-power in Britain and probably in Europe. Ninety mills had been built, two-thirds of them for grinding. By 1850 these mills numbered well over 100. In the Porter valley alone 21 mill dams served 19 water-wheels, mostly used for grinding corn, operating forge-hammers, and rolling mills, grinding knives and the various types of blade that made Sheffield famous. Most were active during the 18th and 19th centuries. Fulwood Cornmill A mill is known to have existed at Fulwood in 1641, when Ulysses Fox its builder appeared before the Court of Kings Bench changed with "trespass", as the rights to grind corn were owned by the manor. Despite having to pay £35 8s 9d (£35.43) the mill survived. Later, there were two wheels served by two dams lying between Mill Lane and Mark Lane in Mayfield Valley above Forge Dam. In 1760 the mill was used by Thomas Boulsover for the production of Sheffield-plate buttons. A steam engine was used at the Nether or lower mill from 1847,