| Reconstruction & development
Left: A stone staircase by the side of the Shepherd Wheel, Porter Valley, Sheffield. In 2011, a masterplan for the Porter Valley identified 15 separate packages of work to be undertaken over a number of phases. The first was the Shepherd Wheel which was successfully completed by the Friends of Porter Valley in 2012. It now demonstrates traditional blade sharpening techniques powered by the restored water wheel and is an example of successful collaboration between FoPV, Sheffield Museums’ Trust and Sheffield City Council. After this success, the Friends of Porter Valley turned their attention to the next project in the masterplan – the restoration of Forge Dam
Above: Many visitors to Forge Dam come from the city of Sheffield
grow, however the heavily silted millpond detracts significantly from the visual amenity of the area.
Desilting Forge Dam millpond is unusual in that it is an on-line
structure impounding an area of the Porter Brook covering approximately 5760m2
, which is just below
the Reservoirs Act threshold. The dam consists of a large earth embankment across the Porter Brook Valley, approximately 45m in length, with a concrete wall along its upstream face. The Porter Brook discharges over a spillway at the southern end of the embankment, dropping about 6m to the stream below. As the first mill pond reached by the River Porter,
Forge Dam was not designed as an “off shot” but receives the full force of this very flashy river. It is the first place the River Porter slows down on its journey from its source in the hills above Sheffield. The on-line structure at Forge Dam has acted as a sediment trap for coarse and fine material since construction and regular desilting is no longer practised. Desilting activities have occurred throughout
the site’s history with the last major works being carried out in 1991. In Thomas Boulsover’s day these
silting problems were easily solved with manpower. However, in the 21st century with council budgets stretched to cover essential front-line services, Sheffield’s network of mill ponds has largely been left to naturalise. By 2021, Forge Dam had silted up to such an extent that it was on the point of being lost. During dry weather, silt was visible above the water line and the ducks were walking not swimming.
Friends of the Porter Valley Friends of the Porter Valley (FoPV) is a volunteer
organisation established in 1994 to conserve, protect and restore the ecology, landscape and cultural heritage of the valley for the enjoyment and benefit of future generations. They have been a major driving force behind the restoration of Forge Dam. Back in 2010 Sheffield Council was made aware of the poor state of Forge Dam through a public petition. One year later it engaged consultants to produce recommendations for restoring the structure. Although two previous attempts had been made in the 1970s and ‘80s to desilt the dam, with the latter project creating the current island in the mill pond and the installation of a silt trap just upstream from f
Bottom left: Educational walking talks have been organised at Forge Dam, led by David Young, one of FoPV’s longest serving committee members and a water engineer by profession
Below: Electrofishing to remove fish before draining the dam. The large fish were moved upstream and the smaller ones down. Nets have been strung across the river upstream to prevent them getting back during the work
www.waterpowermagazine.com | March 2022 | 19
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