Monument record 10885 - Wier, Dee Mills (Salmon Leap)

<1> Bennett R & Elton J, 1898, History of Cornmilling, Vol.IV p.55-123 (Book). SCH1417.

Earl Hugh Lupus granted St Werburgh's Abbey a site for a mill at Dee Bridge in 1093 (Dee Mills). The stone weir or causeway was constructed at this time to obtain head of water sufficient to drive the waterwheels of the Dee Mills. The barrier across the river was often adversely criticised. Only because the weir/causeway had been constructed prior Edward I reign did it survive the enforcement of to an Act of 1352 which ordered the destruction of all causeways in navigable rivers erected after his reign. Commonly the cries for its destruction were founded on the fact that the weir/causeway blocked the navigation of the river. In 1601 Edmund Gamull and John Tyler, lessee of the mills and operator of the city waterworks respectively, to not supply water to those people who refused to grind at Dee Mills. In the same year the weir/causeway was damaged in suspicious circumstances. Claims were also made that Gamull has raised the height of the weir/causeway. In 1608 the Commissioners for Sewers at Denbigh found the causeway was a hindrance to navigation and the cause of floods. A second inquisition at Wrexham returned a similar verdict and a formal decree was made for a break 10 yards wide should be made through the causeway. An inquisition held by the Exchequer Court at Chester presented a verdict against the commissioners order being carried out. Those wishing the destruction of the causeway threatened '' to come very speedily to Chester with great multitudes to put the decree into execution ; so that the memorye of the antient enmitie and hostilitye between the English and the Welsh is revived". An appeal against the Commissioners was made to the Privy Council, who decided in 1609 that the Commissioners had no power to issue their decree. In 1646 the citizens of Chester and the mayor appealed to the Commonwealth for the abolition of the causeway and the mills. The parliamentary representatives ordered the destruction of the mills and causeway within four months. Although workmen were appointed for the task on the 6th December 1648, the order wasn't carried out (1). There were fish traps, associated with the weir, below the bridge.

<2> Harris, B.E., 1979, Bartholomew City Guides - Chester, p.149 (Book). SCH394.

There were fish traps, associated with the weir, below the bridge (1). The weir survived all changes to the mills and their demolition in 1910. It was tidied up by the City Authorities in the early twentieth century. It is covered by the highest tides.

<3> Ward, S. W., 2009, Chester: A History, p.46 (Book). SCH5305.

Possibly constructed in the twelfth century to supply water to the Dee Mills (CHER 10881), located at the end of Dee Bridge, which were constructed at the same time.

<4> Various, Aerial photographs, Chester 3 Williams S R 1977 (Aerial Photograph). SCH128.

<5> Hughes Sub Surface Engineering Ltd, 2015, Chester Tidal Weir Inspection Report (Client Report). SCH7968.

Hughes Sub Surface Engineering Ltd was commissioned by Cheshire West and Chester Council in July 2015 to undertake a diving and surface inspection on the Chester Weir located on the River Dee to check its overall condition, including any defects, scouring and undermining. The inspection occurred between 29th and 31st July 2015. A walkover survey was made to assess the general environment surrounding the weir in advance of the diving inspection. Additionally a walkover inspection was made to check the visible/shallow water elements of the upstream weir structure and crest.

The current weir was originally the site of a causeway across the River Dee (remenants of which exist immediately downstream of the current weir toe. The weir is believed to have been first constructed in sandstone in 1093.

The weir continues to provide three essential roles in maintaining the very substantial water abstractions from the River Dee. It prevents tidal water ingress up-river for all but the highest tides; it provides the water head for an abstraction immediately behind the weir and it holds back what is a long linear lake which enables the largest abstraction to be taken at Huntington for the United Utilities supply to the Wirral and surrounding area.

The weir structure was found to be in overall good condition with no obvious signs of gross defect. Its back face was intact although its profile varied along its length. The masonry blockwork setts were found to be intact, secure and well jointed. The upstream silt river bed meets the back face of the weir approximately 7m back from the weir crest. Some localised debris overlay the back face. The crest was found to be intact and functioning, with flow rates over its top regular and without any obvious interruption. The sloping weir appeared to be in good condition. Minor scour was observed along the length of the toe blocks to weir slope; the blocks were complete but had an irregular alignment. More significant scour was noted at CH10 at toe level and it is recommended that areas of scour should be monitored. Also recommended was survey by high resolution multi beam echo sounder at mean high water springs to produce a 3D digital image of the entire weir structure.