Estuary of the River Mersey : The effect of the discharge of crude sewage into the estuary of the River Mersey on the amount and hardness of the deposit in the estuary.

  • Great Britain. Water Pollution Research Board
Date:
1938
Catalogue details

Licence: Public Domain Mark

Credit: Estuary of the River Mersey : The effect of the discharge of crude sewage into the estuary of the River Mersey on the amount and hardness of the deposit in the estuary. Source: Wellcome Collection.

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    Ship Canal during a period of four hours on either side of high water. In the upper basin itself there are no channels of navigable depth at low water but at high water a large carrying trade is done by small steamers and barges, some of which are bound for Widnes while others lock into the Manchester Ship Canal. At high water also, small vessels use the channel between Widnes and Warrington, the upper part of which is dredged. Considerable volumes of sewage and trade wastes are discharged into the Estuary. Almost the whole of the sewage from the towns on the Estuary banks is discharged in an untreated condition and the sewers carry also most of the trade wastes of the district. The industries on Merseyside are varied in character. They include groups of industries which give rise to polluting effluents; of these one of the most important is tanning. Many of the fresh-water streams flowing into the Estuary pass through thickly populated industrial areas and are heavily polluted when they enter the Estuary. While little information is available on the changes which have occurred in recent times in the volume and character of industrial effluents discharged, there is no doubt that, with the growth of population and changes in sanitation, the volume of sewage entering the Estuary has increased within recent years. Since the year 1858 the Navigation Authority for the Estuary has been the Mersey Docks and Harbour Board. The upkeep of buoys in the upper part of the Upper Estuary and certain other duties, however, are carried out by the Upper Mersey Navigation Commission, while certain other work in the Estuary is done by other authorities, for example, by the Manchester Ship Canal Company and the London Midland and Scottish Railway Company. The Mersey Docks and Harbour Board surveyed: the Upper Estuary and measured its capacity in 1861, 1871 and 1881, and since that time they have made surveys at five-yearly intervals. They also carry out the dredging in Liverpool Bay and survey and mark the navigable channels and banks in this area. In recent years Parliamentary Bills, which might result in the discharge of additional sewage into the Estuary, have been opposed on the ground that the discharge of crude sewage makes it more difficult to keep open the navigable channels. The opinion has been expressed that the discharge of crude sewage causes deposition of mud in the Upper Estuary and changes the nature of the deposits in such a way that they are less easily eroded by the tidal streams. It was accordingly said that discharge of crude sewage led to a decrease in the tidal capacity of the Upper Estuary and thus reduced the quantity of water available for scouring the sea channels on the ebb tide, and that this decrease in the scour in the sea channels resulted in increased deposition in them, thus increasing the amount of dredging necessary to maintain a navigable depth. The presence of sewage was also believed to have led to the deposition in the sea channels of muddy material which is difficult to dredge. The Mersey Docks and Harbour Board have held that in order to keep open the sea channels in Liverpool Bay the tidal capacity of the Upper Estuary must be maintained and for this reason the building of the Manchester Ship Canal was opposed by them in the years 1885 to 1888 on the. grounds that the construction of the Canal, especially in the form first proposed, would lead to the silting up o the upper basin. 5