The Medlock was one of three important rivers passing through the centre of Manchester, the largest being the River Irwell (which was joined in the city centre by the River Irk and the Medlock. There were several minor rivers or streams, including the River Tib and Shooter's Brook. More waterways were added in the 18th and 19th centuries, principally the Bridgewater Canal, Ashton Canal, and the Rochdale Canal.
These waterways supported a vast number and variety of factories. Early maps show isolated mills, dye works, etc., by the rivers, which used water to power the machinery. Steam engines took over, and they needed water for feeding the boilers and condensing the steam. Other factories needed water for various production processes involving bleaching, dyeing, chemical manufacture etc.
These rivers shaped Manchester, their sinuous routes defining both the location and the form of the many factories which lined their banks. These encroachments of buildings largely hid the smaller rivers from view, and today only odd glimpses can be seen within the city.
The River Medlock is a small river, and its flowrate was very variable.
It was stated in 1868 that the flow was just 7000 gallons per minute in dry weather. However, flooding was not infrequent, and in an extreme case in 1856, it was determined that the flow rate increased to 2400 cu ft per second. This is approximately 900,000 gpm.
While the quantity varied, the quality only became progressively worse, and eventually intolerable. The river was used and abused by all and sundry, being convenient for disposing of sewage, factory effluent, ash and cinders and various other solids. Its nadir probably came with the introduction of small gas lighting plants in factories, whose tar and ammonical liquor were unwanted by-products, dumped into the nearest waterway.
Long before pollution became a problem, James Brindley had linked the Bridgewater Canal with the River Medlock at Castlefield. The required level at the junction was maintained by a weir constructed at Castlefield. This was of 'cloverleaf' shape in plan. The six 'leaves' gave the crest a large peripheral length for a given diameter. Once over the weir, the water passed down a circular pit, and then through a short tunnel to rejoin its old course (see photo), joining the Medlock to enter the River Irwell.
It seems inevitable that introducing a weir would result in the upstream river bed becoming, to some extent, a settling chamber for the solid material carried by the river. Certainly problems did arise with silting of all Manchester’s rivers, leading to serious flooding.
The 1848 O.S. map shows that Brindley's scheme had been altered at Castlefield. The cloverleaf shape had gone, replaced by a circular feature marked 'Giant's Basin', draining through a short tunnel to the rejoin the old course of the River Medlock. A dam with a sluice had been introduced at nearby Knott Mill Bridge, and immediately upstream of this is an overflow. Evidently the flow of the river was diverted through this overflow, into a fairly narrow tunnel, shown clearly on the map heading north-westwards. This emerges alongside the short tunnel from the Giants Basin (see photo), from where the river regains its old course. The upstream part of the tunnel does not appear to be generously-sized, and no doubt the limited change in elevation over its length - together with the need to burrow under Castlefield Basin and the Rochdale Canal - limited the scope for providing the optimum gradient. Adshead's 1851 Map shows a series of circular features at various places along the line of the tunnel. marked 'Grid'. These grids were presumably at the top of shafts. It has not been established whether these shafts were there for construction or maintenance purposes, or whether they were required to prevent air locks in the presence of unfavourable gradients, or simply for surface drainage. It appears that this tunnel was being dug in 1830 by workmen of the Trustees of the Duke of Bridgewater:-
1830 'New Tunnel at Knott Mill.— We understand that workmen employed by the trustees of the Duke of Bridgewater's canal, are now engaged in the construction of a tunnel, leading from the Medlock above that part at which it joins the canal, for the purpose of carrying off the superfluous waters of that river, the whole which have hitherto flowed into the canal. The tunnel after leaving the Knott Mill, will pass under Castlefield, and under the branch of the canal near the Staffordshire warehouses, and will then discharge itself into the old channel of the Medlock, in Hulme fields, a short way above the point of junction with the Irwell. The construction of this tunnel has been found necessary, in consequence of the canal being nearly filled with mud and dirt from the impurity of the water of the Medlock, a very small proportion of which only is required for the supply the canal.'
Evidently problems had been experienced with the cloverleaf weir, which may partly explain the changes, but a compelling need for alteration stemmed from severe pollution of the Medlock. The new tunnel diverted the Medlock away from the Bridgewater Canal basin, and a new supply of good water was obtained directly from the Rochdale Canal, which joined the basin at Lock 92. Presumably at times of heavy rainfall, polluted water from the Medlock could enter the basin by overflowing the Knott Mill weir. Excess water could escape via the 'Giant's Basin'. At some point (1880s?) the overflow at Knott Mill was altered to a 'tilting weir', which can be seen in old photographs  . Some or all of the mechanism is still present (see photo on this page).
This interpretation of the alterations seems to be supported by the following 1833 and 1849 newspaper reports:-
'EFFECTS OF THE LATE STORM ..... The streets in many parts of the town (says the Manchester Courier) became towards night almost impassable, & many of the sewers & drains were choked up. The river Medlock rose to a greater height than it had been known to do for the last thirty years, and much damage was consequently sustained by the numerous works carried on upon that river. Mr. Green, dyer, Garrett, had his premises considerably flooded ; the water entered his drysaltery store-room, and damaged goods to the amount of about four hundred pounds ; it also carried away part of one of his buildings. A little lower down it entered the factory of Mr. Paul Chappe, and completely inundated one of the lower rooms, filled with valuable machinery. A quantity of cotton was also much damaged. Much of the mischief is attributed to an obstruction in the river, caused by the works recently erected at Knott mill-bridge, by the Trustees of the late Duke of Bridgewater, for conveying off the river by a subterraneous passage to the Irwell, which caused the water to rise higher than it would have done if there had been no such impediment. This opinion is strengthened by the fact, that higher up the river, beyond the influence of the obstruction, the water did not rise higher than is usually the case in great floods, consequently comparatively little damage was sustained in those situations. The river Irwell soon became filled, and from its sudden rise considerable damage to property on its banks was anticipated, but we understand that no further injury was done than the forcing down part of an embankment about thirty yards in length, and the overflowing of several meadows on the line. .....'
'Contemplated Improvements of the Bridgewater Canal.—
When the Bridgewater Canal was first constructed,all the water courses running through Manchester were filled with comparatively pure water, and Mr. Brindley, the celebrated engineer to the Duke of Bridgewater, who was originally a millwright, made water-wheels at the warehouses first erected, for the purpose of hoisting goods from the boats into the warehouse rooms. Such warehouses as have been erected since have also had water-wheels added to them.
We need scarcely observe that the traffic of the canal has gone on steadily increasing since the period of its establishment, far back, if we mistake not, as 1769, up to the present date. The growth of Manchester since the construction of the canal has been almost unparalleled, and the water-courses, which at that time were comparatively pure, having the refuse of dye and print works, and the drainage of the whole districts densely populated, turned into them, have now become highly vitiated, and in fact tainted to a dangerous extent. The water thus vitiated is still admitted into the canal, and many of the water-wheels at the warehouses are occasionally worked for the purposes for which they were erected.
The consequence is that a great body of water is required from the Medlock, which, being a great degree stagnant, emits a most offensive smell.— The water-wheels exist at Prestonbrook, Worsley, and other intermediate stations, besides at Castlefield, in Manchester, and the vitiated water is drawn towards the farther districts, the flow being in that direction, and consequently the offensive effluvium from the canal is experienced for very many miles along its banks. The fact of the water wheels being the only power except horse or manual labour used for hoisting to the warehouses, has also had tendency to cause the wheels to be more worked and more water to be used than could well be spared from the canal.
Every portion of the vitiated water of the Medlock was, till recently, admitted into the canal, to replace in some measure that drawn away by evaporation, leakage, and the working of the wheels. The trustees of the canal some years ago directed their then engineer, Mr. Rawlinson (now superintending inspector of the general board of health), to examine the whole subject of the supply of water to the canal, and to report to them as to the best means of preserving the purity of the canal and dispensing with the water of the Medlock. Mr. Rawlinson, after careful examination, in his report recommended that every water wheel should be superseded, substituting, where necessary, a steam engine, for the purpose of hoisting the goods from the boats into the warehouses. With that view one engine was shortly afterwards put down at Castlefield, and it was fully intended gradually to have superseded, at least at Manchester, the other mode.
A few years since, the trustees of the canal, foreseeing that the Medlock water must be turned out of the canal, constructed (at very great expense) a tunnel under Castlefield down into the River Irwell, and which tunnel is capable of taking the whole of the waters from that river. It was also in contemplation at that period to arrange with the Rochdale Canal Company to pass down their canal a larger quantity of pure water to supply any deficiency that might be experienced in the Bridgewater Canal when the Medlock water was no longer used. Mr Loch, one of the trustees, also proposed to erect a steam-engine at Stretford, for the purpose of pumping water from the Mersey into the canal, but whether that could be done without interfering with the existing right to the water possessed by other persons, we are not aware. However that may be, the scheme has hitherto been in abeyance. But it is quite possible that if the trustees avail themselves of the means within their power they may restore the canal to its primitive purity. The Bridgewater Canal has a valuable peculiarity, in the fact that every canal with which it joins locks into it. We have heard that it is in contemplation speedily to effect the necessary improvements, and we feel assured that the Earl of Ellesmere will incur any reasonable expenditure that may be necessary to promote the health and welfare of the community at large.' 
1857 Summer Floods
Effects of flooding on houses and industrial premises and goods described in some detail in newspaper reports. . Extract:-
'The principal damage, however, done by the flood, has been caused, as was the case this time last year, by the overflowing of the Medlock, on the banks of which are situated some of our largest cotton manufactories. To these mills in the aggregate we believe that damage to the amount of between £30,000 and £40,000 has been done, and what is perhaps worse a great number of factory operatives will most probably be thrown out of employ for some time. The mill of Messrs. J. and W. Bellhouse alone, in Garratt-road, has again suffered damage to the extent, it is believed, of £6,000. About this time last year it will be remembered, that the mill of Messrs. Bellhouse was flooded by the overflowing of the Medlock, and that they subsequently recovered £4,500 damages from the corporation of Manchester. After the last flood Messrs. Bellhouse did all in their power to protect their property for the future, and had a boundary wall built adjoining the river of between three and four feet high. Last night, however, the river is said to have been flooded three feet six inches higher than last year, and the consequence has been that this boundary wall has been washed down and entirely demolished ; their boiler-house in the yard has also been washed down and unroofed, and the water entered the carding room situate on the first floor of the new and old mill to a depth of six or seven feet. The machinery, when we saw it Saturday morning last, appeared to have been much knocked about, bobbins were strewed in all directions, and the rooms were a complete wreck. As we have stated, the damage done to the machinery and buildings of this mill is of very serious nature, and we regret to have to add, that in consequence of the flooding of the carding rooms, the production of the mill will be stopped for some months. Messrs. Bellhouse complain, perhaps with great justice, that although it is now twelve months ago since the last flood which did damage to their mill, the corporation have taken no steps to remedy the evils resulting from the bridge thrown across the river, and for the misconstruction of which they obtained their verdict against them.
At Ancoats Bridge, the damage done to the mill of Messrs. Marsland is also of a very serious nature. About one o'clock this morning the watchman on duty at the mill heard a terrible rush of water, and on making an examination found that the card room was flooded to the depth of about 9 feet. The water also spread to the place where the watchman was standing, and it was with some difficulty that he made his escape having been first immersed to the middle.
Part of shed belonging to the Hanover Mill Co., at Buxton-street, London-road, also on the banks of the Medlock, has been washed down, and the water has entered the mill in lower storey, and no doubt caused damage to the extent of some thousands of pounds. The public baths and washhouses, situated on the opposite side of the river, have been flooded, and at Ardwick-bridge, London-road, the water covered the highway for a distance of about 200 yards, and consequently flooded the cellars of the different shopkeepers and other places of business. The Royal Oak Inn, one side of which abuts the river, has been very seriously flooded, the cellars and lower rooms having been filled with water, and it was only about nine o'clock this morning that the inmates were able to descend from the higher to the lower storeys. The Yorkshire House, Pin Mill Brow, Ancoats, kept by Mr. Robinson, was flooded, and the barrels of ale in the cellar were floated, and their contents somewhat damaged. A quantity of spirits was lost. The water was 7ft. 6in. deep in the cellar.
The Bridge Inn, Ancoats, close to the river Medlock, has also suffered much by the flood, three brews of ale in a state of fermentation having baen spoiled. The house is kept by Mr. Stone, and attached to it there are stables, in which were two horses. Mr. Stone, jun., with considerable difficulty rescued one of the horses from the stables, but the other having his head fastened to the manger, could not be rescued, the animal was drowned. Amongst other sufferers in this locality were Mr. David Mossley, of ths Chapelfield India-rubber &c Works, near Tipping-street ; Mr. Crabtree, dyer, Lime-kiln Lane, Messrs. C. Ramsey, of theBank Vale Dyeworks; Messrs. F. Hilton and Co., of the Holt Town Mills; and Mr. William Jones, cotton spinner, Mount-street.
Messrs. Cunliffe & Sons, tanners, &c., Nether-street, Tipping-street, have suffered perhaps more from inconvenience than actual damage, although the latter will be considerable. In what is known as their upper warehouse there was leather worth £5,000 or £6,000 : and the lower warehouse being filled, there was 2ft. of water in the upper one. A quantity of bark was wetted; but the water fortunately subsided before it reached the tan-pits, as otherwise the loss would have been very heavy. The damage will not be really known until the wetted goods come to be worked upon. The premises of Messrs. W. Andrew and Co., dressers, dyers, and finishers, Tipping-street, were left in a pitiable condition. At one point, when the flood was at its height, there was 14ft. of water; and some of the drying cylinders in one of the stove rooms were lifted out of their sockets. In another part we saw bags of shumac piled to height of 7ft. 6in. saturated, with the exception of about 6in. of the upper bags; the shumac was said to have been worth £300. Until August last, no flood-water had got into this part of the works; and on Saturday morning it stood 4ft. higher than upon that occasion. The fustic bins, indigo vats, &c, indeed nearly all the ground floor portions of the works, were left nearly lft. deep in mud ; and things were upset and smashed in most strange manner.
At Ardwick Bridge the stream rushed across tho London-road, which was flooded several feet deep ; the water of course extending over the hollow at that point, and getting into the premises of shopkeepers and others who were not exposed to danger directly from the river. Amongst the sufferers at this point were the following:— Mr. Simister, wholesale confectioner, &c. The cellar was completely filled and goods removed thence to a shelf in the shop were injured, as the water rose there to height of 18in. Mr. Arnold, grocer, had rather an extensive stock in the cellars, all of which was thoroughly saturated or spoiled, and the water covered the shop floor to depth of more than two feet. Mr. Gaskin, grocer, suffered severely ; as did also Mr. James Thompson, manufacturer; and the Bridge Inn, addition to other damages, a horse was drowned. Two unoccupied houses belonging to Mr. Rogers, on "Ardwick Island," were washed away.
At the extensive works of Messrs. Wren, Wren, and Hopkinson, engineers and millwrights, Temple-street (which stand almost on an island, owing to the tortuous course of the river), the foundry on one side of the street, and the timber yard on the other, were flooded. The water was 14in. over the foundry floor; and, taking the cellars, there was 11ft, of water to be got rid of. A good deal of timber was washed out of the yard ; but it is believed that a few hundred pounds will cover the loss of the firm, as the chief cost will be in getting out the water and polishing up the rusted ironwork. We were shown some marks in one of the boiler-houses, which we give as another indication of the extreme height of the flood ; the marks showing the depth of water actually lodged in the premises at the times mentioned : The flood of August last rose 20in. above the mark of " Holmfirth ;" but on Saturday morning there was excess of 17in. over the period first named.
The New Garrett of the late Mr. Samuel Green ; and different portions of the building are occupied by Mr. J. Donaldson, oil-cloth manufacturer ; Mr. J. Henry, manufacturer ; Mr. S. Pitt, building material broker; Mr. T. Chadwick, glass manufacturer; and Messrs. Mills and Co., railway grease manufacturers. It is the lowest piece of ground in the township, and as soon as the river began to swell the water rushed over it with great impetuosity. The first building which it encountered was an occupied indigo dyehouse, a portion of which, situated just at the bend of the river, was washed completely away, the boundary wall falling into the stream. A clear course was thus afforded for the current in this direction, but the water which had by this time covered the yard and entered the ground floors of the whole of the building at first found no outlet. It rapidly rose in height, amd penetrated into some of the second floors ; but still it was bayed back, the buildings covering the whole of the upper bank of the river. At length the current increased in velocity, and two of the weakest portions of the buildings were washed in, thereby giving an outlet for the water into the river. Some idea of the immense force of the water may be formed when we state that an enormous stone tank, weighing upwards of ten tons was torn from the place where it been fixed and carried forward several yards. The indigo dyehouse was covered to the depth of eight or ten feet, and addition to the outward wall being carried away, several, of the internal brick partitions were carried off. The whole of the premises were inundated; but fortunately there was not much property to be injured. Mr. Donaldson's stock of oils and chemicals was damaged, several casks of oil having burst; and Mr. Pitt had a quantity of building materials washed away. The water entered Messrs. J. and E. Westhead's smallware mill, Brook-street, and a quantity of cotton was injured. At Messrs. Edmondsons engraving works, in Charles-street, the engine-house was flooded to the depth of seven feet, the boiler fires being consequently extinguished. At the Old Garratt dyeworks (Messrs. William Douglas and Co.'s), a large amount of property was destroyed.
We may add in addition to what we have stated as to the damage the overflowing of the Medlcck, that Messrs. Birley's mill, Oxford-road ; Messrs. Gansey's, Buxton-street; Messrs. Hoyle's print works, Buxton-street; Alderman Barnes' mill, Jackson-street, and others situated on the banks of the same stream have all received damage to a greater or less extent, and most probably the sum which we have stated, as the amount of the damage done, is rather under than over the mark. Although, so far as we have been able to ascertain, only one life has been lost, the results might have been far more serious and fatal when it is considered that the pesthouse or Augean stable of Manchester, Little Ireland, was so completely flooded by the overflowing of the river Medlock, that many of the houses were filled with water to the ceilings, and the inhabitants had to make their escape through the roofs, or as best they could, assisted by the police. Of course, tbe alarm which prevailed was very great, and many narrow escapes took place ; and in the neighbourhood of Ancoats along the banks of the Medlock, the police thought the inhabitants of some cottages in such imminent danger, that in the middle of the night they warned them to leave their houses, and in many instances their furniture was removed to places of safety. .... In conclusion we may state that these floods, although periodical occurrences, are not without their compensating advantages to the city, for whilst on the one hand much damage is usually done to the mill property, which has unfortunately been built on the banks of our three streams, on the other it must be remembered that much of the salubrity of Manchester depends upon the thorough cleansing which these floods give to the sewers and drains, and these same polluted streams, misnamed '"rivers," the Irwell, the Irk, and the Medlock ; and there can be little doubt that were it not for these floods and the great falls of rain for which Manchester is celebrated, that we should not be able to boast that the mortality of the city is something like eleven per cent, less than that of the neighbouring town of Liverpool. ...'
Action was taken by the Manchester Corporation in the 1860s to address the flooding problem. They obtained an act to outlaw the dumping of rubbish in the river, and embarked on a programme of improvements, which included building walls and excavating 60,000 tons of deposits. The engineer in charge was J. F. Bateman. The progress was described by Mr Bateman in The Engineer in 1868. An ingenious arrangement was used to allow the work to be done without diverting the river. Sections about 200 yards long were worked on, dams being constructed at each end. Water was carried over or through the area of excavation by a wooden conduit of rectangular construction (see engravings). Spoil was shovelled into small wagons, and these were lifted by an Appleby Brothers steam crane and tipped directly into carts for disposal.
In addition to the problems at and near Castlefield basins, the encroachment of buildings and the construction of bridges and buildings resulted in serious flooding. The alterations in the 1860s did not eliminate flooding. Part of the problem was due to the presence of a number of weirs (see below). Some of these were built by mill owners, and at least part of the reason was to provide a reservoir of water which they could use for their steam engines' condensers in times of low flow in the river. In the 1880s tilting weirs, to the patent of Francis Wiswall and William Henry Collier, were installed, replacing the original fixed stone weirs. These were intended to allow the weirs' owners to continue impounding water in normal conditions, while responding to flood conditions by automatically tilting to reduce the weir height. They could also be manually controlled using a hand-operated crab (winch) fixed above river level. There was some controversy about whether they would work, aired in correspondence between William T. Olive and Francis Wiswall in 'The Engineer'.
'THE RIVER MEDLOCK IMPROVEMENT SCHEME. ....the disastrous flood which occurred two years ago. It would be in their remembrance that that flood was of unparalleled magnitude; many places of business were completely submerged, many dwelling houses were flooded, and great distress was caused; many large owners of property suffered severely, some to the extent of £10,000, and many of their poorer citizens suffered grievously. It had been stated that that was extraordinary flood, and, whilst they fully admitted that, it must be acknowledged that what had happened once might happen again. The condition of the river as it passed through Manchester, and for miles around, had so far changed that it was probable that floods in the future would increased in volume.
'The 1862 committee was formed to take into consideration what steps should be taken with regard to this question, and they recommended the clearing of the river of such obstructions were supposed to be the cause of the floods, but the scheme then adopted had not accomplished its object. The present committee had gone into the matter very carefully. Their first feeling had been that best plan would be to restore the river its original position, and to do that they would have had not only to get rid of the bridges and viaducts but also the weirs, and more especially to prepare new outlet. When they came look at such a scheme they found so many difficulties to prevent its adoption that they were bound give it up. It might be urged that those who put the weirs on the river might be compelled to take them away, but where these water privileges had been allowed to exist for number of years the law was vary chary in taking them away.
'They had had to deal with three weirs, Messrs. Westhead's, Messrs. Birley's, and the weir of the Navigation Company. In the interview the committee had had with Mr. Westhead he had told them that would be very willing to assist the committee to the best of his ability, but he said he must have compensation if the weir was removed, and not only compensation but a supply of condensing water guaranteed to him. The committee found that Messrs. Westhead's weir had been in existence 80 years. Messrs. Birley's weir had existed only nine years, but it had replaced a structure which had been in existence for 40 years, and he thought that any parliamentary committee would say that such water privileges could not be disturbed without great compensation.
'The weir of the Navigation Company, they found, was most formidable obstruction. The Duke of Bridgewater had obtained an Act of Parliament in 1756 authorising him to make the canal, and what an Act of Parliament had conferred he thought it would require an Act of Parliament to break through. Besides, Parliament would be likely to say that the city of Manchester had received extraordinary privileges by that canal. They had had an interview with the Navigation Company, and had urged upon them very strongly that moral obligation rested upon them to do something in aid of this project. The great objection which the committee had found to the removal of the weirs had not been so much the amount of compensation they would have to pay to the owners for the loss the weirs, but to the paying of compensation to a number of others who used the water.
'Between Birley's weir and the Pin Mill Bridge there were twenty-two users of water, who used 143,000 cubic feet of water per hour for condensing purposes, and taking ten hours per day, that brought up the consumption to nearly one and half million feet or 8,939,687 gallons of water, for condensing purposes only. If the weirs were removed, the water would run down mid-channel, and would be of no use, as there would not be sufficient of it. Where was the water to come from? At present it was dammed up by weirs, and these really formed reservoirs.
'On visiting Messrs. Westhead's during the drought of last summer they saw that there was so little water that person might have walked over the sill dry-shod, but the water was used over and over again and allowed to cool. If they destroyed the weirs the water would escape, and how could they then supply water? He did not know, except in one of two ways. They must either supply reservoirs along the sides of the river—which they could not do, as there was no land to spare—or they must bring water direct, a thing which they never projected, from Woodhead into the yards of the millowners.
'The committee had, therefore, been compelled to give up the idea of getting rid of the weirs. The next scheme which suggested itself was to have bye-washes, the cost of construction of which would amount to £80,000 or £100,000, and the total amount of this scheme, as estimated by the city surveyor, would amount to £217,000, leaving out the cost of any intercepting sewer, which would be additional £60,000. When the committee found that the cost would be so great they thought it was useless to offer it to the Council for consideration, as the scheme really meant the making a new river through the heart of Manchester, and would disturb many large properties and workshops; and, therefore, they had abandoned it.
'In considering the question how it was that the bridges and viaducts had been built over the river, they had found, from the deputy town clerk, that the Corporation were not the conservators of the river; they were only the conservators of that part of it from Birley's weir to Pin Mill Bridge, and that below the weir they had no control whatever. Before they blamed others, however, they ought to sure that they were free of blame themselves. They had had taken out the number of feet occupied by bridges and tunnels along the course of the river from Pin Mill Bridge to the outlet. The largest one was the Knott Mill tunnel of the Navigation Company, which was obtained under Act of Parliament more than century ago. Setting that aside as the largest, they had the Medlock Bridge, which spanned a distance of 150 feet; then there was the Gasworks tunnel with 430 feet, and the Hulme-street tunnel, all of which were Corporation property. Some of the worst places they had to deal with were the Hundred county bridges, which would have to be raised, and this would interfere with the present formation of the streets. The new plan they proposed was indicated in the report.... ..' 
'As to the floods prevention works it may be stated that the great inconvenience to the public, and serious loss and damage to property caused by floods, which occurred from time to time in the rivers Irwell and Medlock, led the navigation authorities to substitute Wiswall’s Patent Tilting Weirs in lieu of the old stone weirs across the river Irwell at Throstle Nest (near the principal entrance to the Jubilee Exhibition at Old Trafford), and the outlet of the river Medlock, at Knott Mill. Two other weirs, similar in construction, have just been completed on the river Medlock—one at Messrs. Westhead's works, in Sackville-street, London-road, and the other at Messrs. Birley's works, in Lower Cambridge-street. ....'. Note: 'Birley's works' was one of the Cambridge Street Mills. The fixed cast iron parts of 'Birley's' Wiswall tilting weir can still be seen from Cambridge Street (see photo).
A number of photographs, available online, show Wiswall's tilting weir at Messrs Westhead's in 1900, 1938 and, apparently disabled, in 1946   . This part of the river is no longer visible, having been culverted.
19th and 20th century photographs provide Stygian visions of a shallow, foul stream snaking through canyons of decaying, blackened brickwork, beset by weirs, incompatible with the passage of laden boats. In fact, Green's Map of Manchester & Salford shows that the landscape when surveyed (1787 - 1794) was predominantly rural. Shading on the map suggests a relatively broad, very shallow valley, doubtless providing an adequate flood plain. For a few years from the late 1780s, a stretch of the river was used by boats, taking the Duke of Bridgewater’s coal from the mines at Worsley to a point below what is now the approach to Piccadilly Station. Presumably the barges were towed upstream by horse or human power.
A 649-yard tunnel was cut from a point on the river near the Old Garratt dye works, heading east to a point near Shooter’s Brow. A horse-powered winch took coal up a shaft to Knowle & Son’s coal yard. However, by 1800 the River Medlock had risen at least 8 ft at the tunnel entrance, due to silting . The entrance to the tunnel is just visible today (see photo in entry for James and John M. Worrall).
It may seem odd that so much effort should have been applied to move coal just a mile further into Manchester from Castlefield Basin. Perhaps this emphasises the difficult in transporting freight on poor roads. Manchester is not notably hilly, but evidently there was great advantage in getting the coal to a high point before loading it on to carts, making the horses' delivery work much easier.
An early account (1827):-
'Perhaps a great proportion the present inhabitants have no idea of the state of London-Road, scarcely twenty years since. Two drums and windlasses, with geering, etc. for raising coal, then stood on the site of the present foot-path, on the north side, between Ducie-Street and Store-street. Coals were then raised from eyes or shafts, which had the appearance of two coal-pits. But the coals were not dug there, but brought in the Duke of Bridgewater's boats from Knott-Mill upon the river Medlock to Garratt, and from thence by a tunnel to this place. This unsightly machinery was taken down when the road was altered. The road was then considerably raised over Shooter’s-brook, which runs nearly under the new market house. The descent from Piccadilly to the brook was called Shooter-brow, on account of butts being erected there for the amusement of archers.'
Early Industrial Use
Green's Map of Manchester & Salford (surveyed 1787 - 1794) shows approximately 20 buildings on the Medlock's banks which appear to be for industrial use. The factory shown furthest upstream on the map was the paper and pin mill of James Meredith. Of those factories whose role is identified, six are dye works, two are cotton works, two are breweries, plus single examples of vitriol, printing, wood and corn mills.
A Case of Pollution
The following report from an 1826 newpaper starts with a somewhat obscure headline, and then makes slow progress to a conclusion, which would have greater clarity had not part of the page been illegible! Nevertheless, it does give an insight in aspects of the Manchester industrial scene at an early date.
'TURNING GAS REFUSE INTO RIVERS.
ARCHIBALD M’DONALD AND OTHERS, V. BIRLEY AND OTHERS.
This was an action brought by the trustees of the late Duke of Bridgewater against Messrs. Birley, Hornby, and Kirke, of this town, for nuisance committed by turning their gas-refuse into the river Medlock. The case stood for trial at the last spring assizes at Lancaster, but was then, by consent of the parties, referred Mr. Coltman, with power to decide the present action, and also to determine in what manner the gas-works of the defendants should, future, be regulated. A nominal verdict was therefore taken for the plaintiffs, subject to Mr. Coltman's award. Owing to various causes, the hearing of the case before the referee was delayed until the last Salford sessions; when (on the 18th January) it came on at the Star Inn. Mr. Courtenay appeared as counsel for the plaintiffs, and Mr. Armstrong for the defendants.
Mr. Courtenay opened the pleadings. The declaration stated, that the plaintiffs, were, by certain acts of parliament, entitled to the waters of the river Medlock, which ought to flow to their canal pure and undefiled; but that the defendants had put therein a quantity of gas refuse: gas-tar, ammoniacal liquor, and other impurities, whereby such waters were contaminated.-The defendants pleaded the general issue.
The learned gentleman then addressed the referee, on the case which he intended to put before him in evidence. He stated that the present subject-matter of complaint had been of very long standing; for in the year 1821, four years before the present action was brought, the solicitors of the plaintiffs wrote to the defendants, stating the unwillingness of the trustees to go to law, and expressing a wish that the annoyance might be remedied without the trouble and expense of an action. His motive for stating this fact was to shew, that there was nothing vexatious in the proceedings which had at length been adopted. The application to the defendants was dated the 4th Sept. 1821, and after recapitulating the causes of complaint, went on to state that if the practice of turning gas-refuse into the rivers was not discontinued, the plaintiffs would be compelled to adopt such legal proceedings as might be advised for putting an end to the nuisance. This application led to a correspondence between the parties, which continued for some time; but as it did not lead to the desired result, and the nuisance was continued, the draft of an act of Parliament to restrain it was prepared and submitted to the defendants and other mill-owners on the stream, but they objected to its provisions, apparently thinking they had a right to use the Medlock as a drain for carrying off the impurities which were generated at their works. Every effort having thus been made by the trustees to remedy the evil of which they complained in an amicable manner, they were under the necessity of bringing the present action to defend their undoubted rights, and put a stop, if they could, to this grievous and insupportable nuisance. In order to prove that defendants were guilty of causing it, he (Mr. Courtenay) should call a witness, who would prove that on the 8th of January, 1825, he was watching the river for the purpose of detecting any parties who might turn their gas-refuse into the river; when he saw quantity of gas-tar issuing for three hours together, out the end of a tunnel running from the defendant's works; the situation of which would be understood by reference to the plan which he held in his hand.—He was aware it would be contended by the defendants that this was a public drain, communicating with other works than theirs. This might be the case; but, that the tar which the witness saw issuing from the end of it came from their works, there could be no earthly doubt, when the following facts were duly considered:—On examining the plan three spots would be seen in Cambridge-street, representing three grates or gully-holes, communicating with the tunnel. At the lowest of these nearest the bridge, during the time the tar was issuing from the end of the tunnel, there was a very strong and insupportable stench of gas, accompanied by a very copious steam: at the second grate there was some stench and a little steam, but not so much as the first; and at the third grate, which was just beyond the defendants' works, there was neither stench nor steam at all: it was quite clear that the tar which flowed into the river must have come from the defendants’ works, or they would have been perceived at the third grate. In addition to this, he should prove that Mr. Marsland's factory was the only one having communication with the tunnel, at which gas was made; and he should call Mr. Marsland's man to prove that no tar issued from their works on the day in question, and that the factory was not then even at work at all. When he had proved these facts, he was confident the referee could come only to one conclusion, namely, that the defendants were the persons who were thus defiling the water, and that they were guilty of the nuisance with which they were charged in the declaration. He (Mr. Courtenay) was aware that the referee had had a view of the premises, which might have made an impression upon him favourable to the defendants; but he begged to remind him that, on such occasions, the premises would be prepared for the purpose, and the defendants would take good care that nothing offensive should present itself to his view. He (Mr. Courtenay) submitted that any impression resulting from such a view could not be put in competition with the positive and direct testimony which he should produce on the part of the plaintiffs. After some observations on the serious loss and expense accruing to the plaintiffs from the quantity of gas-refuse which flowed into the river; the necessity which it entailed upon them of frequently cleaning out the canal; and the noisome stench it caused there,—the learned gentleman concluded by expressing a confident opinion that the award must be in his favour. He then called the following witnesses:—
James Barnes—I was employed to watch if any body who let any gas-refuse into the river Medlock. On the 8th Jan. about two o'clock, I saw the scum of gas-tar floating on the river, and coming out from under the bridge at the bottom of Cambridge-street. There is main-sewer which opens into the river the centre of the bridge. The opening is above the surface of the water. 1 saw the injection-water from a steam-engine coming out of the tunnel into the river, and then a scum arise to the surface of the water; large blobs of tar rose up, and spread to a considerable size, and then floated down the river. I watched this, from two o'clock until half-past four or five. I went to the grate of the main sewer from in front of Mr. Birley's factory, opposite the lodge. It smelled very strong of gas and there was steam from the hot water. I then went to the second grate it smelled, but not quite so strong as the first, and there was some little steam from that also. I did not smell any thing at the third grate, I opened it with a stick, and went down on my knees, but could not smell any thing, or see any steam. The third grate is over the drain in Chester-street; but that did not appear deep enough for the main sewer. I could not see any thing but scum come out with the water; nothing but the tar that came down on the top of the water. I was there again on the 12th January, and saw the same as on the 8th: the tar coming out under the bridge, and floating for a considerable way above and below it. I smelled at the grids, and they were the same as before, a strong smell at the first; less at the second; and none at the third. The third grid six or seven feet, or better, from the main sewer. On the 12th, I saw it about an hour and a half. I took a specimen of this water. I went on the 2d. February, and on the 29th March, and saw the same. I went the week round, but generally saw it on Saturdays and Tuesdays. Mr. Edward Foulkes went with me the place on the 8th January. There are the two Marslands and Runcorns who have factories adjoining Mr. Birley's. Henry Marsland uses gas; but John does not. Cross-examined-. I do not know that Mr. Birley's condensing water comes from the river. I have seen tar floating on the river higher up, but not that time. I have been up as far as Shooter's Brook, endeavouring to trace the tar coming down. I don't know how many mills there are on the Medlock that use gas.— Re-examined —The scum floated twenty yards, up the river against the stream.
Charles Stott.—I am a clerk to Mr. Foulkes, I went with witness Barnes, on the 8th January. We saw a good deal of gas on the water, it was like oil on the surface of the water. It came under the bridge and drifted up the river and down again. There was no such appearance above. I examined the gratings, the first stunk very bad: the second a little, and the third none all. I have seen similar appearances to what I have described on the 29th January and on the 12th February. I assisted Barnes to take the samples of the stuff that floated on the water.
Mr. Edward Foulkes, Jun.—I went with the last witnesses to see the river on the 8th January. I have heard the account which they have given, and it is perfectly correct. When I saw it, the hot water was continually running out, and the tar bubbled out in large masses. It came up about the size of a thumb and spread over the water like oil.
Mr. Sothern.— I am an agent to the Duke of Bridgewater's trustees, at Worsley. I was sent for by the last witness, and saw the symptoms which he has described. This refuse is a great annoyance to the canal: it is a nuisance at our works below: the workmen have been compelled go out the warehouse. I have been compelled to close the windows of the boat on the canal. A great deal of filth comes down the river and we are obliged to clean the canal more frequently than we used to do. It comes down in great quantities especially at times of flood. The tar lies at the bottom of the water, and the oil floats the surface. It is an injury to the navigation. I have had frequent complaints from the masters of the boats, and from clerks in that warehouse.
James Hervey.— I was a maker of gas for seven months, three winters ago. I have examined samples of water which Barnes gave me: it was similar to what comes out of the of the tar-vessels in process of gas and tar making. It is the dirt and tar and water. In gas-making the vessels are generally cleaned out twice or thrice a week, and this stuff made away with; that I examined had in it a quantity of this residue: it had a very musty smell. I do not think the stuff I saw has any thing to do with the gasometer-water. The gasometer-water is very seldom discharged; not more than twice a-year. It has none of this residue in it.— Cross-examined.- I was employed as gasmaker by Mr. Ormrod. His works communicate with Shooter's Brook. His gas-refuse was turned into the main sewer, and went where it had a mind to go. Into Shooter's Brook very likely.
Mr. Heaton.— I am a manager at the Duke’s warehouse at Knot-Mill. The canal has suffered lately by the quantity of residuum accumulated there: the navigation is frequently obstructed by it, so that we cannot carry on business. In floods a great quantity of residuum and other kinds of rubbish comes down. There is a great quantity of a black tarry substance. We are obliged to clean it out very frequently, and at considerable expense. It takes from 80 to 100 men sometimes to do it. We have to clean it out perhaps half a dozen times in six months, just according to the number of floods. We are compelled to draw all the water off. I cannot exactly state the expense; perhaps £15 to £20, besides the detention of business— Q. I suppose they make a handle of that, in favour of the rail-road? A. Yes; our opponents lay hold of it in that way. There are pleasure boats upon the canal for the conveyance of passengers. The is very offensive to them, and the captains of the boats have frequently complained of it. It is also very offensive at the warehouses; Cross-examined.— There are a great many dye-works and mills upon the Medlock, and many sewers run into it. All the filth which they produce comes down the river.
Thomas Harrison.—I am a porter at Knot-Mill. The effect of the gas-tar in the canal is very bad indeed. There is very bad smell in the warehouse, and the river brings down a great quantity of filth, which we have to get out very often. The smell is sometimes so bad in the heat of summer, that we can hardly breathe in the warehouse. I have known the canal 23 years; to the best of my knowledge it requires cleaning oftener now than it did some years ago. In the stuff taken out, there is a great deal of gas-tar amongst other rubbish. Cross-examined.- The smell is the worst in the heat of summer. I know they don't make gas at that time.— Re-examined.- The old residuum smells very bad when they are getting it out of the canal.
Ralph Spooner—I have been some years conversant with gas-works. examined some samples water which Barnes shewed me. It contains substances which must have come from some gas-works. There is quantity of tar, essential oil, and ammonia, all of which are offensive. The water in gasometer-pits sometimes contains a portion of essential oil, but very little if any tar, and no ammioniacal liquor. From my experience in gas-works, I can say that the water shewn, me, contained both tar and ammonia, I never knew any gasometer water so bad; and I think it could never have come from any gasometer pit— Cross-examined.- The quantity of essential oil in the gasometer pit would depend on the care in purifying the gas; the greater the care, the smaller the quantity of oil.
Jonathan Oldfield and George Hutchinson, the masters of one of the passage boats, spoke to the offensive smell arising from the canal, and the annoyance caused to passengers.
'SECOND DAY, JANUARY 19.
A variety of papers and letters were put in, consisting chiefly of the correspndence between the parties; but they were not read. The samples of water which had been colllected by the witness Barnes, were also produced, and some the witnesses were re-examined, to prove that they contained gas-refuse. This closed the case for the plaintiffs.
Mr. Armstrong, for the defendants, said he would admit that the state of the river was quite as bad as his learned friend and his witnesses chose to represent it; but he denied that the defendants were producing any part of the nuisance, as he would be able to prove that they did not turn into the river a single condensable product generated in the making of gas. What was the case made out by the witnesses for the plaintiff? Why, that on three different occasions, something like gas-refuse had been seen coming out of drain running the defendant's factory; but no proof had been offered that it came from their works ; and he should be able to prove most distinctly, that there was no communication whatever between that drain and their gasworks; so that it could not possibly have come from them. It was true that they turned the condensing water from their old factory into this drain, but that had no communiction with the gas-works; and if any gas-refuse at all came from them, it must have been taken in with the condensing-water, which they could not help: they must turn out the water as they took it in. One of the witnesses for the plaintiffs, indeed, had explained how the water of the Medlock came to be impregnated with gas-refuse; for he admitted that he was gas-maker at Ormrod's about three years ago; and that their practice was to turnout their gas-tar, and all the offensive products of distillation, and allow them to run off into Shooter's Brook. Whether they continued that practice now, he (Mr. Armstrong) could not tell; but if they did, very likely some of the refuse which the witnesses had described, came from that source. However that might be, the defendants had taken such precautions, that no tar or other refuse could possibly escape into the Medlock, or any sewer connected with it. Mr. Armstrong then called the following witnesses:
Christopher Dunn. - I have been some time in the employ of Messrs. Birley and Co. as gas-maker. This is the fourth season I have been so employed. My directions were, to let no gas-refuse run into the river, or I should be instantly discharged. I have complied strictly with those directions. The tar and ammoniacal liquor is received from the retorts into three barrels, from which it is carried to the tar-well, which has no communication with the river. Out of that well it is pumped up, and carried away by any one who will have it; chiefly by Mr. Mutrie, who sends to fetch it. No gas-tar or refuse can possibly get either to the river or to the sewer in Cambridge-street, I remember going down into the sewer just above the factory, and found a large quantity of tar at the bottom. I got a quantity, and brought it out in a bason. I do not know where it came from; but it could not come from our works, because it was higher up the drain, and there was a strong stream of water coming down.
Henry Kimmens.— I am a carpenter, and have been ten years in the employ of Messrs. Birley and Co. I was employed in constructing the tar-pit and soughs. There no possible connexion from the tar-pit to the river, or to the sough in Cambridge-street; and no gas-tar could possibly flow into either.
Mr. Reed.—I was a manager for Messrs. Birleys fourteen or fifteen years. I know all the sewers about the factories very well. There is no connexion between the gasworks and the sewer in Cambridge-street. The sewer is higher than the gas-works; so that no tar could possibly flow into it if there was a communication.
Edward Fisher.— I am a gas-apparatus maker, in Salford, and have carried on that business for eight or nine, years. I examined the premises of the defendants in March last, and found the precautions adopted to prevent the escape of tar or other refuse very effectual and complete. I have never examined any other gas-works here so much care was exercised in condensing and purifying the gas.
Mr. John Fairweather.— I am the owner and occupier of two mills; one above and the other below Messrs. Birley and Co.'s. I have been much annoyed by gas-tar coming down the river; but there is no difference in that respect between the higher and the lower mill. The river is much worse now in summer time than it used to be. I attribute that to the quantity of water which the Water Works Company take out of it: they take it nearly all in summer. I have been through Messrs. Birley and Co.'s works: and I firmly believe there is no escape of tar from them into the river.
Mr. Courtenay briefly addressed the referee in reply, and expressed his confidence that the award must be in his favour; for, unless the witnesses he called were perjured, there was a considerable quantity of tar escaping from the end of the drain, and it could not have come from any other premises than those of the defendants. He did not impute that there was any direct connection between the gas-works and the sewer.
Mr. Coltman.- That is the great difficulty your case. I must confess it has made a strong impression on my mind. [Note: parts of text obscured here, indicated by question marks] Mr. Courtenay submitted that the tar might be ? up, and turned through some pipe into ? contended it did not lie upon him to prove ? in which it was conveyed from the gas-works ? it was sufficient that he had shewn its ? would entitle him to an award in his favour.
On the following day, at the request of ? counsel, the referee had another view ? when a drain was discovered, leading ? to the river, but not communicating with Cambridge-street. At the head of the drain ? gas-tar; and on removing a few shovelfuls ? of the tar flowed down the drain and r? On the following day another view was taken at the request of the defendants' counsel; when the ? drain was opened up, and the measures taken for stopping it were shewn to the referee.
Mr. Coltman took the papers with him to London ? a few days ago, made his award, directing that ? should be entered for the plaintiffs, damages one shilling[?] (which carries costs); and that the drain discovered at the last view but one, should be effectually closed.'
Sources of Information
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