Recently following a visit to Loch Katrine I got to thinking about Glasgow’s water supply and thought it would make the basis for a good project. I’ve put together a basic time line and some detail on the major structures, this was done using the info on SCRAN, RCAHMS and a few other sources. I’ve included some pictures of those at the north end of the system as these may be less familiar to most folk, but I’d like to see pictures of any structures by other members. Any additional detail or corrections would be interesting, especially on how the flow of water is controlled, the junctions between the two aqueducts, how the “siphons” work and current capacities.
Most of the structures are relatively easy to visit, however a word of caution they are generally slippy, isolated and therefore very dangerous, there will be no one around to pull you out if you fall in, meaning you could end up very drowned!
There is a really good PDF on the RCAHMS website which gives some great background on the system and describes a recent survey of the structures carried out during the 2001 works at Mugdock when an additional underground reservoir and modern treatment works were added. I’ve lifted text from this and SCRAN where appropriate.
The old SCRAN pictures are also well worth a look, as are some of the aerial RCAHMS ones especially of the inlets and outlet on Loch Katrine and Loch Arklet.
The course of both aqueducts can be partially traced using 1:25K OS maps and Google earth, however it can be confusing as it’s difficult to determine what structures belong to each one. If anyone can do an accurate Google earth overlay or show them plotted on an OS map that would be good.
If anyone is interested I see MK has posted details of a couple of related talks at the Mitchell over on the What’s On thread.
15 Oct 6:30pm 150 Years of Glasgow's Water Supply
10th Nov 6pm The Water Supply of Glasgow:Ancient Discoveries
Loch Katrine Water Supply System Timeline
1853-54 Initial scheme designed by JF Bateman, Loch Katrine Achray dam and aqueduct from Loch Katrine to reservoir at Mugdock and associated gauging and filtration works. Loch Venachar and Loch Drunkie dammed to provide compensation waters to the River Teith.
1855 First Act passed and construction started.
1859 Loch Katrine scheme opened by Queen Victoria.
1885 Second Act passed to increase the level of Loch Katrine, build a second aqueduct and create a new reservoir at Craigmaddie, east of Mugdock.
1896 Craigmaddie Reservoir completed.
1901 Second aqueduct completed.
1902 Loch Arklet bill passed to build a dam and divert the water to Loch Katrine via a tunnel and associated inlet and outlet structures on Loch Arklet and Loch Katrine.
1903 Glen Finglas Act passed to allow the water from Glen Finglas to be diverted to Loch Katrine, not taken up until the 50’s.
1909 Loch Arklet dam construction started.
1914 Loch Arklet dam and associated works completed.
1019 Act to further raise Loch Katrine level passed.
1929 Level of Loch Katrine raised by increasing the height of Achray dam and the dam around the inlet for the aqueducts.
1958 Glen Finglas tunnel to Loch Katrine completed.
1965 Glen Finglas dam completed.
Details of some of the major structures
Loch Katrine, Achray Dam
The river Achray is the natural outlet at the eastern end of the loch. Sluices for controlling the water level, a waste weir and a salmon ladder were all built into the dam.The dam originally had four sluices (1855 Act) but this was increased to nine when the water level of Loch Katrine was raised in the aftermath of the 1885 Act. A further phase of modification raised the level again in the period 1919-29. A concrete coffer dam and gates were added during WWII to help protect the supply should the main dam be damaged by bombing. There are currently 13 sluices of which six have gates, the sluices and their controls are by Glenfield Co., Hydraulic Engineers, Kilmarnock. Some are also embosed with GCWW, Glasgow City Water Works.
Loch Katrine, Aqueduct Inlets at Royal Cottage
This is just along the south shore from Stronachlachar, at the point at which the aqueducts leaves the loch. 'Royal Cottage' is so-called because Queen Victoria had lunch there on the day in 1859 when she opened the waterworks, it now stands empty.
There are two separate inlets both of similar design and now significantly below the level of the loch as a result of its level having being raised several times. The inlet on the left (west) is the later of the two. Both are protected by a masonry dam completed in 1929 with a number sluices, build by Glenfield Kennedy Ltd Kilmarnock, to control the flow of water into each.
Loch Arklet Dam
Loch Arklet Dam was built 1909-1914. This concrete dam is 350 yards in length and is faced with Annan freestone, it is 35ft in height and 11ft in depth at the top. There are two valve houses that regulate and ensure that the amount of water passing over the dam is at least the amount of water specified by the Act of Parliament authorizing the construction of this dam. This is known as the compensation supply.
Loch Arklet Tunnel Inlet and Outlet
The intake compound or structure for channelling water into the reservoir, is 'sunk' into the east end of Loch Arklet. There is a valve on the inlet sluice to control the flow that is similar in design to the intakes at Royal Cottage. The outlet, with its crenellated detail, discharges from the Loch Arklet tunnel into several gauge basins. It has a masonry stepped waterfall cascade with a walkway with original iron-fencing of typical Glasgow Corporation Waterworks design. The water channel leading from the cascade has masonry walls and a rubble base.
Loch Vennachar dam and sluice house
One of the most controversial aspects of the new waterworks scheme was that it would reduce the flow of water into the River Teith, which flows out of Loch Vennacher, and this in turn would reduce the flow of water to the River Forth. Part of the scheme was therefore the dam on Loch Vennacher which was used to feed a steady flow of compensating water into the River Teith. The sluice house is at the south end of the dam and contains a series of sluices which regulate the flow. Loch Drunkie in the hills to the south of loch Vennachar has two earthen dams and supplys additional compensation water.
25.75miles long, 8’ wide 8’ high with an arched roof and a capacity of 40 million gallons a day. It runs south from Loch Katrine, turns along the south side of Loch Chon, through the Loch Ard forest, over the Duchray water, then runs south passing north east of Drymen and between Balfron and Killearn before running through Strathblane and into the Mugdock resevior. For most of its distance it is underground but its builders did make the use of a number of aqueduct bridges, tunnels and piped (siphon) sections, most notably:-
The Culegarten aqueduct bridges which carry the water across small ravines and burns in the area south of Loch Ard
The Duchray Bridge seems to be two separate bridges of different dates but I can’t work out the detail here as I’m sure the latter aqueduct does not cross the river here.
Near Duntreath Castle Clashmore, the aqueduct is a tunnel, blasted through rock, which carries the water directly.
River Endrick bridge, the aqueduct was originally was tunnelled under the River Endrick at a ford at this point, but this was considered to risk damage if the river were to flood. A bridge gave greater access and the added benefit of an improved crossing for road traffic.
Ballewan Glen bridge caries the aqueduct from Loch Katrine across a ravine at Blairgar, near Blanefield, it is constructed of a single span of fifty feet, fifty two feet above the stream below.
23.5 miles long 10’ wide concrete lined or 12’ wide unlined, 9’ high with an arched roof and a capcity of 70 million gallons a day. This runs parallel with the original aqueduct for most of its route although sometimes takes a more direct course because its builders were able to make use of the newly invented dynamite making tunnelling easier. One of the notable structures on its route is the stone built aqueduct over the River Duchray someway upstream of the 1855 bridge mentioned above.
During construction of the 1895 aqueduct in order to carry out the work steadily in sections, it was necessary to build junctions between the aqueducts at various stages. Initially, there were seven points of connection. At completion, these junction chambers were used to isolate sections of either aqueduct for maintenance, repair and improvement, thereby minimising disruption to total supply, if anyone knows where these are or how the work I’d be interested.
The reservoirs at Mugdock and Craigmaddie both have aqueduct outlets very similar in design to the inlets at Loch Katrine. Both flow into “gauging” basins where the quantity of water entering the reservoir is measured or 'gauged', also any silt in the water is allowed to settle entering the main body of the reservoir. The only treatment which the water received in the original scheme was straining through a copper mesh, first as it left the Loch, and, again, at the reservoir before it was fed into the water mains. At the reservoirs the screening plant structure, which was designed and supplied by Glenfield and Kennedy, can still be seen, the screens themselves are in a chamber sunk into the ground.
Glen Finglas Dam and Tunnel
To further increase capacity in the system a 2.5 mile tunnel was built to divert water from the river Turk, in Glen Finglas, to Loch Katrine, this was opened in 1958. In 1965 a dam was completed to utilise the whole of the Glen Finglas catchment area and as part of the dam a 0.5MW hydro electric turbine was installed. As the tunnel is a free flowing, the turbine is used to make use of the available head created by the dam.
On my travels I came across a couple of GCWW stamped items and also noted that P&R Flemming of Glasgow seem to have got the whole contract for the original fencing around all the structures.