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Overton reservoirs 1-8 and associated channels, Clyde Muirshiel Park

A Scheduled Monument in Inverclyde South, Inverclyde

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Latitude: 55.9321 / 55°55'55"N

Longitude: -4.7963 / 4°47'46"W

OS Eastings: 225414

OS Northings: 674536

OS Grid: NS254745

Mapcode National: GBR 0B.Z8GQ

Mapcode Global: WH2MH.9596

Entry Name: Overton reservoirs 1-8 and associated channels, Clyde Muirshiel Park

Scheduled Date: 2 September 2011

Source: Historic Environment Scotland

Source ID: SM12810

Schedule Class: Cultural

Category: Industrial: gas, electrical, water, sewage and other utilities; Secular: bridge

Location: Greenock/Inverkip

County: Inverclyde

Electoral Ward: Inverclyde South

Traditional County: Renfrewshire


The monument comprises a series of eight auxiliary reservoirs and associated dams, sluices, sluice houses, footbridges, channels and a workman's bothy that form part of a larger water system built to provide the industries of Greenock with a source of water power and also to provide domestic water. The monument was designed by Robert Thom and built between 1825 and 1827 by Shaw's Water Company. The eight auxiliary reservoirs acted as collecting basins for hill run-off to provide a reserve against drought and a means of preventing flood damage. The monument became obsolete in 1971 when the aqueduct they fed was replaced by a tunnel. The monument is located in high moorland to the south of Greenock between around 190m and 270m above sea level. The monument was first scheduled as three separate monuments in 1998. It is being rescheduled as one monument both to facilitate easier management and maintenance, and also to update the scheduled area and associated documentation.

Reservoir 1 is roughly triangular shaped and is the southernmost of the eight reservoirs, centred on NS 2406 7292 at around 260m above sea level. The N edge of the reservoir measures around 190m in length. The NE to S side measures around 270m while the S to NW side measures 220m. It has an earth-and-gravel, boulder-faced dam at the NW, about 60m long with an exposed sluice mechanism that has been deliberately breached by a V-shaped gap. A cast iron covered holding tank and pipe mark the location of the sluice house on the NW side of the dam. A rock-cut overflow channel, known as a spillway, with partial masonry facing, runs downhill north for around 440m from the dam to Reservoir 2. This reservoir, as are all the reservoirs, is lined with a mixture of puddled clay and stones, designed to render it vermin proof.

Reservoir 2, of irregular plan, is N of Reservoir 1, centred on NS 2394 7340 at around 225m above sea level. It measures around 210m WNW-ESE by up to 95m transversely. It has a dam of similar construction to that at Reservoir 1 at the NE, measuring some 120m in length, and also with an exposed sluice mechanism and breached by a V-shaped gap. A concrete cover over the sluice outlet marks the site of a former sluice house. A spillway channel made of stone-lined concrete is located in the centre of the dam and runs around 350m N downhill to the main Greenock Cut aqueduct.

Branching off from the spillway channel linking Reservoirs 1 and 2, at NS 2399 7319, is a more substantial feeder channel heading NW to Reservoir 3. The W end of this channel has been created by digging out and enhancing a natural stream bed over a distance of 575m. The channel has a width of 1.5m with a parallel bank 1.5m wide on the NW side. The E end of the channel reverts to the natural stream.

Reservoir 3, of irregular plan, is centred on NS 2455 7394 at around 215m above sea level. It measures around 380m NE-SW by up to 155m transversely. It has an angled dam on its N and NW sides of similar construction to that at Reservoirs 1 and 2. The N length of this dam measures around 120m. The NW part is lower in profile and is about 140m long. The spillway channel is located at the angle where the two dam banks meet. It appears as a concrete-lined channel, probably initially rock-cut. A supplementary channel joins the main spillway channel from a point around 35m E along the dam, where the sluice house is located. The spillway channel runs N for 490m to join the main aqueduct and appears to use a pre-existing stream. The channel is crossed by a masonry footbridge at NS 2460 7424.

A feeder channel, known as 'The Wee Cut', runs ENE from the overflow channel of Reservoir 3 for around 920m along the 190m contour, where it joins the south end of Reservoir 5. The channel is entirely artificial and collected water from the surrounding area. It is stone-lined, with two section embankments on the N side, and is crossed by five masonry footbridges at NS 2495 7433, NS 2510 7433, NS 2526 7438, NS 2534 7439 and NS 2540 7445. A masonry bothy, measuring 5.65m E-W by 3.8m transversely, stands adjacent to the channel on its N side at NS 2534 7440.

Reservoir 4, of irregular plan, is centred on NS 2513 7445 at around 190m above sea level. It measures around 160 m N-S by up to 155m transversely. It is dammed on the W and SW side with dams measuring a total of 195m in length. A sluice house is located to the NW at NS 2508 7451, through which water flows NW and downhill for around 415m in a stone-lined channel to the main aqueduct. Two masonry footbridges cross the channel at NS 2501 7452 and NS 2476 7457. Some 40m SW of the sluice house the spillway channel runs NNW from the dam to join the same stone-lined channel. An additional spillway channel runs from the E end of Reservoir 4 east into the SW end of Reservoir 5. This channel is around 155m in length and is spanned by a masonry footbridge at NS 2535 7447.

Reservoir 5, irregular on plan, is centred on NS 2544 7454 at around 205m above sea level. It measures around 190m NE-SW by 150m transversely. A dam, made of alternating layers of peat and clay and faced with stone, is located at the N end and forms the foundation of a road running to the north of Reservoir 4. The sluice outlet is located at the SE of the dam. There is a concrete-lined exit channel that extends for 470m to the NE where it joins the Greenock Cut aqueduct at Hole Glen. There are three masonry footbridges over the channel at NS 2567 7463, NS 2580 7463 and NS 2593 7473.

Reservoir 6, of irregular plan, is centred on NS 2620 7433. It measures around 170m NE-SW by up to 70m transversely. The dam is on the NE and projecting from it is a pier. An additional stone-covered earthen bank has been constructed on the NW side. Both the dam and earth bank support a tarmac road. The sluice mechanism is located on the NW. The sluice house, constructed over the sluice outlet, is built of rubble with a domed roof and dressed stone doorway. A spillway channel is located around 45m to the NE. Both channels join a natural stream at NS 2616 7439, which runs downhill to the NNW for around 350m where it joins the Greenock Cut aqueduct. An underground pipe from the north of Reservoir 6 extends 225m to Reservoir 8.

Reservoir 7 is also known as New Yetts Reservoir. It is of irregular shape and is centred on NS 2633 7396. It measures around 210m ENE-WSW by up to 205m transversely. A 200m-long dam is located across the N end. The dam is constructed of alternating layers of alluvial earth and gravel and is faced with interlocking boulders. A 2m-wide stone-lined overflow channel cuts through the E end of the dam and flows through a concrete pipe under a modern road and masonry bridge at NS 2635 7410. The sluice mechanism and channel are located around 70m to the SW of the spillway channel. Both channels meet to the N of the reservoir at NS 2627 7415 where they flow into a natural stream. The watercourse runs N for around 160m into the S end of Reservoir 6.

Reservoir 8, of irregular plan, is centred on NS 2648 7462. The reservoir measures around 170m NE-SW by up to 85m transversely. There is a stone-clad earth dam on the NE side and a secondary bank around the NW corner. There is no visible sluice mechanism and the water appears to flow into a concealed pipe with inspection covers near the centre of the dam. A small, empty, holding reservoir is located 45m to the NE. This measures around 40m NE-SW by up to 30m transversely and has a concrete dam on the NE and NW side. An area of hard-standing and the remains of a rectangular filter structure, measuring 10m NE-SW by 5m transversely, are located between the two reservoirs. A stone-lined spillway channel 0.5m wide runs from the NE corner of Reservoir 8 to the E side of the holding reservoir. From the holding reservoir, the spillway channel continues under a tarmac road and underground N for around 60m to the main Greenock Cut aqueduct.

The area to be scheduled is irregular in plan, to include all reservoirs, dams, sluice mechanisms, sluice houses, bridges, pier and bothy, spillways and ancillary watercourses, as described above and as shown in red on the accompanying map. Around the dams and sluices, the scheduled area includes an area within which evidence relating to their construction, use and abandonment may survive. The scheduled areas of the basins of Reservoirs 1 and 2 comprise those areas formerly covered by the maximum extent of water. The scheduled areas of Reservoirs 3, 4, 5, 6, 7 and 8 comprise the areas formerly covered by the maximum extent of water. The scheduled area of Reservoir 5 extends up to but excludes the unmade road passing to its N. The scheduled area of Reservoir 8 extends up to but excludes the road on the NE side. The scheduled area of all associated water courses described extends to a distance of 2m from the edge of the channel, or the outer edge of the embankment where present, for the support and preservation of the monument. Specifically excluded from the scheduled area are all made road surfaces and the above-ground elements of all fences, dykes and telegraph poles, to allow for their maintenance. Also excluded from the scheduled area are any sluice mechanisms installed since 1972.

Source: Historic Environment Scotland

Statement of Scheduling

Cultural Significance

The monument's cultural significance can be expressed as follows:

Intrinsic characteristics

Shaw's Water Joint Stock Company was incorporated on 10th June 1825 and the system was officially opened on 16 April 1827. The monument is a significant part of an extensive and ambitious early 19th-century civil hydraulic engineering scheme. The system utilised and added to existing water courses in order to take water from the high moorland above Greenock through the town to provide water power for industry and domestic water.

Most elements of the auxiliary reservoirs and channels are well preserved and actively maintained, and are clearly visible and easy to understand on the ground. The monument informs our understanding of a large and innovative scheme to manipulate the landscape to harness rainwater and to provide water for power and domestic supply. The monument has the capacity to further our knowledge of the construction methods of the reservoirs and associated dams and sluices of the early 19th century. The duration of use of the monument, in excess of 150 years, means the monument also has the potential to retain information on the refinement and development of the system as technological advances were made, as well as to illustrate the shortcomings of the system which led to its eventual abandonment.

Contextual characteristics

Water for Greenock was supplied by a number of wells and streams until a piped water supply was designed by James Watt and installed in 1773. However, Greenock expanded rapidly and the population trebled between 1780 and 1820, and demand for water soon outstripped supply. A new system relying on an aqueduct 9 km long to pipe water collected from the high ground to the south of the populated area was designed. The Great Reservoir, Loch Thom, was the start of the aqueduct and the main source of water, but additional water was fed into the system as necessary from eight auxiliary reservoirs, each located within its own valley and each connected directly to the aqueduct. The flow from the auxiliary reservoirs was controlled through innovative automatic sluices. The system had a capacity of 21,000 cubic feet of water per day and powered many industries in Greenock. The supply of domestic water was less successful until the construction of the Gryfe Reservoir in 1872.

In Greenock, the water was channelled through the town along two routes. At set levels along the length of these routes, sites, known as falls, were available for rent by water powered industry. These industries grew to include paper-making, distilling, textile, rope-making, flour, and sugar refining amongst others. Among these industries was the spinning works of Neil, Fleming, Reid and Co., where a water wheel in excess of 21.3m and known as the 'Great Wheel' operated. The remains of the lines of the falls can be seen at various locations in Greenock, as well as many of the former industrial buildings.

This is of a rare type of industrial monument and there are few comparable systems for the organisation of water power in Scotland. Thom's earlier scheme on Bute had canalised water from the south and west of the island to Loch Fad, and then by lade to the sea, and increased water power on the island from 30hp to 70hp, equivalent to steam power. It was on Bute that Thom designed self-activating sluices to lessen waste of water, and also where he implemented auxiliary reservoirs to counteract periods of heavy rainfall. The contemporary 4 mile-long Leven Cut in Fife was constructed with the dual aims of decreasing the levels of Loch Leven and thereby increasing agricultural land and also providing water power for mills and industries downstream. Comparison between these systems can increase our understanding of technological advancement.

Associative characteristics

The monument was designed by the hydraulic engineer Robert Thom (1774-1847) at the height of the Industrial Revolution and its importance is enhanced by these associations. Thom was educated at the Andersonian Institute, Glasgow, and before working in Inverclyde worked on maximising power to the cotton mills of West Lothian and Rothesay, Bute. The principal reservoir of the Greenock Scheme is named after Thom. The Greenock scheme has been described as Thom's finest achievement, where he demonstrated his innovative thinking on water engineering. As an example of his work the monument has the capacity to further our understanding of hydraulic engineering and its development in Scotland and the contribution of Thom to that progress.

The monument is intimately linked to industrial progress and expansion in Greenock. It was the main conveyor of water to the town for over 150 years and its ability to satisfy the demand of a growing industry contributed to the success story of the town during this period.

The monument's importance is also enhanced by the survival of extensive documentation including maps and plans. This records details of the monument from its initial conception through to its use, adaption and abandonment.

National Importance

The monument is of national importance because it has an inherent potential to make a significant addition to our understanding of the past, in particular the Industrial Revolution and the study of hydraulic engineering in Scotland, and development of water provision for drinking and industry in 19th-century Greenock. The monument demonstrates the significant impact that technology had on the Scottish landscape during this period and the particular contribution of Robert Thom to hydraulic innovation. The well-preserved, complex system of reservoirs, dams, sluices and associated channels is an important survival of a defining period in industrial and civic history, not only in Inverclyde but across Scotland and further afield. The loss of the monument would impede our understanding of industrial development at a regional, national and international level.

Source: Historic Environment Scotland



This monument was previously scheduled as three monuments:

AMH/7506/2/1 Loch Thom-Overton Water Cut, Reservoirs 3, 4 and 5

AMH/7501/2/1 Loch Thom Overton Water Cut, Reservoirs 6, 7 and 8

AMH/7498/2/1 Loch Thom-Overton Water Cut Reservoirs 1 and 2

These have all been technically descheduled to create the new combined scheduling. All files associated with the old numbers are to be closed.

Parts of this monument are recorded by the Royal Commission on the Ancient and Historic Monument of Scotland under the numbers NS27SE 57.01, NS27SE 57.02 and NS27SE 59.


Kirkdale Archaeology 2007, The Greenock Cut: Archaeological Recording 2006-2007, unpublished report.

The Gazetteer for Scotland, Greenock Cut

Lynn, J 2005, Greenock Cut, PowerPoint presentation, Inverclyde Council.

Source: Historic Environment Scotland

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