Description
Loch Lomond And Trossachs National Park Planning Authority
James M Gale, 1902, possibly incorporating circa 1857 fabric; extended 1919. Low-lying masonry dam with 13 sluice openings between narrow projecting piers, over-spill weir with iron footbridge above, and fish ladder. Bull-faced sandstone masonry with polished ashlar dressings; some concrete slabs to outflow steps at rear.
FURTHER DESCRIPTION: 13-bay sluice section to right, 4 left bays of which have segmental-arched sluice openings (other openings below water line); paved walkway above with standard GCWW railings; sluice operating machinery. 13-basin fish ladder adjoining battered wall to outflow side; each basin with segmental-arched opening to corresponding sluice. Stepped concrete outflow beyond fish ladder. Ashlar-coped weir section to left with iron footbridge above; sloped, paved outflow section. Stepped masonry wing-walls.
Statement of Special Interest
The eastern end of the dam crosses over into Callander parish.
A good early 20th century sluice dam which is an important element of the Glasgow Corporation Water Works system from Loch Katrine (see below for significance of the scheme as a whole). The dam was erected as part of the initial 1855 scheme, but was largely rebuilt when the level of Loch Katrine was raised in 1902. It was further extended in 1919 when the water level was raised again. The dam therefore has particular interest in evidencing the gradual expansion of the water-supply scheme.
The purpose of the dam is to control the flow of water from Loch Katrine to Loch Achray (hence the name, Achray Dam). Loch Katrine originally emptied through the Achray Water to Loch Achray and on to Loch Venachar. The controlled flow through the dam prevents the Achray Water from drying up, allows salmon to access Loch Katrine, and also creates a useful overflow function for the loch.
The original dam, built circa 1857, had 4 segmental-arched sluice openings, an over-spill weir, and fish ladder that was at right-angles to the dam and similar to the one at Loch Venachar dam. From 1885 onwards work was carried out to double the capacity of the aqueduct conduit from Loch Katrine to the reservoirs at Milngavie and the water level in the loch therefore needed to be raised to meet the extra demand. The dam seems to have been largely rebuilt in its present form to achieve this in 1902. In 1919 it was heightened and extended from 9 to 13 sluices to accommodate a further raising of the water level.
The Glasgow Corporation Water Works system, which brings water down to Glasgow from Loch Katrine, was admired internationally as an engineering marvel when it was opened in 1860. It was one of the most ambitious civil engineering schemes to have been undertaken in Europe since Antiquity, employing the most advanced surveying and construction techniques available. The scheme represents the golden age of municipal activity in Scotland and not only provided Glasgow with fresh drinking water, thereby paving the way for a significant increase in hygiene and living standards, but also a source of hydraulic power that was indispensable to the growth of Glasgow's industry as a cheap and clean means of lifting and moving heavy plant in docks, shipyards and warehouses. The civic pride in this achievement is visible in every structure connected with the scheme, from the neatly-detailed gates and railings along its route, to the massive masonry structures and iron troughs that carry the conduit and, in most cases, have withstood without failure or noticeable deterioration the daily pressure of many millions of gallons of water for well over 100 years.
Glasgow's Lord Provost, Robert Stewart (1810-66) was the driving force behind the implementation of a municipally-owned water scheme to provide clean water to Glasgow's rapidly increasing population. Loch Katrine was identified as a suitable supply and after some objections from various parties, an Act of Parliament authorising the scheme was passed in 1855. The scheme was built in two main phases following this Act and another 1885. The 1855 scheme was opened by Queen Victoria in 1859 and was fully operational by 1860.
John Frederick Bateman (1810-1889) was chosen as the engineer for the scheme and construction work commenced in 1856. Bateman was to become one of the world's most eminent water engineers, and worked on a number of other water supply schemes in Britain, Europe and Asia. He was assisted by James Morrison Gale (1830-1905), who on the completion of the initial scheme in 1859 was appointed Water Engineer for the City of Glasgow, a post he held till 1902. Gale was responsible for over-seeing the incremental expansion of the first scheme during the 1860s and '70s and the building of the second aqueduct from 1885 onwards.
Listed following the thematic review of Loch Katrine water supply system in 2008.