Later Years
Mt Evelyn aqueduct trail
In the 1960's, with the increase of residential development around the aqueduct - in the Mt Evelyn area in particular - and with the increased pollution or contamination risks from an open adqueduct, parts of the Mt Evelyn section of the aqueduct were closed and replaced by underground pipelines (the entire Mt Evelyn section of the aqueduct was finally decommissioned in February 1972). Much of the original open channel was filled in the 1970's but portions of it still remain.
By 1968 the MMBW had developed an ambitious plan to meets Melbourne's future water needs and over the next decade a number of major new storages were built; including Greenvale, Cardinia, Thompson and Sugarloaf.
Whilst the water coming from the O'Shannassy watershed was, and still is, vitally important to Melbourne, the ageing aqueduct was nearing the end of its days. A number of major landslips had caused severe damage to the aqueduct over a period of years (the main ones being at the Dee Road slip and Marysville slip, near Warburton) and whilst they had been repaired, the repairs were now failing. In addition, the cement channel which had for so long stood the test of time was beginning to deteriorate and break up - damage from wild deer, wombats, tree roots, falling trees and water seepage were taking their toll.
On an increasing number of occasions, there were major breaches in the channel causing millions of litres of water to come rushing down the moutainside like a tidal wave, carrying everything in its path. Considerable damage to property and homes was caused and whilst, fortunately, no lives were lost, this could easily have been the case. As the risks increased and the cost of repairs escalated, landowners near the aqueduct began to lobby for its closure and with so many alternatives available (piping the entire aqueduct underground was the preferred option) the long term future of the aqueduct was being seriously questioned. In particular, the very costly and labour-intensive nature of the aqueduct's operation, with its extensive "army" of caretakers all performing management of the aqueduct system manually, was in doubt.
After 100 years of service to the people of Melbourne, the MMBW merged with a number of smaller urban water authorities in 1991 to form a new organisation called Melbourne Water. The new organisation brought a fresh, new, more modern approach (they were able to break away from the 100 year old traditions and historical attachments of the Board) and the end of the open aqueduct was clearly on the cards. Increasingly, caretakers were laid off and old infrastructure was replaced with new, more automated versions. In January 1996 Melbourne Water announced that the aqueduct would be closed in December of that year. Poor water quality and increasing safety concerns were cited as reasons for the closure. Eventually, the open aqueduct was closed in its entirety in December 1996, being replaced by large undergound pipes to carry the water from O'Shannassy to Silvan, via a more direct route. The O'Shannassy aqueduct had served Melbourne well for 82 years.
The aqueduct channel remained in a closed catchment, protected by Melbourne Water, and the walkway beside the aqueduct became a popular (and beautiful) walking and cycling trail for locals (and a popular access trail for illegal deer shooters at night).
As the years progressed, with little maintenance of the remnants of the once-great aqueduct and related infrastructure, the aqueduct fell increasingly into disrepair and today relatively little of of earlier appearance or purpose is generally understood or appreciated. Many of the buildings and infrastructure has been removed or disappeared and much of the open channel has now been consumed and overtaken by the bush. The former caretakers have long since retired or passed on. Only the track beside the aqueduct remains in good condition.
By 1968 the MMBW had developed an ambitious plan to meets Melbourne's future water needs and over the next decade a number of major new storages were built; including Greenvale, Cardinia, Thompson and Sugarloaf.
Whilst the water coming from the O'Shannassy watershed was, and still is, vitally important to Melbourne, the ageing aqueduct was nearing the end of its days. A number of major landslips had caused severe damage to the aqueduct over a period of years (the main ones being at the Dee Road slip and Marysville slip, near Warburton) and whilst they had been repaired, the repairs were now failing. In addition, the cement channel which had for so long stood the test of time was beginning to deteriorate and break up - damage from wild deer, wombats, tree roots, falling trees and water seepage were taking their toll.
On an increasing number of occasions, there were major breaches in the channel causing millions of litres of water to come rushing down the moutainside like a tidal wave, carrying everything in its path. Considerable damage to property and homes was caused and whilst, fortunately, no lives were lost, this could easily have been the case. As the risks increased and the cost of repairs escalated, landowners near the aqueduct began to lobby for its closure and with so many alternatives available (piping the entire aqueduct underground was the preferred option) the long term future of the aqueduct was being seriously questioned. In particular, the very costly and labour-intensive nature of the aqueduct's operation, with its extensive "army" of caretakers all performing management of the aqueduct system manually, was in doubt.
After 100 years of service to the people of Melbourne, the MMBW merged with a number of smaller urban water authorities in 1991 to form a new organisation called Melbourne Water. The new organisation brought a fresh, new, more modern approach (they were able to break away from the 100 year old traditions and historical attachments of the Board) and the end of the open aqueduct was clearly on the cards. Increasingly, caretakers were laid off and old infrastructure was replaced with new, more automated versions. In January 1996 Melbourne Water announced that the aqueduct would be closed in December of that year. Poor water quality and increasing safety concerns were cited as reasons for the closure. Eventually, the open aqueduct was closed in its entirety in December 1996, being replaced by large undergound pipes to carry the water from O'Shannassy to Silvan, via a more direct route. The O'Shannassy aqueduct had served Melbourne well for 82 years.
The aqueduct channel remained in a closed catchment, protected by Melbourne Water, and the walkway beside the aqueduct became a popular (and beautiful) walking and cycling trail for locals (and a popular access trail for illegal deer shooters at night).
As the years progressed, with little maintenance of the remnants of the once-great aqueduct and related infrastructure, the aqueduct fell increasingly into disrepair and today relatively little of of earlier appearance or purpose is generally understood or appreciated. Many of the buildings and infrastructure has been removed or disappeared and much of the open channel has now been consumed and overtaken by the bush. The former caretakers have long since retired or passed on. Only the track beside the aqueduct remains in good condition.
The O'Shannassy Aqueduct Trail
Tammy Lobato MP and community members at the "handover" of the aqueduct
The Mt Evelyn portion of the aqueduct has been used as a walking and recreational trail for many years, commencing in 1972.
A major milestone for much of the remainder of the aqueduct occurred in June 2006 when Melbourne Water officially handed control of the aqueduct over to Parks Victoria. The occasion was marked by a handover ceremony chaired by State MP Tammy Lobato and local community leaders on the aqueduct site near Warburton.
Parks Victoria immediately began planning for development of the approximately 30 kilometres of aqueduct trail that was to be under their control.
Melbourne Water retains control of the O'Shannassy Reservoir and Silvan Dam, both of which remain in full operation today, still supplying water to Melbourne.
A major milestone for much of the remainder of the aqueduct occurred in June 2006 when Melbourne Water officially handed control of the aqueduct over to Parks Victoria. The occasion was marked by a handover ceremony chaired by State MP Tammy Lobato and local community leaders on the aqueduct site near Warburton.
Parks Victoria immediately began planning for development of the approximately 30 kilometres of aqueduct trail that was to be under their control.
Melbourne Water retains control of the O'Shannassy Reservoir and Silvan Dam, both of which remain in full operation today, still supplying water to Melbourne.
Melbourne Water manages the ten Melbourne reservoirs outlined in the table below. Total storage capacity is 1,810,500 megalitres (ML).
Yan Yean (1857): 30,000 ML
Maroondah (1927): 22,000 ML
O'Shannassy (1928): 3,000 ML
Silvan (1932): 40,000 ML
Upper Yarra (1957): 200,000 ML
Tarago (1969): 37,500 ML
Greenvale (1971): 27,000 ML
Cardinia (1973): 287,000 ML
Sugarloaf (1981): 96,000 ML
Thomson (1983): 1,068,000 ML
Yan Yean (1857): 30,000 ML
Maroondah (1927): 22,000 ML
O'Shannassy (1928): 3,000 ML
Silvan (1932): 40,000 ML
Upper Yarra (1957): 200,000 ML
Tarago (1969): 37,500 ML
Greenvale (1971): 27,000 ML
Cardinia (1973): 287,000 ML
Sugarloaf (1981): 96,000 ML
Thomson (1983): 1,068,000 ML
Postscript...
Aqueduct during the 2006 pigging project
As a small postscript, part of the old aqueduct near O'Shannassy Weir came into use for a brief period during the 'pigging' (cleaning) of the pipes from O'Shannassy Reservoir in 2006.
Build up inside the pipes over time had reduced the water flow from O'Shannassy considerably and it was determined that the most cost effective option was to clean the pipes (rather then duplicate or replace them).
However, this meant blocking the pipes and shutting off water flows for a period of time. The abandoned O'Shannassy aqueduct was used as temporary storage basin the receive water discharge during pigging. A series of permeable weirs were installed at 100m intervals along the aqueduct to enable water to pass, but trap sediment. An impermeable weir was installed some 400m from the stilling basin to prevent waters flowing into the continuing aqueduct length.
The pigging project was a success and the pipeline flow capacity was markedly increased.
Build up inside the pipes over time had reduced the water flow from O'Shannassy considerably and it was determined that the most cost effective option was to clean the pipes (rather then duplicate or replace them).
However, this meant blocking the pipes and shutting off water flows for a period of time. The abandoned O'Shannassy aqueduct was used as temporary storage basin the receive water discharge during pigging. A series of permeable weirs were installed at 100m intervals along the aqueduct to enable water to pass, but trap sediment. An impermeable weir was installed some 400m from the stilling basin to prevent waters flowing into the continuing aqueduct length.
The pigging project was a success and the pipeline flow capacity was markedly increased.