Enoggera Reservoir

General

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Also known as

Enoggera Dam

Classification

State Heritage

Register status

Entered

Date entered

3 July 2007

Type

Utilities—water supply: Dam/reservoir

Themes

2.5 Exploiting, utilising and transforming the land: Managing water

6.3 Building settlements, towns, cities and dwellings: Developing urban services and amenities

Construction periods

1866–1977, Enoggera Dam (built 1866; modified 1870, 1887, 1908, 1912, 1931, 1967, 1974 and 1982; spillway added 1976; major modifications 1977)

1866, Valve House

1867, Clerk’s Cottage

1900, Workman’s Cottage

1912, Treatment plant (slow sand filters 1912; dissolved air flotation clarifier 1982)

1930, Pump house (built 1930s)

1972, Memorial Plaque and Tree (dedicated to caretaker 1951-72)

Historical period

1840s–1860s Mid-19th century

Location

Address

30 & 50 Mt Nebo Road, Enoggera Reservoir

LGA

Brisbane City Council

Coordinates

-27.44573736, 152.91647588

Significance

Criterion AThe place is important in demonstrating the evolution or pattern of Queensland’s history.

The Enoggera Dam, constructed in 1866, is part of an early scheme of setting up water supply systems in key towns in Queensland. It is important in demonstrating the pattern of Queensland history following Queensland's separation from New South Wales in 1859 and recognising the need to build substantial water supply infrastructure to service its population and stimulate further growth in the region. The present structures clearly show the change in water storage and treatment technology from the nineteenth to the twentieth century. Only remnants remain of the other dams constructed during this era (Ipswich, Warwick, Maryborough). Enoggera Dam is the only one that remains intact and operational.

Criterion BThe place demonstrates rare, uncommon or endangered aspects of Queensland’s cultural heritage.

The Enoggera Dam is important as the first major dam built in Queensland. It is rare as one of the few remaining examples in Queensland of an intact and functioning reservoir and treatment plant from this period in time.

Criterion DThe place is important in demonstrating the principal characteristics of a particular class of cultural places.

The Enoggera Dam is important in demonstrating the principles characteristics of a nineteenth century water storage facility including an earth embankment across the site to form a reservoir, gradients on the upper and lower sides of the embankment to prevent erosion, treatment plant with slow sand filters from 1912 and outlet works (the pipes used to draw and deliver water) constructed with masonry.

Criterion EThe place is important because of its aesthetic significance.

The Enoggera Dam has aesthetic importance as a collection of visually striking and complementary structures including, the treatment plant, valve house, pump house, storage hut and cottages set against the backdrop of the man-made lake and surrounding bush, which are important scenic elements in this area of the Brisbane Forest Park.

Criterion FThe place is important in demonstrating a high degree of creative or technical achievement at a particular period.

The Enoggera Dam is important in demonstrating a high degree of technical achievement in Queensland as an example of conventional nineteenth century clay cored earthfill dam with a flood mitigation function provided by twentieth century rock fill and concrete technology. The dam also demonstrates an unusual spillway arrangement, which incorporates a flood mitigation function, and an unusual method of drawing water based on using a combination of three outlet pipes to draw and deliver water as opposed to the traditional one or two outlet pipes.

Criterion HThe place has a special association with the life or work of a particular person, group or organisation of importance in Queensland’s history.

The Enoggera Dam has special association with Brisbane's early water supply authorities as it is an example of early major water supply infrastructure as commissioned and operated by the Brisbane Municipal Council, Brisbane Board of Waterworks and the Metropolitan Water and Sewerage Board. It is also associated with renowned engineer, Joseph Brady, one of Australia's earliest and most prominent engineers.

History

The Enoggera Dam is the oldest major dam in Queensland, being commissioned by the Brisbane Municipal Council in 1864 and completed in 1866. It is located on Waterworks Road, The Gap, approximately 10 kilometres west of Brisbane's CBD.

Enoggera Dam was one of the earliest major dams to be built in Australia, the first being the Yan Yean Dam north of Melbourne in 1859. It was a conventional nineteenth century clay cored earthfill dam, designed and built by Joseph Brady.

Prior to the establishment of water supply systems, Queensland residents were expected to make their own arrangements to supply water for themselves. There were a number of different methods used such as collecting rainwater (using the runoff from the roof of a house was popular), sinking a well in their gardens, using water reserves from local creeks or purchasing water from private suppliers.

Since separation from New South Wales in 1859, Queensland's European population grew rapidly, from 23,520 in 1859 to 30,059 in 1861 to over 250,000 by 1883. People were attracted to Queensland by the offers of free passage and gifts of land orders. With such rapid population growth the current methods of water supply were both impractical and inadequate to support and sustain the population. The population growth brought with it an expectation, particularly from immigrants to Queensland, that towns with populations in excess of three to four thousand people should be able to supply residents with a clean, reliable source of water. Prior to the building of Enoggera Dam, Brisbane's main source of water was a small and heavily polluted dam across Wheat Creek [602218], which flowed through the centre of the settlement.

In the early 1860s, Queensland's first governor, Sir George Ferguson Bowen, created municipal councils in the main Queensland towns to provide a foundation upon which the colony's political growth could be based. The municipal councils, realising that strong infrastructure was essential to future growth of the colony, began to investigate the best means of providing a permanent water supply to the Queensland population. Unlike the situation in Britain where private enterprises had traditionally provided infrastructure services such as water supplies, Queensland councils decided from the outset that either the council or publicly run boards would have responsibility of supplying water reticulation systems.

The Brisbane Municipal Council was the first Queensland council to commence proceedings in developing a reticulated water supply. They contracted a civil engineer, Thomas Oldman, to survey Brisbane's water supply in 1863. Oldman recommended schemes based on both the Brisbane River and Enoggera Creek, The Gap, however, the Council preferred Enoggera Creek and this was the option settled on. Another engineer, Joseph Brady, was responsible for the design and construction of Enoggera Dam.

The Gap was originally settled in 1859 by farmers attracted by water in Enoggera Creek and consisted mainly of farming land. The presence of a significant water supply in Enoggera Creek led to it being selected as the site of Brisbane's first major dam and thereby facilitating development in the area.

In 1865, other Queensland municipal councils, Ipswich, Warwick and Maryborough, began surveying water supplies for their areas and after the completion of the Enoggera Dam in 1866, these councils also went on to construct dams.

Construction of Enoggera Dam commenced in 1864 and was completed by 1866. The cost of construction was approximately £65,000, some £15,000 over the council's allocated budget but close to Brady's original estimate of £68,491. After the dam's completion a commemorative drinking fountain, the Walter Hill Fountain, was built in Brisbane Botanic Gardens [600067] to celebrate the arrival of clean drinking water to the city.

In 1867, the Board of Waterworks (later known as Brisbane Board of Water) constructed a cottage on the premises as accommodation for the clerk of the waterworks and later, in 1900, a workman's cottage was also built. Both cottages still exist along Waterworks Road and are still in use as accommodation.

The Enoggera Dam has two unusual features. Its method of drawing water is based on using three outlet pipes as opposed to the traditional one or two outlet pipes. This feature allowed the delivery potential of the dam to be trebled, protected the delivery pipes from damage from the weight of the water and also ensured that in an emergency the water flow could be easily and completely cut off. This arrangement was not in the original designs by Brady and appears to have added at a later date. None of the water supply systems built for the other Queensland councils in the same period appear to have this delivery system. The second unusual feature relates to the spillway, added in 1976. It has a flood mitigation system that incorporates an open culvert at the full water supply level to limit flows in the early part of a flood. This configuration provides an interval during which the peak flood flow from the unregulated downstream catchment can clear before the flood pondage of the reservoir fills and open ogee spillway of the dam begins to function.

The Enoggera Dam demonstrates technological changes over a significant period of time. Since its 19th century construction it has been modified a number of times, particularly after floods in 1870, 1887, 1931, 1967 and 1974. The original outlet work was constructed in masonry, a practice that was discontinued and replaced by concrete shortly after the dam's completion. Modifications were also made in 1908, 1912 and 1982 to improve water quality. Despite the changes, the dam structure remained in near original form until 1977 when major modifications were made to it. This included raising the height, constructing a new byewash and rebuilding the water delivery arrangements. These changes resulted in Enoggera Dam being reopened with a commemorative plaque noting that the new construction incorporated the original 1866 structure.

The Enoggera Dam is no longer the main water supply for Brisbane although it was used to supplement water supplies, albeit in a somewhat modified form, until it was decommissioned in 2003. However, due to prolonged drought conditions, the dam has recently been recommissioned. Of the dams constructed during this period, only Enoggera Dam remains as intact and operational. Only remnants of the dams constructed in Ipswich, Warwick and Maryborough remain. Enoggera Dam now forms part of the scenic Enoggera Reservoir.

Description

The Enoggera Reservoir is located at Waterworks Road, The Gap. It covers an area of 358.1468ha. The Reservoir landscape contains the Enoggera Dam, associated buildings, cleared land and forest. The buildings include, the valve house, treatment plant and underground reservoir, chemical store and office building, two cottages (referred to as eastern cottage and western cottage), pump house, storage hut, toilet block and hut.

Upstream face of the dam embankment, showing the original crest of the dam (with Valve House) and 1970s wall extension.

Enoggera Dam

Enoggera Dam is located on Enoggera Creek, a largely suburban tributary of the Brisbane River which rises at modest elevations in the D'Aguilar Ranges, eleven kilometres north west of the Brisbane CBD.

Valve House

The valve house, built 1866, is a timber-framed, weatherboard clad house that sits on what was once the crest of the original dam but is now at the base of the new dam wall on the upstream side. The valve house controlled the flow at intake from reservoir into the delivery pipes. It no longer functions.

Treatment Plant

The treatment plant is immediately below the dam and comprises a 1982 dissolved air floatation clarifier and slow sand filters dating from 1912. Both systems are still functioning. A brick, flat roofed chemical store and office building stands beside the slow sand filters. Treated water flows to an underground reservoir between the treatment plant and the pump house.

Cottages

The two cottages are accessed from Waterworks Road. Both are timber-framed, high-set iron roofed houses with front verandahs. The eastern cottage is the more ornate. Its gabled portico features decorative barge boards and timber archway through to the verandah. Structural features of both cottages are consistent with early twentieth century dwellings.

Pump House

The pump house is a small, weatherboard hut with a corrugated iron gable roof. It dates from the 1930s. The pump still functions.

Stone Storage Hut

The storage hut is a simple gabled structure built into the slope falling from the treatment plant to the site entry. It has loadbearing stone walls approximately 450mm thick with brickwork quoins or keystones above the second course of stonework. The gable is infilled with weatherboards and the timber-framed roof is clad with corrugated iron.

Toilet Block

The toilet block is a 1960s concrete structure with a flat, metal roof. This structure is not significant.

Concrete Hut

The hut is a 1960s concrete block structure with a flat concrete roof. This structure is not significant.

Memorial Plaque and Tree

Memorial plaque and jacaranda tree (Jacaranda mimosifolia) planted in memory of August Rudolph Sprenger Junior who was the Enoggera Reservoir caretaker from 19 March 1951 until his death on 22 March 1972, aged 57.

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