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Water History Case Study

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Where would you have put the dam?
The current Central Coast Water Supply System
Historical development of the Water Supply System
Timeline of development of the Central Coast Water Supply

NOT HERE, PLEASE Dam construction is almost always a controversial and emotive issue. As a means of ensuring urban water supplies, the building of a dam to capture and store surface runoff from a catchment is nearly always cheaper than other options such as desalination of sea water or recycling treated wastewater. On the other hand, building a dam locks up the catchment, preventing many other forms of land use for the indefinite future. Furthermore, a dam has a wide range of environmental impacts (some good, some bad) on the catchment, both above and below the wall. Unless, as rarely happens, the dam is intended to occupy an uninhabited locality, the decision to build is often at the expense of existing land holders and their ways of life. These issues apply not only to dam-building but to the provision of the whole gamut of infrastructure – water treatment plants, reservoirs, pipelines etc concerned with providing clean water supplies for human populations. CASE STUDY In this Case Study we will explore the decision-making processes involved in the provision of water supply. We will use the history of the development of the water supply on the Central Coast, particularly the construction of the Mangrove Creek dam, as an example of the research, planning, and political debate required to decide between competing priorities in the supply of this most precious of our resources – clean, fresh, H2O.

What is the structure of the current Central Coast water supply system? Gosford City and Wyong Shire Councils share a joint water supply scheme administered by the Gosford/Wyong Council’s Water Authority. This is the third largest water supply system in NSW. Water is drawn from four streams (Mangrove and Mooney Creeks in Gosford and Wyong River and Ourimbah Creek in Wyong). The building of water storage infrastructure was begun 75 years ago, but most infrastructure used today was completed during the past thirty years. Currently, the system incorporates three dams, three weirs, two treatment plants, 40 reservoirs, and 1900 km of pipelines. It has a total catchment area of about 10,000 hectares or 100 square kilometres. Water is drawn from Mooney Dam and weir pools on Wyong River, Mangrove Creek and Ourimbah Creek. Wyong River and Ourimbah Creek extractions are stored in Mardi Dam. During dry periods, when the Coastal Mooney and Mardi Dams cannot meet the demand for water, supply can be released from Mangrove Creek Dam to provide adequate inflows at the weirs on Mangrove Creek and Wyong River. Before being delivered to the community the “raw” water is treated to produce a water quality that complies with the high standards of the NHMRC/ARMCANZ Australian Drinking Water Guidelines – 1996. The JWSS has two water treatment plants, one located at Somersby in Gosford City and the other at Mardi, in Wyong Shire. (Gosford Wyong Councils’ Water Authority) Figure 1: The Current Central Coast Water Supply System (Gosford Wyong Councils’ Water Authority) QUESTION: Think about the water that flows so freely from our tap and that so often we take for granted. What do you think are the most important general issues that Water Authorities over the years have had to consider in providing our houses with piped water? List four of these.

Plate 4: Aboriginal grinding grooves in a tributary of Bucketty Gully. Attenbrow (2004) in ‘Terra Australis’ 21. For thousands of years, Aboriginal people on the Central Coast relied on the fresh water resources of natural rivers, creeks and water holes within the Gosford Wyong region. Europeans moving into the area two centuries ago tended to build their settlements close to those same natural water supply points. As settlement expanded out from these surface water sources, they were supplemented with water from dug wells and household tanks. It wasn’t until 1929/1930 that the first centralised water supply system was implemented for the town of Wyong. A concrete-lined reservoir was constructed on Chapman Hill and water was pumped to it from the Wyong River for distribution to the residents. In 1938, town water came to Gosford, when the Mayor turned on the new water supply direct from a dam on the lower reaches of Mooney Mooney Creek. Piping water to the northern areas of the Wyong Shire began in the 1950s. In 1960, the first stage of the Entrance Water Supply Scheme commenced. Officially opened in 1965, the expanded scheme eventually provided reticulated water throughout much of the Shire. A new dam on Mooney Mooney Creek (4600 ML) was built in 1961 to replace the old one further down the creek. A year later Mardi Dam (7400 ML) and Wyong River Weir were completed. A weir across lower Mangrove Creek was built in 1975. As dependence on these centralised facilities increased, it became more and more important that the raw water from them be treated to guarantee standards of public health. In line with this, Somersby Water Treatment Plant was constructed, the first stage in 1971 and a subsequent stage in 1986, resulting in a maximum production rate of 140 megalitres per day. In Wyong Shire, the first stage of the Mardi Water Treatment Works was opened for use in 1984 with subsequent augmentation in 1992 providing a maximum production rate of 160 ML per day. These developments in infrastructure were matched by improvements in management of the system. In 1977 Gosford and Wyong Councils entered into an agreement (the Gosford and Wyong Council Joint Water Supply Agreement) to construct, operate, maintain, and share costs of the water supply headworks. This agreement was administered by the Gosford/Wyong Joint Water Supply Committee. Under this agreement Councils and NSW Department of Public Works completed construction of a major storage dam on Mangrove Creek in 1982. This dam was an eighty feet high, rock-filled wall with a storage capacity of 190,000 ML. Provision was made to increase the height by 25 meters to a total capacity of 420,000 ML if the need arose. In 1989 an 11km tunnel linking Mangrove Creek Dam and Wyong River was completed. This tunnel enables transfers of water from the dam to Wyong River for later extraction at the Wyong River pumping station and weir (for pumping to Mardi Dam storage). Over the next two decades, this Joint Committee evolved into the Gosford/Wyong Councils’ Water Authority with an independent Chairman overseeing the management of the Joint Water Supply Scheme (JWSS). Since 1992 a severe drought has impacted the Central Coast. This has required implementation of a comprehensive drought management strategy by Councils. One outcome has been WaterPlan 2050 - a detailed program to expand supply and reduce per capita demand to ensure future needs are met.

Construct a timeline of the events outlined on the previous page using the Table below. The table below carries a list of dates in the left hand column. The right hand column contains a set of images with their matching descriptions, but the order of the events has been scrambled. Try to match the events to the listed dates. (You may like to use the template in Appendix 2, and paste photocopies of the events in the appropriate blank cells of the Table.) Date Scrambled historical events in the development of the water supply 1930 First stage of the Mardi Water Treatment Plant constructed. (The second stage was completed in 1994.) 1961 Construction of the large Mangrove Creek storage dam completed. This dam stores 190,000 megalitres and is the main Central Coast water storage. Seven years later an 11km tunnel linked Mangrove Creek Dam to Wyong River .The tunnel enables transfers of water from the dam to Wyong River for later extraction at the Wyong River pumping station and weir (for pumping to Mardi Dam storage). 1962 The Entrance Water Supply System completed. 1965 Wyong and Gosford Councils adopted the WaterPlan 2050 strategy designed to ensure adequate water supplies on the Central Coast for the next 50 years. A key part of this strategy is the Mardi to Mangrove Dam Pipeline which will be completed by 2010. Other parts of this strategy will be constructed progressively over the next 50 years. 1971 Water pumped from Wyong River to a small reservoir on Chapman Hill for delivery to Wyong residents through a network of pipelines. 1982 Upper Mooney Mooney dam was completed. This dam replaced the Lower Mooney Mooney Dam which had been constructed in 1937. 1982 & 1989 First stage of the Somersby Water Treatment Plant constructed. 2007 Completion of Mardi Dam and Wyong River Pumping Station and associated weir. (Images: Wyong Council) OPEN-ENDED QUESTION: Over the years, Central Coast residents have often heard opinions expressed that Mangrove Creek Dam was an unnecessary expense or that it was built in the wrong place. Examine the information in Appendix 1 and see if you can identify the contribution that Mangrove Creek dam makes to the provision of a safe clean water supply on the Central Coast.

This case study of the history of water supply on the Central Coast of NSW

Where would you have put the dam?
The current Central Coast Water Supply System
Historical development of the Water Supply System
Timeline of development of the Central Coast Water Supply

This case study of the history of water supply on the Central Coast of NSW asks the question: 'Where would you have put the dam?'. It was written to address those curriculum areas in the Geography Syllabus for years 11-12 that focus upon the management of water resources and land-use planning. This case study of the history of water supply on the Central Coast of NSW asks the question: 'Where would you have put the dam?'. It was written to address those curriculum areas in the Geography Syllabus for years 11-12 that focus upon the management of water resources and land-use planning.

Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.

The standard chunk of Lorem Ipsum used since the 1500s is reproduced below for those interested. Sections 1.10.32 and 1.10.33 from "de Finibus Bonorum et Malorum" by Cicero are also reproduced in their exact original form, accompanied by English versions from the 1914 translation by H. Rackham.

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