An Overview of Our System |
updated: 20/09/07 |
Gosford City and Wyong Shire Councils share a joint water supply scheme. Water is drawn from four streams (Mangrove and Mooney Creeks in Gosford and Wyong River and Ourimbah Creek in Wyong).
There are three operational dams and three operational weirs in the joint water supply (JWS).
The JWS has two water treatment plants, one located at Somersby in Gosford City and the other at Mardi, in Wyong Shire.
Both plants treat raw water and deliver quality water complying with NHMRC/ARMCANZ Australian Drinking Water Guidelines – 1996.
Click here for Map of Catchment area
- The Urban Water Supply System
- Dams
- Weirs
- Water Treatment Plants
- Distribution System
- The Stream System
- Stream Flow Management Strategy
The Urban Water Supply System
Gosford and Wyong Council, through the Authority, manage the third largest urban water supply system in New South Wales.
Early infrastructure was built seventy-five years ago, but most infrastructure in use today was built during the past twenty years.
The water supply headworks dams, weirs, treatment plants and associated works are jointly owned and operated by the two Councils. Water is drawn from Mooney Dam and weir pools on Wyong River, Mangrove Creek and Ourimbah Creek.
During dry periods water can be released from Mangrove Creek Dam to provide sufficient inflow at the weirs on Mangrove Creek and Wyong River.
Wyong River and Ourimbah Creek extractions are stored in Mardi Dam.
Dams
The Authority has three operational dams:
Storage
Built
Height (m)
Construction
Capacity (ML)
Mangrove Creek Dam
1980
82
Concrete Face Rock Fill
190,000
Mardi Dam
1962
26
Earth Fill
7,400
Mooney Dam
1961
28
Concrete Arch
4,600
Mangrove Creek Dam (MCD) is located on Mangrove Creek some 28km upstream from its junction with the Hawkesbury River. Its direct catchment is 101 sq km. Mangrove Creek Dam water is not used routinely.
The purpose of the dam is to store water until it is needed. The need arises when stream flows are low and hence Mardi Dam and Mooney Dam are drawn down to the extent that satisfactory raw water for treatment is not available.
At those times, water is released from the dam to boost stream flows in Mangrove Cree and/or Wyong River.
Mooney Dam is located in Mooney Mooney Creek some 21 km from its junction with the Hawkesbury River. Its contributing catchment is 39 sq km. Water from the dam is pumped to Somersby Water Treatment Plant.
Mardi Dam is an off creek storage located 4km south-west of Wyong. It is fed by water pumped from Wyong River and Ourimbah Creek, respectively located 2km and 5km from the dam.
Its contributing catchment is only 2 sq km. Water from the dam is transferred to Mardi Water Treatment Plant.
Weirs
The Authority has three operational weirs:
Storage
Height (m)
Construction
Weir Pool (ML)
Mangrove Creek
3.0
Concrete/Steel
100
Wyong River
<1.0
Concrete/Rock
300
Ourimbah Creek
4.0
Concrete
45
Mangrove Creek Weir residual catchment is 140 sq km (excludes catchment above Mangrove Dam). Inflow to the weir may be supplemented by waters released from Mangrove Creek Dam.
The pumping station, located adjacent to the weir, pumps raw water 14 km to Somersby Water Treatment Plant.
Wyong River Weir has a large catchment of 355 sq km. Inflow to the weir may be supplemented by waters released from Mangrove Creek Dam via the Boomerang Creek Tunnel.
The pumping station locate upstream of the weir, pumps raw water to Mardi Dam.
Ourimbah Creek Weir has a catchment of 88 sq km. A pumping station located close to the weir pumps 5.6 km to Mardi Dam.
Water Treatment Plants
The Authority’s two water treatment plants are located at Somersby in Gosford City and Mardi in Wyong Shire. Both plants treat raw water and product water complying with NHMRC/ARMCANZ Australian Drinking Water Guidelines – 1996.
Somersby Water Treatment Plant was constructed in two stages, the first in 1971 with subsequent augmentation in 1986 providing a maximum production rate of 140ML per day. The plant’s treatment processes are:
Flocculation and primary sedimentation
Sand and anthracite filtration; and
Disinfection
Mardi Water Treatment Plant was constructed in two stages, the first in 1984 with subsequent augmentation in 1992 providing a maximum production rate of 160ML per day.Treatment processes are the same as at Somersby Water Treatment Plant except there is no primary sedimentation. Mardi Dam satisfies the purpose of primary sedimentation.
Distribution System
Gosford and Wyong Councils manage all aspects of the distribution system within their local government area. This includes meter reading, finance and accounting, network design, system operation and maintenance.
The Authority is involved where water is transferred between the two councils. This occurs with the Bateau Bay/Foresters Beach/Wamberal link and inland where the link is from Kariong through to Ourimbah to Tuggerah 2 Reservoir.
The system has been designed to enable water to be transferred in both directions if necessary.
Trunk mains and pumping stations deliver water through the distribution system to the 40 storage reservoirs. The reservoirs serve to maintain stable water pressure, supplement water availability during high demand periods and provide a safety net - should a failure occur within the distribution system.
Consumers are supplied from the network of smaller diameter pipes connected to reservoir outlet mains and trunk mains.
The Stream System
Mangrove Creek, Mooney Mooney Creek, Ourimbah Creek and Wyong River provide the source water for the Central Coast’s urban water supply.
The Authority endeavours to ensure catchment sustainability and manages the water supply headworks infrastructure.
Stream Flow Management Strategy
Gosford/Wyong Councils’ Water Authority as a water user is committed to supporting the NSW Government’s water reform process.
The Authority’s Stream Flow Management Strategy is based upon an Expert Panel’s recommendations for the management of possible environmental impacts water supply activities may have on contributing streams.
Key function of the Authority:
- Strategic planning to ensure safe, affordable water is always available.
- Strategic management of assets and catchment.
- Representing the Councils on Joint Water supply issues.
- Audit the Joint Water Supply operation for standards and management compliance.
Input to Councils’ planning to bring a regional perspective to water supply and sewerage issues.
Click
here for Map of Catchment area