Mangrove Creek Dam, a concrete faced rockfill embankment dam, is the primary reservoir for water supply to residents of the Central Coast in New South Wales, Australia. The dam, with a capacity of and fed by a catchment area of , is operated by the Central Coast Water Corporation and supplies approximately 93 per cent of water to residents in Central Coast Council. The dam was constructed between 1978 and 1982, formed by impounding the headwaters of Mangrove Creek, a tributary of the Hawkesbury River. Dam and spillway statistics The concrete faced rockfill embankment dam was built due to a rising demand for water from the expanding population on the Central Coast. The dam was built to boost water supply storage and to help provide a more reliable water supply. Mangrove Creek Dam was built using rolled, soft rockfill of sandstones and siltstones. This material was obtained from a quarry located within the storage area. These sandstones and siltstones were crushed and compacted to form the dam embankment. The embankment also contains approximately of processed basalt. This material was incorporated into various filters and drains within the embankment to cope with seepage within the embankment and foundations. The concrete face which tapers from at the base to at the crest acts as a seal between the water and the dam embankment. Provision was made to increase the height of the dam wall by to a total capacity of if the need arose in the future. The height of the dam wall is , with a length of . The dam spillway is a concrete lined chute of approximately with a width that tapers from to , with the capacity to discharge a water flow of into the impounded Mangrove Creek. During 1989, the Boomerang Creek Tunnel was completed. This tunnel enabled water to be transferred from Mangrove Creek Dam to Wyong River, for extraction at the Wyong River Weir for storage in Mardi Dam. This water was then extracted downstream at Lower Wyong River Weir and pumped for storage in Mardi Dam. Catchment Mangrove Creek Dam was proposed as a large storage dam, not primarily a collection dam. Its catchment area was relatively small but the shape of the valley and its geology enabled the construction of a relatively high wall that would store of water, reaching a maximum water depth in the reservoir of . When at full supply,