AN ENORMOUS DAM.

Hawera Star, Volume XLV, 23 December 1925, Page 9

AN ENORMOUS DAM.

SIDNEY'S WATER SUPPLY. WAKE AG AMD A RIVER SCHEME. Ihe slaking of Sydney's tliirst is an ever-recurring problem, owing to tiie rapid growtn of population in tne metropolitan area. Every summer sees restrictions, or threats by the water authority lo place restrictions upon the supply lor gardening, anil even' ordinary household purposes. ’.this consumption of water is continually increasing. In 11)23 the position was serious. .Last- year it was not- so serious, owing •to timely rains, and again this year winter rains, and heavy downpours a few weeks ago have practically assured a bounteous supply lor the coming summer. Put statistics show tnat in these two years the average consumption, due to great growth ’ol factories and residences, has increased by between 15,000,000 and 20.000,000 gallons a day. This figure has caused the Metropolitan Water Board to look a long way ahead, especially as they have the word of the Government statistician that without undue crowding there is room for 4,000,000 people within tlie metropolitan area, and that by 1967, or perhaps sooner, this figure will bo passed. Two immense dams, the Cordeaux and Avon, are nearing completion, and these are expected to safeguard the supply for a decade or two decades lienee. To ensure an adequate supply after that, an even greater dam is now being planned. This is known as the Warragamba scheme, the site being a rocky, precipitous, desolate gorge near Mulgoa, about 50 miles from tlie city, where the Warragamba River enters the Nepean, the latter being the key, stream to the present system of reservoirs.

Surveyors and engineers are now investigating the country and making plans for one of the highest dams in the world, which will gradually take form as the Warragamba, reservoir, assuring Sydney for many years of a plentiful supply of pure water At present the river rushes down the gully and empties its waters into the Nepean, and -thence into the sea. The plan is to divert flood-water through a great ridge to join the river further down, in order to build that enormous dam.

The catchment area for the dam will comprise an area of about 3383 square miles, being oil the southern slope of the famous .Blue Mountains. The area is sparsely populated, there being only about 15° people, to the square mile. After the channel through the ridge has been cut and the dam has been built, the cut channel will be used subsequently as a spillway for flood waters. The scheme is estimated to cost £6.076,000. The total contents of tlie Warragamba dam when filled will Ikj 180,000 million gallons. In flood times the waters of the Warragamba will rush down at, the rate of 420.000 tons a minute.