Lake Medlow Dam

Lake Medlow Dam

Located about 110 kilometres west of Sydney, Lake Medlow Dam is on Adams Creek, between Katoomba and Blackheath.

Believed to be one of the thinnest dam walls in the world (only 106 centimetres wide at the top), the dam is located between Katoomba and Blackheath. It was the first of the dams built as part of the development of the upper Blue Mountains.

Today it still supplies water to the middle and upper Blue Mountains. The dam is not open to the public.


Height: 20 m
Length: 38 metres

Total storage capacity: 326 ML

Lake: 5 ha
Catchment: 5 square kilometres

Lake Medlow Dam history

Originally known as Adams Creek Dam, Lake Medlow Dam was built in 1907 on Adams Creek. It was the first of the water supply dams built as part of the development of the Upper Blue Mountains.

It was the first concrete thin arch, high stress dam built in NSW. Only 274 centimetres wide at the bottom and 106 centimetres at the top, it is one of the thinnest dams in the world and created considerable controversy when it was completed.

The Institution of Engineers, Australia placed a historic engineering marker on the dam in 1994. The National Trust and Blue Mountains City Council have registered the dam on their heritage list.

The completion of Lake Medlow Dam was a significant step in providing a reliable water supply for Medlow Bath, Blackheath and surrounding areas. Today, the dam supplies water via the Cascade dams to the Cascade water filtration plant, which provides water to the middle and upper Blue Mountains.


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