Manly Dam Environment

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Manly Dam

The Manly Dam catchment forms a large valley with an underlying geology of Hawkesbury sandstone. It is rich in plant life with over 300 native plant species, including 18 different native orchids. 

It also provides excellent examples of the typical vegetation communities found on Hawkesbury sandstone in Warringah, such as Sandstone Heath, Silvertop Ash-Brown Stringybark Forest and Duffy's Forest.

The catchment is also home to seven mammals, more than 80 species of birds, 27 species of reptiles and frogs, and three native fish. Animals found at Manly Dam include swamp wallabies, antechinus, brushtailed and ringtail possums, bandicoots, echidnas, blue-tongued lizards, water dragons, monitor lizards, geckos and turtles. 

Environmental Management 

The Manly Dam catchment includes 375ha of bushland plus housing, businesses and sportsfields. If you live in the Manly Dam catchment, water from your property and street drains into Curl Curl Creek and then Manly Dam. By looking after your home and backyard you give your catchment a better chance to remain healthy. 

We manage the catchment and surrounding area to maintain the condition of local bushland and water quality of the dam and local creeks. 

Water quality monitoring began in 1986 and in 1991 a two metre submersible propeller was installed on the dam wall to reduce the severity and frequency of blue-green algae blooms.

Outbreaks of blue green algae are caused by nutrients from stormwater runoff. Nutrients enter the lake from fertilised lawns and gardens, road surfaces, pollution spills, and leachate from old tip sites higher up in the catchment. 

Pollution and algae reduce the water quality and affect swimmers, wildlife and encourage weed growth. 

Our other ongoing programs to help retain the health of the Manly Dam catchment include weed control and bush regeneration, feral animal control programs, fire management planning, installation of sediment traps and trash racks on creeks, enforcement of park by-laws concerning rubbish dumping, auditing of local businesses, and environmental education.

Dogs are not allowed in the water or any of the picnic areas, which includes the internal road and carparks. Dogs may be walked on a leash on bushland walking tracks.

History of the Dam 

Before European settlement, the land between Newcastle and southern Sydney was home to the Guringai people. At Manly Dam you can see evidence of Aboriginal life in the form of rock engravings and painting, shell middens and axe grinding grooves. You may also discover the remains of ancient camp sites such as stone tools, baked clay and fire blackened stones. 

In 1892 Curl Curl Creek was dammed to create Manly Reservoir and provide a permanent supply of fresh water for the village of Manly. As the population grew the dam wall had to be raised. It was first raised in 1909, then in 1922 and finally in 1935.

The Dam's capacity eventually became insufficient and its water supply was phased out. Water started being piped from the Pymble reservoir in 1930. However, a drought that lasted from 1934 to 1942 was so serious that in January 1942 pumps were reinstalled and Manly Dam was brought back into service until October of the same year.

After World War I, Manly Dam was established as a War Memorial Park. In 1939 it was designated as a reserve for public recreation. During World War II the dam was fortified with machine guns and barbed wire. Warringah Council was appointed trustee of the reserve in 1953.