Nepean River
Encyclopedia
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
The headwaters of the Nepean River rise near Robertson
Robertson, New South Wales
Robertson is a small town in the Southern Highlands of New South Wales, Australia, in Wingecarribee Shire. The town is located on the edge of an elevated plateau about 35 km from the coast. At the 2006 census, Robertson had a population of 1,206 people.Robertson is known for its high annual...
, about 100 kilometres south of Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
and about 15 kilometres from the coast. The river flows north in an unpopulated water catchment area into Nepean Dam, which supplies water for Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
. North of the dam, the river forms the western edge of the Sydney Basin, flowing past the towns of Camden
Camden, New South Wales
-Education:Camden is the location of research facilities for the veterinary and agricultural schools of the University of Sydney. The local government area has two public high schools, Camden High School and Elderslie High School, as well as eight Catholic and three Anglican schools.-Culture:The...
and Penrith
Penrith, New South Wales
Penrith is a suburb in western Sydney, in the state of New South Wales, Australia. Penrith is located west of the Sydney central business district and is the administrative centre for the local government area of the City of Penrith...
, south of which flowing through the Nepean Gorge
Nepean Gorge
The Nepean Gorge is a gorge on the Hawkesbury-Nepean River west of Sydney, New South Wales. It is south of the western suburb of Penrith. It is carved through the sandstone typical of the region, Hawkesbury sandstone...
. Near Penrith it is joined by the Warragamba River
Warragamba River
The Warragamba River is a tributary of the Nepean River, and hence of the Hawkesbury River, in New South Wales, Australia. It is best known for being the location of the Warragamba Dam and Lake Burragorang, which form a major part of the water supply to the Sydney region.Prior to the creation of...
. North of Penrith, at the junction of the Grose River
Grose River
The Grose Valley is a rugged valley in the Blue Mountains, New South Wales, Australia. It has been formed by the Grose River, the headwaters of which are in the Mount Victoria area...
near Yarramundi, the Nepean becomes the Hawkesbury River
Hawkesbury River
The Hawkesbury River, also known as Deerubbun, is one of the major rivers of the coastal region of New South Wales, Australia. The Hawkesbury River and its tributaries virtually encircle the metropolitan region of Sydney.-Geography:-Course:...
.
There are 11 weirs located on the Nepean River that significantly regulate its natural flow. The river has been segmented into a series of ‘weir lakes' rather than a freely flowing river and is also impacted by dams in the Upper Nepean catchment.
The Wallacia Weir was initially built as a wooden weir for the John Blaxland
John Blaxland
John Blaxland was a pioneer settler and explorer in Australia.-Early life:Blaxland was born in Kent, the eldest son of John Blaxland and Mary, née Parker, of Fordwich, Kent, England. He was the older brother of Gregory Blaxland. John Blaxland was educated at The King's School, Canterbury, later...
flour mill at Grove Farm. The first Australian fishsteps were built when the current concrete weir was built at the beginning of the Nepean Gorge
Nepean Gorge
The Nepean Gorge is a gorge on the Hawkesbury-Nepean River west of Sydney, New South Wales. It is south of the western suburb of Penrith. It is carved through the sandstone typical of the region, Hawkesbury sandstone...
, an anticendant entrenched meander caused by the slow uplift during the Blue Mountains orogeny
Orogeny
Orogeny refers to forces and events leading to a severe structural deformation of the Earth's crust due to the engagement of tectonic plates. Response to such engagement results in the formation of long tracts of highly deformed rock called orogens or orogenic belts...
carved down through the Hawkesbury sandstone ~50Mya.
In the 1950s the building of the Warragamba Dam
Warragamba Dam
Warragamba Dam is the primary water source for the Australian city of Sydney. It is approximately to the west of Sydney on the Warragamba River, a tributary of the Hawkesbury River, and impounds Lake Burragorang.- Overview :...
across the steep gorge of the Warragamba River, the Nepean’s major tributary, intercepted the flow of the great bulk of its waters and diverted them to meet the needs of the growing Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
metropolitan area, reducing the river to a shadow of its former self.
These dams and weirs have had a potent effect, blocking migratory native fish like Australian bass
Australian bass
Australian bass are a small to medium sized, primarily freshwater native fish found in coastal rivers and streams along the east coast of Australia. They are a member of the Percichthyidae family and, currently, the Macquaria genus. Australian bass are an iconic, highly predatory native fish...
(also locally commonly known as perch) from much of their former habitat, and reducing floods and freshets needed for spawning. Nevertheless, the Hawkesbury/Nepean remains an important and popular wild bass fishery.
The luscious banks of the Nepean River provide a natural haven for local flora and fauna and a quiet location for local residents to relax. At Emu Plains, the western bank of the river provides a location for outdoor theatre productions on warm summer nights. The eastern bank at Penrith provides barbecue
Barbecue
Barbecue or barbeque , used chiefly in the United States, Canada, the United Kingdom, New Zealand and Australia is a method and apparatus for cooking meat, poultry and occasionally fish with the heat and hot smoke of a fire, smoking wood, or hot coals of...
facilities and children's play equipment, as well as a wide pathway running for several kilometres for strolls along the riverbank. The eastern bank is also the home of the Nepean Rowing Club.
History: European Settlement
When the BritishKingdom of Great Britain
The former Kingdom of Great Britain, sometimes described as the 'United Kingdom of Great Britain', That the Two Kingdoms of Scotland and England, shall upon the 1st May next ensuing the date hereof, and forever after, be United into One Kingdom by the Name of GREAT BRITAIN. was a sovereign...
colony was established at Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
in 1788, the Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
men in charge of the settlement went exploring by boat. They discovered the mouth of the Hawkesbury River
Hawkesbury River
The Hawkesbury River, also known as Deerubbun, is one of the major rivers of the coastal region of New South Wales, Australia. The Hawkesbury River and its tributaries virtually encircle the metropolitan region of Sydney.-Geography:-Course:...
about 50 kilometers north of Port Jackson
Port Jackson
Port Jackson, containing Sydney Harbour, is the natural harbour of Sydney, Australia. It is known for its beauty, and in particular, as the location of the Sydney Opera House and Sydney Harbour Bridge...
(Sydney Harbour) and followed the river upstream, naming it after Charles Jenkinson, 1st Earl of Liverpool
Charles Jenkinson, 1st Earl of Liverpool
Charles Jenkinson, 1st Earl of Liverpool PC , known as the Lord Hawkesbury between 1786 and 1796, was a British statesman. He was the father of Prime Minister Robert Jenkinson, 2nd Earl of Liverpool....
, who at that time was titled Baron Hawkesbury.
Meanwhile, Watkin Tench
Watkin Tench
Lieutenant-General Watkin Tench was a British Marine officer who is best known for publishing two books describing his experiences in the First Fleet, which established the first settlement in Australia in 1788...
of the Royal Marines
Royal Marines
The Corps of Her Majesty's Royal Marines, commonly just referred to as the Royal Marines , are the marine corps and amphibious infantry of the United Kingdom and, along with the Royal Navy and Royal Fleet Auxiliary, form the Naval Service...
set off to walk inland, west of Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
. About 60 kilometers inland, at the foot of the Blue Mountains, he discovered a large river which he named Nepean after a different British politician
Politician
A politician, political leader, or political figure is an individual who is involved in influencing public policy and decision making...
, Evan Nepean
Evan Nepean
Sir Evan Nepean, 1st Baronet PC was a British politician and colonial administrator.-Early career:...
. It took the Navy and the Army about three years to realise they had discovered the same river and given it two different names.
During the 1820s, the Nepean district's most famous early settler, the landowner and physician Sir John Jamison
John Jamison
Sir John Jamison was an important Australian physician, pastoralist, banker, politician, constitutional reformer and public figure....
(1776-1844), erected a magnificent Georgian house on the model estate which he had established on a rise overlooking the river, not far from the present-day City of Penrith
City of Penrith
The City of Penrith is a Local Government Area in Sydney, located about west of Sydney's central business district.- History :The Municipality of Penrith was incorporated on 12 May 1871 under the Municipalities Act 1858. On 3 March 1890, St Marys was separately incorporated, and on 26 July 1893...
. Sadly, Regentville House burned down in the 1860s but Sir John's reputation remains as one of early Australia's most important political and agricultural pioneers.
Floods in the Nepean District
Early floodsThe first flood on record - apparently a small occurrence - was in 1795. Others followed in 1799, 1806 and 1809. In 1810, after a series of major floods on the Hawkesbury, Governor Macquarie proclaimed the ‘Macquarie Towns’ of Windsor, Richmond, Wilberforce, Castlereagh and Pitt Town in an attempt to ensure that development was restricted to higher ground, free of flooding. The devastation caused by flooding in February, 1817 prompted Governor Macquarie to issue a notice exhorting settlers, in the strongest possible terms, to build their residences above the established flood levels.
The most devastating flood occurred in June 1867, the Nepean River being estimated to have reached a height of about 13.4 metres in the river, and 27.47 metres on land, ie 27.74 metres AHD (Australian Height Datum). This flood carried away the approaches to the recently rebuilt Victoria Bridge
Victoria Bridge (Penrith)
Victoria Bridge, also known as the Nepean River Bridge, is a wrought iron girder bridge which crosses the Nepean River in the western suburb of Penrith in Sydney, Australia...
. Emu Plains, Castlereagh and the lower parts of Penrith
Penrith, New South Wales
Penrith is a suburb in western Sydney, in the state of New South Wales, Australia. Penrith is located west of the Sydney central business district and is the administrative centre for the local government area of the City of Penrith...
were all under flood, causing immense loss of property. Many houses were carried into the river by landslides. Many residents were forced to take refuge in public buildings such as the Penrith Hospital and the public schools. A major flood such as that of 1867 caused inundation of over 16,000 dwellings and damage costing in the order of $1.4 billion.
There have been other notable floods since, particularly that of July 1900 and March 1914. Again there was much flooding of streets and loss of houses and property along the river.
1974 was another significant La Niña
La Niña
La Niña is a coupled ocean-atmosphere phenomenon that is the counterpart of El Niño as part of the broader El Niño-Southern Oscillation climate pattern. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 3–5 °C...
flood event.