Nepean DamUnique for its Art deco style

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Status Open to Public

Visit the Dam

Nepean Dam was the last and smallest of the four dams constructed to collect water from the Illawarra Plateau south of Sydney. Today, you can walk across the dam wall, and soak up the Art Deco style of construction, which contrasts with the Egyptian influenced architecture of Avon and Cordeaux dams.

 

Lookout points

Dam wall

 

Walk across the dam wall for impressive views of the lake upstream and gorge downstream.

Viewing area above the dam wall

From the lower carpark near the dam wall, walk south along the former construction railway platform now housing log cabin-style picnic shelters to another viewing area of the lake.

Things to do

Large Group notifictaion image and link

Opening hours

Dam Grounds

10am to 5pm daily
Extended hours, 10am to 7pm, on weekends and public holidays during daylight saving time
Entry is free
No entry is permitted 15 minutes prior to closing time

Directions

Nepean Dam is about 100 kilometres drive from Sydney. Follow the Hume Highway (F5) south from Sydney and take the Bargo exit to Nepean Dam.

Facilities

  • Childrens playground
  • Drinking water
  • Electric barbeques
  • Parking
  • Picnic shelters
  • Portable toilet dump point
  • Toilets & disabled toilets
  • Viewing areas
  • Hot Water

Fishing

Restrictions

Restrictions are in place to protect our water supply and ensure that everyone has an enjoyable and safe visit Ė with penalties up to $44,000 applying:

  • No wood, charcoal or solid fuel barbeques. Penalties of up to $5,500 apply
  • Portable gas barbeques are permitted (except during total fire bans)
  • No fishing, boating or swimming
  • No camping
  • No dogs, horses or other pets
  • No access allowed to restricted and Special Areas
  • No smoking within 10 metres of childrenís playgrounds and four metres of shelters, toilets and public buildings
  • Keep to vehicle speed limits and be aware of pedestrians
  •  

Recreation Areas at SCA dams will be closed on ALL Total Fire Ban days.

The Nepean experience

Top 5 things to see and do

1. Walk across the dam wall

To fully appreciate your picturesque surroundings, take a walk across the dam wall. Itís only 216 metres to the other end! Pause halfway and admire the views of the lake upstream. To better imagine how deep the lake is, cross to the other side of the wall and look down. Youíre 82 metres above the ground!

2. Step back in time

Be on the lookout for reminders of the damís past as a favoured picnic spot in the 1930s and 1940s, when dams in the Upper Nepean would compete with each other for who had the most beautiful gardens. Enjoy the mixed plantings of European and native trees in a park-like picnic area along a terrace above the dam, and look out for a long line of Roman Cypress trees that follow the line of the spillway.

3. Soak up the views

Elevated paths and the dam wall provide impressive views of the lake in its natural bushland setting. Nepean Dam draws water from a 320 square kilometre catchment, the largest of the Upper Nepean dams. The Art Deco style of Nepeanís large concrete structures contrasts with the Egyptian style of Avon and Cordeaux dams. Look out for the concrete lined side spillway, which looks like a smaller version of the massive auxiliary spillway at Warragamba Dam.

4. Check out the environmental flows

Variable environmental flows from Nepean Dam and the other Upper Nepean dams mimic natural river flows and help sustain the downstream river environment. Look downstream from the dam wall for the environmental flows that are released all day, every day for the health of the downstream river.

5. Relax with a picnic

Relax with family and friends in the landscaped grounds. Throw down a rug and picnic under a shady tree or use one of our tables or shelter sheds. Electric barbeques, drinking water and toilet facilities are located throughout the grounds. Thereís a childrenís playground at the top picnic ground. Nearer the dam wall, a row of small timber picnic shelters with a log cabin-style feel run along the remnant platform from the temporary railway built during the damís construction.

Facts & History

Located about 100 kilometres south of Sydney, Nepean Dam was the last and smallest of the four dams constructed to collect water from the Illawarra Plateau. Construction started in 1925 but stopped for two years during the Great Depression, before being completed in 1935.

Created by damming the Nepean River, Nepean Damís main role today is to supply water to the nearby towns of Bargo, Thirlmere, Picton and The Oaks, as well as the Macarthur and Prospect water filtration plants.

It also receives water transferred from the Shoalhaven River and Kangaroo River when the Shoalhaven Scheme is in operation to top up our dams.

Together, the Nepean, Avon, Cataract and Cordeaux dams also provide an additional supply of water for Sydney, via Pheasants Nest Weir, Broughtons Pass Weir and the Upper Canal.

Why the dam was built

The Upper Nepean catchment south of Sydney is in one of the highest rainfall zones on the mid-NSW coast, and the areaís rivers, located in narrow gorges, provide ideal dam sites.

As early as 1888, two weirs were built on the Cataract and Nepean rivers to capture this rainfall as part of the Upper Nepean Scheme to help meet Sydneyís growing needs. Tunnels, canals and aqueducts Ė known as the Upper Canal - diverted the water 64 kilometres to Prospect Reservoir.

The scheme provided only temporary relief, and the 1901 - 1902 drought brought Sydney perilously close to a complete water famine. After two Royal Commissions, authorities agreed that a dam be built on Cataract River. The successive building of Cataract, Cordeaux, Avon and Nepean dams between 1907 and 1935 greatly increased the Upper Nepean Schemeís capacity.

How the dam was built

Work on Nepean Dam started in 1925, but was interrupted for a few years by the Depression before resuming in 1933. Materials were hauled on a standard gauge railway line from the main southern line near Bargo. The dam was finally completed in 1935.

Like all Upper Nepean dams, the wall was built using cyclopean masonry Ė sandstone blocks, quarried from the site, fitted into an irregular pattern and packed with sandstone concrete.

Most of the plant and equipment used for the construction of Avon Dam was dismantled and re-erected at the Nepean Dam site, including cableways and timber towers. A suspension bridge was constructed across the Nepean River which was later used at Warragamba Dam.

A township for workers was constructed of timber cleared from the Avon Dam catchment. A typical working man's accommodation consisted of a simple timber hut with a galvanised iron roof. Later, a barracks was constructed for single men. Married men had four and five-roomed cottages. A public school, recreation halls and medical facilities were also provided.

After several years of extremely low rainfall in the catchment, heavy rainfall in October 1938 saw the dam finally reach capacity and overflow via its spillway.

Later improvements

A tunnel linking Avon and Nepean dams, to enable the transfer of water between dams in either direction, was completed in 1973. In 2006 a deep water pumping station was built, allowing water to be transferred to Avon Dam even when the level of Nepean Dam is lower than Avon Dam.

To meet modern dam safety standards, Nepean Dam was strengthened in 1992 by post-tensioned anchors and a downstream rockfill embankment and further safeguarded by a concrete lined side spillway. The full supply level was also reduced by five metres as part of the upgrade.

Dam Summary

82
Metres High
Length: 216 metres
67,730 ml total operating capacity
Size of lake:
3.3 km 2
Catchment: 320 square kilometres

Dam Wall

Size Measurement
Length 216m
Thickness of base m
Width of central spillway m
Concrete mass t
Width of auxillary spillway m
Length of auxillary spillway m

Lake and Catchment

Size Measurement
Area 3.3km2
Length of lake km
Length of foreshores km
Maximum depth of reservoir m
Catchment area 320km2
Annual average rainfall mm

Pipelines

Size Measurement
Diameter mm
Length km each
Capacity ML per day
88.0
Friday 24 October
-0.2
2,271,133 ML
2,581,850 ML
9,878 ML
1,412 ML
-4,095 ML
Friday 24 October
Nepean Dam
Upper Nepean
Friday 24 October
89.7
60,750
67,730
61,103
63,745
60,897
-353
-2,995
-147
90.2
94.1
89.9
-0.5
-4.4
-0.2