Lake Burley Griffin

2007 Schools Wikipedia Selection. Related subjects: Geography of Oceania (Australasia)

Lake Burley Griffin is a lake in the centre of Canberra, Australia's federal capital city. It was created in 1963 after the Molonglo River, which runs through the city centre, was dammed. It is named after Walter Burley Griffin, the architect who won the design competition for the city of Canberra.

The lake is located in the approximate geographic centre of the city, according to Griffin's original designs. Numerous important institutions, such as the National Gallery of Australia, National Museum of Australia, National Library of Australia and the High Court of Australia lie on its shores, and Parliament House is a short distance away. Its surrounds are also quite popular with recreational users, particularly in the warmer months. Though swimming in the lake is uncommon, it is used for a wide variety of other activities, such as rowing, fishing, and sailing.

The lake's flow is regulated by the 33 metre tall Scrivener Dam, which is designed to handle a once in 5000 year flood event. If required in times of drought, water levels can be maintained through the release of water from Googong Dam, located on an upstream tributary of the Molonglo River.

Design

Charles Robert Scrivener (1855-1923) recommended the site for Canberra in 1909, and his detailed survey plans of the area were supplied to the architects who entered the Canberra design competition. Later, Scrivener, as part of a design committee, was responsible for modifying Griffin's winning design. He recommended changing the shape of the lake from Griffin's very geometric shapes to a much more organic one using a single dam, unlike Griffin's series of weirs. The new design included elements from several of the best design submissions and was widely criticised as being ugly. The new plan for the lake retained Griffin's three formal basins: east, central, and west, though in a more relaxed form. The plans were varied again in the following years with the return of Griffin, but the design of Lake Burley Griffin remains based largely on the original committee's plan.

The lake contains 33 million m³ of water with a surface area of 6.64 km² (2.56 sq mi). It is 11 kilometres (7 mi) long, 1.2 kilometres (0.75 mi) wide at its widest point, has a shoreline of 40.5 kilometres (25.2 mi) and a water level of 556 metres (1824 feet) above sea level. Lake Burley Griffin contains six islands, three unnamed small islands and three larger named islands. Of the larger islands, Aspen Island is located in Central Basin while Springbank and Spinnaker Island are located in the West Basin. Aspen Island is connected to dry land by a footbridge and is the site of the Australian National Carillon.

Construction

Excavation

Construction of Lake Burley Griffin was begun in 1960 and progressed well due to drought having greatly reduced the water flow of the Molonglo River. Critics believed that the lake would act as a breeding ground for mosquitoes. Care was taken to excavate the lake to a depth of over two metres both to prevent mosquitoes from breeding and to allow clearance for boat keels. The lake varies in depth from around 2 metres at the eastern end, to 18 metres at the dam wall. The mean depth is 4 metres.

Dam

The dam used to create Lake Burley Griffin was named Scrivener Dam after Charles Robert Scrivener. The dam is 33 metres high and 319 metres long with a five bay spillway controlled by 30.5 metre wide, hydraulically operated fish-belly flap gates. The fish-belly gates allow for a precise control of water level, reducing the dead area on the banks between high and low water levels. The five gates have only been opened simultaneously once in the dam's history, during flooding in 1976. The dam is designed to handle a once in 5000 year flood event. The dam contains 55,000 cubic metres of concrete with a maximum wall thickness of 19.7 metres. A roadway atop the dam wall provides a third road crossing for the lake.

Filling

The drought that had made construction easy meant that when the valves were closed on 20 September 1963 the lake was very slow to fill. After seven months there was still only a trickle of water and some mosquito-infested pools. Luckily the drought broke and the lake was filled after only several days of heavy rain.

On October 17, 1964 Robert Menzies commemorated the filling of the lake and the completion of stage one with an opening ceremony. The minister for the Interior, Gordon Freeth suggested that Menzies had "been in a material sense the father of the lake" and that the lake should be named Lake Menzies. Menzies insisted that the lake should be named after Walter Burley Griffin—Canberra's designer responsible for the concept of the lake—who had no existing monument in Canberra. (Griffin usually referred to himself as Walter Griffin, but the form "Walter Burley Griffin" has become established in Australia.)

Lake levels in times of severe drought can sometimes fall below the desired level. This can be compensated for by the release of water from Googong Dam on the Queanbeyan River, a tributary of the Molonglo. Googong Dam was built in 1979 to cope with Canberra and Queanbeyan's growing water supply needs, and can contain up to 124,500 million litres of water.

Bridges

Lake Burley Griffin is crossed by Commonwealth Avenue Bridge (310 metres), Kings Avenue Bridge (270 metres) and a roadway over Scrivener Dam. The two bridges were constructed before the lake was filled and are designed to allow the passage of recreational sailing boats with tall masts. Both bridges are dual-carriageway, Commonwealth Avenue has three lanes in each direction while Kings Avenue has two.

Site testing for both the Commonwealth Avenue Bridge and the Kings Avenue Bridge took place during late 1959 to early 1960.

Scrivener Dam is crossed by Lady Denman Drive which has a narrow two lane roadway.

Captain Cook Memorial

The Captain James Cook Memorial was built by the Commonwealth Government to commemorate the Bicentenary of Captain James Cook's first sighting of the east coast of Australia. The memorial includes a water jet located in the central basin and a skeleton globe sculpture at Regatta Point showing the paths of Cook's expeditions. On 25 April 1970, Queen Elizabeth II officially inaugurated the memorial.

The water jet is powered by two 560 kilowatt electric motors driving four stage centrifugal pumps capable of pumping up to 250 litres per second against a head of 183 meters. The water velocity at the water nozzle is 260 km/h. While running both pumps simultaneously the main jet throws approximately six tons of water into the air at any instant, reaching a maximum height of 147 metres. Alternatively the jet can be run on a single pump reaching a lower height of 110 metres. During special occasions it can be illuminated, often with coloured lights.

The water jet operates from 10-11.45 a.m. in the morning and 2-3.45 p.m. in the afternoon. During summer it also operates for an extra period from 7-9 p.m.. In periods of high wind the jet is automatically disabled as water landing on the nearby Commonwealth Avenue Bridge can be a hazard to traffic. The water jet must also be occasionally shut down when drought lowers the water level of the lake.

Water quality

Toxic blue-green algae blooms are unfortunately a reasonably common occurrence in the lake. Warnings about coming into contact with the water are released when an algal bloom is detected. Attempts are being made to limit the amount of phosphates entering the lake in the hope of improving its water quality. Blue-green algae (more correctly cyanobacteria) produce toxins, which can be harmful for humans and any other animals that come in contact with the contaminated water. There have been several cases of dogs being affected after playing in and drinking the lake water.

The water also appears murky due to a high level of turbidity, possibly a result of the bottom feeding of large numbers of introduced carp in the lake.

Lakeside recreation

The surrounds of Lake Burley Griffin are very popular recreational areas, especially in the warmer months. Public parks exist for most of the shore line with free electric barbecue facilities, fenced-in swimming areas, picnic tables and toilet facilities. Some of the parks reserved for public recreation include Commonwealth, Weston, Kings and Grevillea Parks, Lennox Gardens and Commonwealth Place. A bike path also surrounds the lake with riding, walking or jogging around the lake being a popular activity on the weekends. Fireworks are often held over the lake on New Years Eve, and there has been an annual large fireworks show called Skyfire run at the lake since 1988.

Water sports

Lake Burley Griffin, apart from being ornamental, is used for many recreational activities. Sailing and windsurfing are popular all year round. A rowing course is set up at the western end of the lake. Swimming is becoming less common due partly to concerns about water quality and generally cold water temperature. During summer, the lake is used for the swim leg of numerous triathlon and aquathlon events including the Sri Chinmoy Triathlon Festival.

Generally powerboat use on the lake is not permitted. Permits are available for the use of powered boats on the lake for use in rescue, training, commercial purposes or special interest (historic steam powered boats, etc). Molonglo Reach, an area of the Molonglo River just before it enters the east basin is set aside for water skiing. Powerboats may be used in this limited area.

Fishing

Fishing is quite popular in the lake with the most common species being the illegally introduced Carp. The lake has been stocked annually with a variety of introduced and native species and over 1.26 million fish have been released since 1964. Annual monitoring is carried out to determine fish populations. The 2001 survey only returned Carp and Redfin perch, both introduced species, and native Golden Perch. However a number of less common species also inhabit the lake, including native Murray Cod, Western Carp Gudgeon and Silver Perch, as well as introduced Goldfish, Gambusia, Rainbow trout and Brown trout.

There have been many changes to the fish populations in the lake as well as stocking practices since it was first filled. Stockings of introduced Trout have been abandoned as the lake has proved to be a warm, eutrophic habitat that is not suited to the survival of introduced Trout species.

Regular stocking since the start of the 1980s have re-established reasonable populations of Golden Perch and highly elusive Murray Cod; native fish that were indigenous to the Molonglo River before the lake was built, but had been lost to mining pollution of the Molonglo River in the 1930s and 1940s. Today Golden Perch and Murray Cod are the only fish stocked in the lake. Murray Cod are remarkable as freshwater fish for the extreme sizes they achieve and this is particularly the case for Lake Burley-Griffin; specimens to approximately 38 kg have been recorded and there is no doubt there are a few even larger Murray cod in the lake.

Safety

The lake is patrolled by the Australian Federal Police water police. The water police give assistance to lake users, helping to right boats and towing crippled craft to shore.

At most swimming locations around Lake Burley Griffin there are fenced-in swimming areas for safety. In the more popular areas, there are also safety lockers with life belts and emergency phones for requesting help. Between 1962 and 1991 seven people died from drowning in Lake Burley Griffin.

For reasons of safety and water quality the lake is zoned for different activities in separate sections. The zoning for each section is as follows:

• Molonglo Reach, the Molonglo River from Dairy Road to East Basin Pavilion is zoned for primary contact water activities such as swimming and water skiing.
• East Basin, from Molonglo Reach to Kings Avenue Bridge is zoned for Secondary contact water sports only (sailing or rowing). This part of the lake is shallow and tends to have higher turbidity picked up from the lake bottom in windy conditions. The shore of the lake in this area is walled to discourage swimming.
• Central Basin between Kings Avenue and Commonwealth Avenue is also zoned a secondary contact area and is edged with walls.
• West Lake and Tarcoola Reach, the area of the lake from Commonwealth Avenue to Kurrajong Point is the primary recreational area of the lake. Primary as well as secondary contact water sports are allowed. Beaches, boat ramps and jetties encourage lake use in this area.
• Yarramundi Reach, situated just before Scrivener Dam has a marked rowing course. It is zoned for secondary contact but primary contact activities are also allowed.

Panoramic images

Notable lakeside places

East Basin

• Kingston Foreshores Development
• Kingston Powerhouse

Central Basin

• Commonwealth Park
• Commonwealth Place
• High Court of Australia
• National Carillon
• National Gallery of Australia
• National Library of Australia
• National Science and Technology Centre
• Regatta Point

West Basin

• Albert Hall
• Hotel Canberra
• Lennox Gardens
• National Museum of Australia

West Lake

• Black Mountain Peninsula
• Government House
• Weston Park
• Yarralumla Yacht Club