# Trevallyn Dam

> Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Trevallyn_Dam
> Markdown URL: https://mediated.wiki/source/Trevallyn_Dam.md
> Source: https://en.wikipedia.org/wiki/Trevallyn_Dam
> Source revision: 1352581161
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)

Dam and hydroelectric power station in Tasmania

Dam in Northern Midlands, Tasmania

Trevallyn Dam Trevallyn Dam in 2009 Interactive map of Trevallyn Dam Country Australia Location Launceston, Northern Midlands, Tasmania Coordinates 41°26′52″S 147°5′11″E / 41.44778°S 147.08639°E / -41.44778; 147.08639 Purpose Power Status Operational Opening date 1955 (1955) Operator Hydro Tasmania Dam and spillways Type of dam Gravity dam Impounds South Esk River Height 33 m (108 ft) Length 177 m (581 ft) Dam volume 61×10^3 m3 (2.2×10^6 cu ft) Spillways 1 Spillway type Uncontrolled Spillway capacity 8,500 m3/s (300,000 cu ft/s) Reservoir Creates Lake Trevallyn Total capacity 12,330 ML (10,000 acre⋅ft) Catchment area 8,986 km2 (3,470 sq mi) Surface area 148 ha (370 acres) Maximum width 390 m (1,280 ft) Normal elevation 124 m (407 ft) AHD Trevallyn Power Station Coordinates 41°25′12″S 147°06′36″E / 41.42000°S 147.11000°E / -41.42000; 147.11000 Operator Hydro Tasmania Commission date 1955 (1955) Type Run-of-the-river Hydraulic head 130 m (430 ft) Turbines 2 x 20.9 MW (28,000 hp) 2 x 27 MW (36,000 hp) (all English Electric Francis-type) Installed capacity 95.8 MW (128,500 hp) Capacity factor 0.8 Annual generation 492 GWh (1,770 TJ) Website hydro.com.au [1][2]

The **Trevallyn Dam** is a [gravity dam](/source/Gravity_dam) across the [South Esk River](/source/South_Esk_River) in [Launceston](/source/Launceston%2C_Tasmania), [Tasmania](/source/Tasmania), Australia. Completed in 1955, the resultant [reservoir](/source/Reservoir), Lake Trevallyn, was established for the purpose of generating [hydroelectricity](/source/Hydroelectricity) within the northern [Midlands](/source/Midlands_(Tasmania)) and [West Tamar](/source/West_Tamar) region. The **Trevallyn Power Station** is a [run-of-the-river](/source/Run-of-the-river_hydroelectricity) [hydroelectric](/source/Hydroelectric) [power station](/source/Power_station), owned and operated by [Hydro Tasmania](/source/Hydro_Tasmania).

## Dam and reservoir overview

The Trevallyn Dam is a concrete gravity dam built on [dolerite](/source/Dolerite) bedrock. The dam wall is 33 metres (108 ft) high and is 177 metres (581 ft) long. When full, Lake Trevallyn has a storage capacity of 12,330 [megalitres](/source/Megalitre) (10,000 [acre⋅ft](/source/Acre-foot)) and covers a surface area of 148 hectares (370 acres), drawn from a [catchment area](/source/Drainage_basin) of 8,986 square kilometres (3,470 sq mi). The [spillway](/source/Spillway) is 26.8 metres (88 ft) high.[2] The reservoir also receives water from [Great Lake](/source/Great_Lake_(Tasmania)) via the [Poatina Power Station](/source/Poatina_Power_Station).[1][3]

### Reservoir

Lake Trevallyn is the long, narrow lake created by the dam and extends as far as [Hadspen](/source/Hadspen%2C_Tasmania) where the first rapids begin at the junction of the [Meander](/source/Meander_River_(Tasmania)) and South Esk rivers. The widest point on the lake is at Stephenson's Bay where it reaches 390 metres (1,280 ft) wide.

Launceston's outer suburb of [Blackstone Heights](/source/Blackstone_Heights%2C_Tasmania) and part of the Trevallyn State Recreation Area form part of the shore of Lake Trevallyn. Land around the lake is a mixture of suburbs, agricultural land and dry [eucalypt](/source/Eucalypt) forest.

#### Facilities

The lake and some of the surrounding land is used as a recreation area. Most facilities are located at Aquatic Point which include a boat launching ramp, jetty and ski-jump.[4] A walking track connects Aquatic Point to the dam wall and Trevallyn State Recreation Area. The dam wall features a viewing platform, parkland and barbecue facilities. Most areas of the lake are open to boating and fishing with the exception of waters near the dam and penstock intake.

#### Algal blooms

Lake Trevallyn is often prone to algal blooms in the warm summer months. The blooms are due to high nutrient levels from sewerage treatment and fertilizers, limited water movement and warm temperatures. The main species is [Anabaena circinalis](/source/Anabaena_circinalis) and though it has the potential to be toxic, no blooms recorded in the lake have proven to be toxic to date. Since 2007, a monitoring program has been in place to keep a check on algal levels and to notify authorities when blooms occur.[5]

#### Jellyfish

In 2009, scientists discovered the freshwater jellyfish, [Craspedacusta sowerbyi](/source/Craspedacusta_sowerbyi), in the waters of Lake Trevallyn close to Blackstone Heights. Believed to have been brought by migrating birds from [China](/source/China), the jellyfish were accidentally discovered during routine water testing. The jellyfish are non-venomous and translucent with average sizes around 2 centimetres (0.79 in) across. Though introduced, the jellyfish are believed to have a beneficial impact on the area as they consume the larvae of mosquitoes. A few specimens were temporarily displayed at the [QVMAG](/source/Queen_Victoria_Museum_and_Art_Gallery) in [Launceston](/source/Launceston%2C_Tasmania) after the discovery was made.[6][7]

## Hydroelectric power station

Trevallyn Power Station, c. 1970

Part of the Great Lake and South Esk scheme that comprises three hydroelectric power stations, the Trevallyn Power Station is the final station and is located adjacent to the [Tamar River](/source/Tamar_River_(Tasmania)), north of Launceston, making use of daily flows down the South Esk River.

The dam diverts water through a 3.3-kilometre-long (2.1 mi) [penstock pipeline](/source/Penstock) to the power station.[2] Water flows underground for its entirety except for a short, 100-metre-long (330 ft) portion that leaves the ground near Pitt Avenue due to a valley intersecting the tunnel's course. The pipeline splits underground into four smaller pipes immediately before entering the station's turbines. The water enters the penstock tunnel 130 metres (430 ft) above sea level and leaves the power station at sea level, entering the Tamar River via the Tailrace Bay on Tie-Tree Bend.

The Trevallyn and Poatina power stations are the only hydroelectric power stations located in the drainage basin of the South Esk River. The tunnel through which the pipeline runs is cut through dolerite and was excavated by a French tunnelling company. The bay that the used water is discharged into was excavated using mostly steam driven equipment and tram ways with the two tailing mounds now forming the Tailrace Park (south side) and the Tailrace Convention Center (north side). The Tailrace Bay has been adapted to serve recreational purposed and also provides a safe anchorage for yachts.[8]

The power station was commissioned in 1955 by the [Hydro Electric Corporation (TAS)](/source/Hydro_Tasmania) and replaced the [Duck Reach Power Station](/source/Duck_Reach_Power_Station). The station has two 20.9-megawatt (28,000 hp) [English Electric](/source/English_Electric) [Francis-type](/source/Francis_turbine) [turbines](/source/Water_turbine) and two 27-megawatt (36,000 hp) English Electric Francis-type turbines, with a combined generating capacity of 95.8 megawatts (128,500 hp) of electricity.[8][9] Within the station building, each turbine has a fully embedded spiral casing. A main inlet valve is located in the station immediately upstream of each turbine for maintenance and security purposes. No. 1 and no. 2 machines are equipped with a turbine relief (bypass) valve to reduce pressure rise in the turbine and penstock during rapid guide vane closure. The station output, estimated to be 492 [gigawatt-hours](/source/Kilowatt-hour) (1,770 [TJ](/source/Terajoule)) annually,[1] is fed to [TasNetworks](/source/TasNetworks)' transmission grid via two three-phase [Alstom](/source/Alstom) generator transformers and two 3-phase English Electric generator transformers to the outdoor switchyard.[9]

Water is discharged into the Tamar River at sea level by an open tailrace channel.

The construction village, named Marrawaylee, is now part of the suburb of West Riverside and is accessed by Pomona Road. The power station and the open land for the transmission lines now serve as a border between the Launceston suburbs of Riverside and Trevallyn.

## See also

- [Australia portal](https://en.wikipedia.org/wiki/Portal:Australia)
- [Water portal](https://en.wikipedia.org/wiki/Portal:Water)
- [Renewable energy portal](https://en.wikipedia.org/wiki/Portal:Renewable_energy)

- [List of power stations in Tasmania](/source/List_of_power_stations_in_Tasmania)

- [List of reservoirs and dams in Tasmania](/source/List_of_reservoirs_and_dams_in_Australia#Tasmania)

- [List of run-of-the-river hydroelectric power stations](/source/List_of_run-of-the-river_hydroelectric_power_stations)

## References

1. ^ [***a***](#cite_ref-ancold_1-0) [***b***](#cite_ref-ancold_1-1) [***c***](#cite_ref-ancold_1-2) ["Register of Large Dams in Australia"](https://web.archive.org/web/20131212120804/http://www.ancold.org.au/wp-content/uploads/2012/10/Dams-Australia-2010-v1-for-website.xls). *[Australian National Committee on Large Dams](/source/Australian_National_Committee_on_Large_Dams)*. 2010. Archived from [the original](http://www.ancold.org.au/wp-content/uploads/2012/10/Dams-Australia-2010-v1-for-website.xls) ([Excel](/source/MS_Excel) (requires download)) on 12 December 2013. Retrieved 23 June 2015.

1. ^ [***a***](#cite_ref-report_2-0) [***b***](#cite_ref-report_2-1) [***c***](#cite_ref-report_2-2) ["Environmental review document for the South Esk-Great Lake Hydro Catchment"](https://web.archive.org/web/20110911220858/http://www.cathedralrocks.com.au/documents/Our%20Environment/SEGL%20Environmental%20Review.pdf) (PDF). *Hydro Tasmania*. pp. 16–17. Archived from [the original](http://www.cathedralrocks.com.au/documents/Our%20Environment/SEGL%20Environmental%20Review.pdf) (PDF) on 11 September 2011.

1. **[^](#cite_ref-3)** Cole, B. (ed.). *Dam Technology in Australia 1850-1999*. [ANCOLD](/source/ANCOLD).

1. **[^](#cite_ref-4)** ["Facilities - Trevallyn Dam Boat Ramp"](http://www.mast.tas.gov.au/domino/mast/facweb.nsf/v-web-facilities-area/40AD42C7392F48EECA256B2800318277?OpenDocument&Menu=Marine%20Facilities). *MAST.tas.gov.au*.

1. **[^](#cite_ref-5)** ["Lake Trevallyn Algal Bloom Monitoring Program"](http://www.nrmnorth.org.au/-projects/lake-trevallyn-algal-bloom). *NRM North*.

1. **[^](#cite_ref-6)** ["Scientists Discover Jellyfish in Lake Trevallyn"](http://www.abc.net.au/news/2009-03-18/scientists-discover-jellyfish-in-lake-trevallyn/1623284). *[ABC News](/source/ABC_News_(Australia))*. Australia. 18 March 2009.

1. **[^](#cite_ref-7)** ["Jellyfish a cure for mozzies Weird News"](http://www.themercury.com.au/article/2009/03/19/62135_fun-weird-news.html). *[The Mercury](/source/The_Mercury_(Hobart))*. 19 March 2009.

1. ^ [***a***](#cite_ref-hydro_8-0) [***b***](#cite_ref-hydro_8-1) ["Trevallyn Power Station | Our power stations: Great Lake - South Esk"](http://www.hydro.com.au/energy/our-power-stations/great-lake-south-esk). *[Hydro Tasmania](/source/Hydro_Tasmania)*. 2015. Retrieved 7 July 2015.

1. ^ [***a***](#cite_ref-hydrotech_9-0) [***b***](#cite_ref-hydrotech_9-1) ["Trevallyn Power Station Fact Sheet: Technical fact sheet | Energy: Our power stations"](https://web.archive.org/web/20120324104540/http://www.hydro.com.au/system/files/attachments/Trevallyn_Power_Station-Fact-Sheets.pdf) (PDF). *[Hydro Tasmania](/source/Hydro_Tasmania)*. Archived from [the original](http://www.hydro.com.au/system/files/attachments/Trevallyn_Power_Station-Fact-Sheets.pdf) (PDF) on 24 March 2012. Retrieved 7 July 2015.

## External links

Wikimedia Commons has media related to [Trevallyn Dam](https://commons.wikimedia.org/wiki/Category:Trevallyn_Dam).

- ["Trevallyn Power Development"](http://www.hydro.com.au/home/Energy/Tasmanian+Hydro+Electric+Schemes/Catchment+Areas/Great+Lake+and+South+Esk+Catchment/Trevallyn+Power+Development.htm). *[Hydro Tasmania](/source/Hydro_Tasmania)*.

v t e Dams and reservoirs in Tasmania, Australia Central Highlands Arthurs Lake Catagunya Clark Cluny Lake Binney Lake Echo Liapootah Meadowbank Miena Pine Tier Repulse Wayatinah King Island Upper Grassy North East Briseis Cascade Clarence Curries River Duck Reach Weir Frome Monarch Mount Paris North West Guide River Henty Pet River White Spur Northern Augusta Cethana Devils Gate Ford Mackenzie Meander Paloona Parangana Rowallan Taylor No. 3 Trevally Wilmot South Craigbourne Flagstaff Gully Hall No. 2 Knights Creek Limekiln Gully Lower Reservoir Ridgeway Rileys Creek Risdon Brook Stanton South West Edgar Gordon Laughing Jack Scotts Peak Serpentine Western Anthony and levee Bastyan and levee Crotty Darwin Mackintosh Tullabardine Margaret Murchison Newton Reece Decommissioned Tolosa Park Category | List

v t e Lakes and other bodies of water in Tasmania, Australia Coastal lagoons and lakes Bronte Dulverton Jocks Orielton Little Waterhouse Freshwater Beatrice Dora Flannigan Meston St Clair Flooded Arthurs Brady Chain Binney Bradys Bronte Dee Echo Pine Tier Tungatinah Great King William Pedder Edgar Glacial Dove Selina Westwood Salt Fidler (Meromictic) Man-made reservoirs Barrington Burbury Catagunya Cethana Craigbourne Gairdner Gordon Henty Huntsman Liapootah Mackenzie Mackintosh Margaret Meadowbank Murchison Paloona Parangana Pieman Plimsoll Repulse Rowallan Rosebery Trevallyn Wayatinah Lakes portal

v t e Launceston landmarks Buildings and structures Boag's Brewery Church of the Apostles Country Club Casino Duck Reach Power Station Launceston Gasworks Holyman House Hotel Grand Chancellor King's Bridge St Andrew's Kirk St John's Church Launceston Synagogue Trevallyn Dam Institutions Albert Hall Launceston General Hospital Launceston Town Hall Entertainment Inveresk & York Park Precinct Majestic Theatre National Theatre Princess Theatre Star Theatre Tasmania Zoo Galleries and museums Entally House Franklin House Queen Victoria Museum & Art Gallery Sports Launceston Aquatic NTCA Ground Elphin Sports Centre The Silverdome Symmons Plains Raceway University of Tasmania Stadium Transport Launceston Airport Metro Victoria Bridge, Launceston Nature and parks Cataract Gorge City Park

v t e Energy in Tasmania Hydroelectric Derwent Butlers Gorge Catagunya Cluny Lake Echo Liapootah Meadowbank Nieterana Repulse Tarraleah Tungatinah Wayatinah Gordon-Pedder Gordon Franklin Dam controversy Mersey-Forth Cethana Devils Gate Fisher Lemonthyme Paloona Parangana Rowallan Wilmot West Coast King John Butters Lake Margaret Pieman / Anthony Bastyan Mackintosh Reece Tribute Yingina / Great Lake Poatina Tods Corner Trevallyn Others Huntsman Decommissioned Duck Reach Moorina Waddamana Waddamana B Wind farms Granville Harbour Musselroe Woolnorth Cattle Hill Huxley Hill (King Island) Natural gas Tamar Valley Decommissioned Bell Bay Organisations Alinta Aurora Powerco Hydro Tasmania Roaring 40s TasNetworks Former Transend Networks Interconnectors Basslink Planned Marinus Link Other Office of the Tasmanian Economic Regulator 2016 Tasmanian energy crisis List of power stations in Tasmania

---
Adapted from the Wikipedia article [Trevallyn Dam](https://en.wikipedia.org/wiki/Trevallyn_Dam) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Trevallyn_Dam?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.