Launcestonians had an opportunity to watch the creation of a major enterprise on our doorstep when the Trevallyn dam and power station were built in the 1950s.

This project replaced the Duck Reach scheme, which was the first public hydro plant in the Southern Hemisphere.

Duck Reach was still serviceable, but only produced two megawatts.

The new scheme ultimately generated 102 megawatts.

The impetus came from the proposed aluminium smelter at Bell Bay.

At first, Premier Cosgrove said the Trevallyn scheme would be cancelled if the plant didn't go ahead.

That caveat soon changed, as domestic demand rapidly grew.

The location for a power station wasn't an issue, but the dam site saw conflicting interests, with upstream farmers concerned about being flooded out, while the Hydro needed a good fall to maximise efficiency.

The debate was often confused by people misunderstanding the locations of Duck Reach and the Second and Third Basins.

Duck Reach, for example, is the site of the 1890s dam, not the power station.

The site chosen was below Third Basin, and would flood it, plus an area up past Reedy Basin as far as Hadspen.

Diamond drilling commenced in 1948 to gain an understanding of the geology.

Labour shortages of the time would be met by migrants and transfer of men from the Butler's Gorge project.

By late the 1940s contracts had been awarded to a French company for construction of the tunnel, and British and Swedish companies for the power station.

Preliminary blasting work for the east end of the tunnel was already underway, shaking many homes around Pomona Road.

The Hydro had to settle some claims for damage.

The dam was the Hydro's part of the project, with the first concrete pour achieved in November 1952, after a coffer dam had been built above the site to control river flows.

That year also saw complaints from migrants about the food they were given at the huge single-men's camp.

A separate village for workers (named Marrawaylee) was located at the end of Pomona Road.

Sadly, an engineer living there fell from the dam wall and drowned in 1953. He was Vernon ("Jimmy") Wright from Sidmouth.

Jubilant French miners cheered on April 23, 1954 as they broke through to create a 3.2-kilometre tunnel (6.5 metres wide) from the dam to the power station, while at Trevallyn the scaffolding for construction of the power station began to go up.

The tunnel dropped 130 metres vertically and ran underground except for a 100-metre section at Pitt Avenue, where it was exposed by a valley.

The whole development was commissioned in 1956 - a credit to the workers, contractors and Hydro.

It's nice to know that in any future crisis, the development could supply Launceston's domestic power and water needs.