BBC Wales's Laura Jones: "Creating a fresh water lagoon as the focal point of Cardiff Bay has always been controversial."

The £197m Cardiff Bay Barrage swung into action with the lowering of the sluice gates at high tide on Wednesday night.

The lengthy and controversial scheme will slowly transform the tidal mudflats of the bay into a lake that will become the centrepiece of the massive redevelopment of Cardiff's docklands.

Dredging of the mudflats will take place during the winter to ensure the freshwater lake can be in place by the spring of 2000.

The barrage has meant displacing an important population of wading birds

But the long-awaited Cardiff Bay Barrage has not been without controversy.

Environmental campaigners have condemned the closure of the barrage as "a tragic day for wildlife and a shameful day for New Labour".

Friends of the Earth Cymru (FoE) said the barrage would destroy a nationally important wildlife site to create a £200m "fake lake".

The group have been protesting outside the Assembly condemning the "destruction" of the Taf-Ely estuary.

BBC Wales's Tim Richards: "There are 500 acres of undulating, chocolate mudflats"

"The estuary is a site of special scientific interest visited by thousands of migratory redshank and dunlin which have fed and sheltered there for thousands of years," an FoE spokesman said.

"The barrage will permanently flood the estuary in order to hide the unsightly mudflats creating a lake to encourage waterfront development."

Cardiff West MP Rhodri Morgan was one of the most vociferous campaigners against the project, speaking at a public rally against the scheme at the headquarters of the Cardiff Bay Development Corporation.

The barrage has cost £197m to complete

He is now Assembly secretary for economic development - a crucial role in future decision-making concerning the bay.

The 1km barrage stretches across the waterfront from the docks to Penarth at the confluence of the rivers Taff and Ely.

Once completed Cardiff Bay will feature a number of prestigious buildings, including the £25m Mermaid Quay shopping and leisure complex.