How Cardiff turned a polluted bay into one of Europe’s best waterfronts

Rivers in the Welsh capital once ran black with coal dust. Now, they form a clean lake that has become the revitalized heart of the city. (Matthew Dixon/Shutterstock)

CARDIFF, Wales — This city’s bayfront is often packed with people: families boarding tour boats, office workers enjoying a waterside lunch, theatergoers out strolling before a performance, and fans of the TV show Doctor Who emerging from tours of the BBC studios where the series is made.

It wasn’t always this way.

Just 30 years ago, Cardiff Bay was dead — both environmentally and economically. For decades, the two rivers that feed into the bay — the Taff and the Ely — had been so black with coal dust, sewage and industrial waste that no fish could survive. Nearby mines that once exported one-third of the world’s coal through Cardiff’s port had shut down. So had steel factories, put out of business by cheaper foreign competition. Cardiff, whose center lies a mile inland, turned its back on the decrepit port and befouled bay.

But over time, the Welsh capital has gone to great lengths to clean up both its water and its waterfront. Tourists and locals alike now swarm the dockside known as Mermaid Quay, while salmon once again swim in the bay and run up the rivers to spawn. Cardiff Bay is no longer seen as an embarrassment. Rather, it’s an amenity to paddle on, eat by and live near — a new locus for residential, commercial and retail development for a growing city-region of 1.4 million people.

During its heyday, Cardiff’s port exported one-third of the world’s coal. (Ernest T. Bush)

How that transformation happened is an instructive story for any city struggling with polluted waterways. It’s also a reminder of how urban regeneration over the long run requires public and private forces to come together around a common goal.

Making a lake

Some of Cardiff’s inspiration came from across the Atlantic in the U. S. city of Baltimore. Around the same time plans to clean up Cardiff Bay were hatching, Baltimore was cleaning its own polluted bay and creating a “festival marketplace” of shops and offices on the waterfront. A group headed by the UK Secretary of State for Business returned from a visit impressed with what they saw.

In 1987, the UK Government created the Cardiff Bay Development Corporation under the chairmanship of Sir Geoffrey Inkin, who had served on the council of a nearby county. He was backed by an 11-person board with members from local administrations, academia and the private sector; Michael Boyce, the chairman of Cardiff City, served as CEO. The Secretary of State for Wales tasked the Corporation with upgrading infrastructure and implementing a development strategy, with a mandate to engage the private sector.

The infrastructure needs were huge. For example, the Corporation spent £14 million (roughly US$34 million in today’s dollars) on diverting sewage that used to outfall directly in the bay. The water company Hyder built a new sewage treatment plant at a cost of £118 million ($US283 million today).

But the biggest project — and the real key to the area’s revival — was out at the mouth of Cardiff Bay where its waters meet the sea. This is where the Corporation built a great dam, known as Cardiff Bay Barrage. Opened in 1999, the 1.1-kilometer (half-mile) barrage essentially seals off the freshwater bay from the saltwater sea. Before, large tides left vast mudflats exposed twice a day, stranding any boats in the smelly muck. The barrage created a permanent lake that became quite clean as environmental standards were raised and enforced. 

The Cardiff Bay Barrage (left) created a freshwater lake that has become home to much waterfront development. (Cardiff Harbour Authority)

The barrage includes a long rock and sandfill embankment, rising to a maximum height of 20 meters (66 feet). It contains three locks to admit vessels and five sluices to control the water level inside and keep most of the seawater out. Two fish passes allow salmon and trout to migrate between the sea and the rivers. Atop the dam, hundreds of people daily use a walk-and-cycle path that connects Cardiff to a suburb called Penarth.

The barrage also improves Cardiff’s defenses against flooding and sea-level rise. “If a lot of rain is forecast, we drop the bay to allow the water to come in,” says David Hall, an environmental officer with the Cardiff Harbour Authority, which operates the barrage. When I spoke with Hall recently, water in the bay was at 4.5 meters, or about 15 feet. “But everything in the bay is designed to be allowed to rise another four meters above that level,” he says, “to take account of high astronomical tides and a 1-in-100 year storm event at the same time.”

Strict standards

When it was built, Cardiff Barrage was opposed by environmentalists, who saw it as a threat to birds who fed at the exposed tidal mudflats. The opposition was overcome partly by creating a much larger bird reserve further east along the coast. Looking at the bay now, with its clean waters supporting healthy populations of salmon and trout, it’s hard to recall the controversies that once dogged the project.

To clean up the bay, the strictest environmental standards were applied — and still are. Diverting raw sewage to be treated before reaching the bay helped a lot in this regard. So did a UK law that set specific requirements around oxygen levels in the waters, a move intended to help fish and their prey. About 12 km (7 miles) of specially laid underwater pipes regularly pump compressed air into the water through more than 100 diffusers.

The Cardiff Bay Barrage keeps saltwater out and freshwater in  and allows trout and salmon to pass through. (David Thorpe)

Monitoring sites located around the lagoon continuously check water quality in the bay, measuring temperature, pH, turbidity, conductivity and salinity. This data is pushed out on the over the web in real time. Fish monitoring also has been installed, using sophisticated technology that can identify species by their silhouettes and estimate their numbers using algorithms.

“The spawning potential of the River Taff — for trout and salmon — is now very, very good,” says Hall. Bird species and numbers are also monitored, according to David Evans, a colleague of Hall’s at the Harbour Authority. “They have recorded over 150 species, including egrets, in the bay.”

Building by the bay

While the infrastructure and water cleanup work was going on, so was a lot of real estate development.

Tim Levenson, who worked for the Cardiff Bay Development Corporation for ten years and became its senior environment manager, recalls that the Corporation “had to get the momentum going from scratch.” Rotting  warehouses needed to be demolished in order to make the land suitable for development.

“The Corporation took commercial advice on who might be attracted to the area and what densities of development might be achieved and how the plots should be divided up,” Levenson says. “We then did a lot of marketing, persuading investors to buy up land and showing a vision of what it would be like.”

You would think that it might be necessary to give financial incentives to developers to come to what was then a physically and environmentally unattractive location. But very few sweeteners were given. “We thought putting in the infrastructure — primarily the barrage, buying land and crating development sites — and creating the vision was sufficient,” says Levenson. He notes that the Corporation also made and guided other investments to make the area desirable, such as cleaning up contaminated land, adding motorways including a tunnel, building a visitor center, planting trees and commissioning public art.

Mermaid Quay is a popular place to eat, go for a stroll or catch a boat ride in Cardiff Bay. (David Thorpe)

Among the early big names coming to the bay was NCM Credit Insurance company, which moved into a flashy new office building with a roof resembling a sail. As the first to build on the waterfront, NCM did receive a £2.5 million grant from the Cardiff Bay Development Corporation. The Rocco Forte chain of luxury hotels followed with the glistening white tower of the St Davids Hotel.

Another unusual aspect of the process for a project of this kind was that it was not managed by the city council. “We had to work very closely and get on well with them,” Levenson says. “Bearing in mind, we were not the local planning authority. We were given protocols and mechanisms to resolve any potential conflicts, should they arise, but most of the planning applications we put in were passed — only a few minor ones were not. But then, we were a conduit for government funding.”

The Corporation had targets to aim for in terms of securing private investment, creating jobs and redeveloping the area. These goals were set by the central government in London in a special Act of Parliament in 1993, and by The Welsh Office. By 2000, most of these targets had been met. The Corporation was dissolved. Its development powers were handed back to the local council, while the Cardiff Harbour Authority was created to take care of the bay.

The barrage completes a heavily used walking and cycling path that connects Cardiff to its southern suburbs. (David Thorpe)

The Harbour Authority’s Hall puts the total cost of the bay cleanup at £2 billion. That includes about £600 million in public money, of which £220 million was used for the barrage. The rest was private finance.

Projects continue to arrive, including an 800-home waterfront community in the pipeline. It’s part of an International Sports Village that boasts an Olympic-size swimming pool, ice rink and whitewater kayaking center. These join marquee public buildings such as the Welsh National Assembly, a glass box designed by architect Richard Rogers, and the Wales Millennium Centre, a theater and concert hall with a bold copper portico.  Altogether, Cardiff now has one of the most attractive and cosmopolitan waterfronts in Europe.

Cardiff’s transformation isn’t complete. Levenson notes that a rail link and a key road link remain unfinished. But it’s a far cry from the scenes of polluted desolation that gripped this place a generation ago, or the hard-drinking “rough dockers” that worked the port here generations before that.

“There’s a lot more that can be done in terms of leisure and tourist attractions, and more residential accommodation,” Levenson says. “It’s not finished yet, but I am very proud of what has happened.”

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David Thorpe is a journalist, consultant, workshop leader and speaker in the fields of carbon-free energy, energy efficiency and sustainability.   Full bio


  • The UK government appointed a development corporation to regenerate Cardiff’s decrepit docklands.
  • The corporation built a barrage that essentially turns Cardiff Bay into a freshwater lake that has become a locus for new development.
  • Enforcement of strict water standards has cleaned up pollution in the bay and returned trout and salmon to its waters.

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