Samu Huttunen, the lead hydrologist advising Porto on the Ribeira da Vela stream, quit at a public hearing on Friday, hours after his team published findings that challenge the city’s showcase restoration project. He said he could no longer endorse the market’s description of its indoor watercourse as a revived natural stream.
The study found that only 430 metres (1,410 feet) of the stream had been opened to the air beside and inside Mercado da Vela, a renovated produce hall in the Bonfim district. A further 670 metres (2,200 feet) of the project’s advertised 1.1-kilometre route (0.68 mile) remains in a sealed pipe, researchers say.
What the water tests found
The market reopened in February, with a shallow channel running between tiled walkways and food stalls. The city’s renewal office presented it as the centrepiece of a plan to bring a buried urban stream back into public view, and said the €34 million cost included habitat work, flood controls and the market’s renovation.
Huttunen’s team took samples over 12 weeks from May to August, comparing water at the stream’s upper entry point with samples inside the market. Their paper says 57% of the flow at the indoor channel came from treated reclaimed water, while the water warmed from an average 18.1°C (64.6°F) upstream to 25°C (77°F) near the market exit.
They sold a water feature as a living river, and I can no longer sign my name beneath that claim.
Samu Huttunen, hydrologist
Huttunen said the results did not show that the water was unsafe for shoppers, but argued that the project’s public claims overstated its ecological gains. He also accused the renewal office of excluding his team from a final review of the channel’s design. The office denies that account and says the study measures one summer’s conditions, not the project’s long-term performance.
Traders reject the ‘fake river’ label
Ava Wilson-Richards, the office’s project manager, said reclaimed water was added to maintain a visible flow during dry months and was disclosed in the project’s technical plan. “This is a working urban stream, not a museum exhibit,” she said, adding that engineers had kept the buried section in place because opening it would have required major excavation beneath streets and buildings.
For traders, the argument has turned a striking feature into an awkward selling point. Myrtle Grimes, who runs a fruit stall facing the channel, said customers had asked whether the water was “just decoration”. She welcomed the cooler, open space but said the dispute had damaged the market’s reputation before the first full summer trading season.
Calls for a second examination
Rudolf Krieger, an ecologist who reviewed the published data, said the temperature rise deserved urgent attention because warm water can hold less oxygen and place pressure on aquatic life. But he cautioned that the study did not establish whether the reclaimed-water share was harmful, and called for year-round sampling, including checks on insects and fish at both ends of the route.
The city has asked a separate laboratory to repeat the water tests and says it will publish the results by 15 December. Wilson-Richards said the channel would remain open during the review; Huttunen, who has returned his advisory badge, said he would not take part. Porto’s environmental committee is due to decide next month whether to suspend the project’s application for a European urban-design prize.
