A plan to build a barrier across the Mersey is starting to take shape. If it goes ahead, the ambitious project would becomes the largest tidal range facility in the world, while also offering pedestrians and cyclists safe passage across the river.

Plans appear to have been floating around for a while now. Authorities in Liverpool note that first mentions date back as far as 1924, followed by reports and viability studies in the 1980s. Politician John McDonnell recently recalled that he attended his first meeting on a Mersey barrage proposal back in 2015, but things seem to be moving forward at last.

"For as long as I can remember, there has been talk of building a tidal barrage on the Mersey," said Liverpool City Region's mayor, Steve Rotheram, in 2022 as he inked a collaboration deal with South Korean state water company K-Water. "Thanks to devolution – we’re working to make it a reality. There are still huge technical and financial challenges to overcome but Mersey Tidal Power has the potential to provide enough clean, green, predictable energy to power up to one million homes for over a century."

K-Water has been operating the Sihwa Lake Tidal Power Station since 2011, which was installed on a 12.5-km-long (7.76-mile) sea wall originally constructed to mitigate flooding and for irrigation of surrounding farmland. The facility features 10 submerged turbines rated at 25.4 MW each that generate power twice a day at high tide (outflow is sluiced away through gates). This one-way system has an annual production capacity of 552.7 GWh of electricity.

The Liverpool City Region Authority has been working on the technical aspects of several Mersey proposals for around three years (including a man-made lagoon), and Rotheram has now confirmed that the region has selected a bridge/barrage option between Liverpool and the Wirral to go through to the formal planning stage.