At one kilometre long the completed bridge is the centrepiece of a two kilometre raised roadway that spans the Mersey estuary between Runcorn and Widnes.

At this point in its journey the river is a shifting patchwork of water courses and tidal mudflats. A place that offers a rich and dynamic environment for wildlife.

With water quality better now than at any time since the industrial revolution it is increasingly important for salmon, sea trout, river lamprey, eels and other fish species. The estuary is also an important nursery refuge for many species of fish.

Tens of thousands of birds meanwhile rely on the estuary’s abundant food stocks, particularly on the extensive mudflats. Its importance for birds, including tens of thousands that overwinter in the area or stop off to refuel during their long winter migrations, has led to international protection.

Marine mammals like dolphins and porpoise are also returning to the estuary in growing numbers.

So before work on the bridge could begin it was vital that studies were carried out to look at how it might affect these sensitive habitats.

Scientists from APEM were brought in to help. A seven year baseline survey was completed and followed by an assessment of potential impacts, plus recommendations for appropriate mitigation measures and further monitoring requirements.

Fish sampling on the Mersey estuary

Between 2002 and 2007 sampling of benthic algae, invertebrates and fish was conducted within the main estuary, as well as of macrophytes and invertebrates within the freshwater watercourses.

APEM director, Dr Adrian Williams, was closely involved with the work over many years and gave expert opinion to the public enquiry into the proposed bridge.

Dr Williams said: “From a scientific point of view the opportunity to work on the Mersey Gateway project was wonderful. APEM and others gathered a wealth of data rarely equalled for a large river estuary in the UK and this gave us a great insight into its functioning and environmental importance.

“Based on this detailed scientific understanding we were able to assure the enquiry and local people that, if properly developed and operated, the bridge’s impact on the environment of the estuary should be very minimal.

“The work was both a privilege and a pleasure and it is fantastic to see the completed bridge open to the public.”

Main photograph: Mersey Gateway New Bridge, by Gerald Murphy, used under CC BY 2.0. Original can be found here.

If you have any queries, please contact Dr Adrian Williams, managing director.
Alternatively you can email us here. Or call 0161 442 8938.