When the Wirral museum was open in Birkenhead Town Hall they displayed a Roman map of Wirral which showed a shipping navigation channel between the Dee and the Mersey. This must have been a canal of some sort which had been dug between them as I don't think there was any natural channel.
If anything it might have been either the River Goey or River Twine? (I googled names but got no hits - any info anyone?)
Are there such rivers now?
The Ellesmere Canal
The easy section from the Mersey to the Dee near Chester, now part of the Shropshire Union Canal, was first used in 1795, and joined to the Chester Canal in
1797.
The Ellesmere Canal was a canal in England and Wales planned to link the Rivers Mersey, Dee, and Severn, but the Ellesmere Canal as originally envisaged was very different from what was eventually constructed.
Part of the Ellesmere Canal has now become known as the Llangollen Canal, part forms part of the Montgomery Canal, and part forms part of what is now called the Shropshire Union Canal main line.
on 1831 map