Country diary: Lost and found at Sheffield station – a section of the River Sheaf | Ed Douglas

The ground under my feet starts vibrating, so I look up and see a London train rumbling into view. Two crows, also disturbed, lift themselves off a signalling mast to settle again on a high wall dotted with buddleia. A few gulls are squabbling overhead against a greying sky that has left Platform 5A slick with drizzle. Then I lower my head again to the mesmerising square of water rushing beneath my feet.

It is the first view of the River Sheaf at this spot since the late 1860s, when it was culverted and plunged into darkness for the construction of Sheffield station, right where another stream, the Porter Brook, flows into it. Now, like some Roman mosaic or Anglo-Saxon hoard, a fragment of this treasure has been exposed, with the opening of a lightwell, protected by a steel grille, that allows rail passengers to look down on the lost river that gave their city its name.

This excavation is the work of the Sheaf and Porter Rivers Trust, which aims “to bring the Sheaf back into Sheffield”, but there’s more to it than a simple patch of light falling on the rippling water, this window on a city’s soul. Rivers are nature’s arteries, even here, deep in the urban jungle, and to thrive they need not just clean water, but sunshine too.

Once upon a time, Sheffield’s rivers teemed with fish. Apprentices in the mid-18th century got so bored eating salmon for lunch every day that they complained. Then industrialisation and a population boom did for the salmon and everything else living in the Sheaf.

Thankfully, that dismal story now has a plot twist. The nearby River Don, which the Sheaf joins less than a mile away, is springing back to life. Last year, researchers discovered salmon parr in the Don – young fish readying themselves for migration out to sea – the first evidence of breeding in over 200 years. Perhaps one day salmon will return to the Sheaf as well. There is at least light now in this darkest of tunnels.