Urbantrout Diaries 7: A Year of Mending Urban Rivers: Part 1
Theo Pike is back with a three-part look at some river restoration and conservation projects.
In the UK’s river-mending community, this summer feels like the one when it all finally kicked into high gear.
Years of planning and detailed funding applications to the Heritage Lottery Fund or European adaptive land use projects (and in other cases high-speed scrambles for Defra’s Catchment Restoration Fund and Catchment Partnership Fund) have metamorphosed into full-on river reconstruction programmes as widely dispersed as Norfolk’s ‘9 Chalk Rivers’ and the Eden’s Leith and Lyvennet tributaries. And, as you’d surely hope, many urban rivers have been getting in on this action too.
Here on my own home water in south London, two stretches of the upper Wandle have been utterly transformed. That’s no exaggeration: at Butter Hill and Hackbridge, where low, slow, impounded flows have spent the last couple of centuries dropping thigh-deep, evil-looking silt behind industrial and ornamental weirs, we’ve now got chattering riffles, long tongues of current snaking down gravelly pools, and backwaters to shelter fish fry of all species when big spates come down from Carshalton and Croydon.
Just across the road, where I used to dread wading after bikes and shopping trolleys into sucking ooze that belched bubbles of methane and the clinging stench of motor oil, it’s now possible to hear the river before you can even see it: cold chalk water let loose down its natural gradient again, gushing through the branches of a tree we’ve staked into the gravels and current, saturating the river with oxygen year-round and restoring a fugue of living water to the soundscape of this south London street.
All this has been made possible by cutting a three-foot notch into the old mill weir to reset a pre-existing (but not-quite-functioning) Larinier fish pass. And now the Wandle’s big trout should be able to get past this old industrial site to spawn below Carshalton Ponds for the first time since Domesday Book was compiled.
Downstream at Hackbridge, our big surprise was finding most of the original gravels of the old ford and river bed still there – buried under a hundred years of silt and road runoff, but never dredged out wholesale for road building or flood defence as we’d feared. Until the diatoms got going, covering the stones with the Wandle’s familiar dark biofilm that makes sight-fishing so difficult, the flint’s natural colours gave the clear water an extraordinary blue tint. If you focused on the bigger cobbles and cropped out some of the urban background, it was hard to believe you weren’t looking at a stretch of a white-limestone mountain river like the Soca or Sava.
When you’re removing urban weirs and regrading the river through that head loss, one of the biggest potential costs of river restoration is dealing with all those tonnes of sediment – potentially contaminated with lead, hydrocarbons and nameless residues from past industrial processes. It’s hugely expensive to dump into landfill, so recycling it into the reconstructed river’s profile makes much better sense: first defining a tighter, meandering bank line with stakes and brash bundles, then using excavators to scoop the silt behind the brash, and trapping it permanently in an envelope of biodegradable coconut matting overlaid with gravel.
Then, after the heavy machinery is out of the river, you can send in the volunteers. Over three weekends we dug almost ten thousand native plants into the new river banks, zoning different species in separate clumps to stop the more vigorous plants out-competing slower growers. Already, as I’m writing this, the root structures of flag iris, purple loosestrife, hemp agrimony and ragged robin are boring down into those silt envelopes to creating a resilient, natural vegetation structure along the wet margins: next summer, starwort, ranunculus, wild mint and watercress will colonise from upstream, and there’ll be drier meadow areas further up the banks.
While all this good stuff has been happening on the Wandle, there’s been plenty of other wet work taking place in Burnley, Manchester, Sheffield, Sleaford and Wincanton – which we’ll visit in the next two parts of this article.
God’s not creating rivers any more, as someone said to me recently, but it looks like we’re getting a pretty good chance to re-do the job for Him…
Next time: How this year’s Wild Trout Trust Conservation Awards reflect a radical new era in river restoration
All images used are courtesy of the Wandle Trust
ABOUT THE AUTHOR
Theo is a freelance marketing, fly-fishing and environmental writer. He’s also Chairman of Trustees of the Wandle Trust, and founding editor of Urbantrout.net a website and eco-brand dedicated to urban fly-fishing and river restoration improvements.
Theo’s trailblazing book Trout in Dirty Places: 50 rivers to fly-fish for trout and grayling in the UK’s town and city centres was published in 2012. His second book, The Pocket Guide to Balsam Bashing – and how to tackle other Invasive Non-Native Species, was published by Merlin Unwin Books in May 2014.
Articles by the same author
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- Urbantrout Diaries 9: A Year of Mending Urban Rivers: Part 3
- Urbantrout Diaries 8: A Year of Mending Urban Rivers: Part 2
- Urbantrout Diaries 7: A Year of Mending Urban Rivers: Part 1
- Urbantrout Diaries 6: Taking the Fight to Invasive Non-native Species
- Urbantrout Diaries 5: Wet Weather in Wincanton
- Urbantrout Diaries 4: Spawning Time
- Urbantrout Diaries 3: Discovering the Dour
- The Urbantrout Diaries 2: Bashing Balsam
- The Urbantrout Diaries: Spinners in South London