Pollution, Trout in Dirty Places, Urban rivers, Wandle

River on a knife edge

This time last year when I wrote in my introduction to Trout in Dirty Places

Despite their recovery and fragile resilence, we shouldn’t be in any doubt that urban trout and grayling still inhabit rivers on a knife edge. Chances are, between the time I finish writing this book and you start reading it, at least one of the fisheries I’ve selected as a snapshot of urban river restoration at the start of the twenty-first century will have been wiped out by pollution…

… I knew it was technically possible that one of those rivers would be the Wandle.

Technically possible, yes, but surely not likely?

Turns out I was wrong.

Last Tuesday night, a fire that raged uncontrollably through Beddington sewage treatment works’ power house and control room resulted in a spill of sludge and partially treated sewage into the river while emergency teams from Thames Water and the Environment Agency laboured frantically to switch the works over to manual operation with diesel generators powering each process.

“It’s like restarting a 747 from cold”, one of my Thames Water contacts told me. “We’ll get it up again, but it’ll take a while.”

In the meantime, the works’ storm tanks had filled, and the constant inflow of south London’s sewage had lifted the sludge cap off the final treatment tanks and pushed it into the Wandle.

Despite aeration pumps and 70 tonnes of hydrogen peroxide stockpiled on Mill Green, the EA estimated that hundreds of fish died: not a full-scale clean-like-your-bathroom-floor wipeout like the notorious bleach spill of 2007, but enough for disbelief and a jaw-dropping sense of surely not again?

These past 3 days and nights, the Wandle Trust’s staff and trustees have been running triage: manning the phones, moderating blog comments, measuring dissolved oxygen levels, and helping EA fisheries teams to net 11 species of dead fish out of the river whilst still making sure ongoing projects get delivered.

Post mortems will come next… but for now it turns out living with a sewage treatment works that serves a large proportion of a global city and provides up to 80% of your river’s flow is like making your home under the shadow of an active volcano: you don’t know for sure when it’ll go off next, but you know beyond doubt that it will, and you’ve just got to make certain all your systems are strong and resilient enough to cope.

So that’s what we’ll carry on doing.