A River Runs Through It


The Zoological Society of London is on the lookout for citizen scientists to help prevent river pollution, with a training event in Woodford Green this March. Conservation biologist Phoebe Shaw Stewart reports

Throughout March, intrepid urban explorers will be making their way along the banks of the River Roding in search of some unusual sightings. Local citizen scientists will be trained to search, not for lions or elephants, but for the telltale signs of polluting outfalls as part of conservation charity Zoological Society of London’s (ZSL) Outfall Safari programme.

Despite the fact this doesn’t sound quite as exciting as searching for the African big five, heterogenous slime (sewage fungus), food waste, sanitary ‘rag’ or discolouration of water and foam are the slightly less glamorous ‘big five’ of outfall safaris we look out for.

Outfalls are discharge points for water systems into nearby rivers or seas, but all too often, pipes from washing machines and sewage systems carrying wastewater are misconnected. This results in untreated wastewater entering rivers through surface water outfalls. Surface water outfalls are typically only made up of things like excess rainwater that runs off your drive and into the drains, but largely doesn’t need to be treated. Herein lies the problem, with the crossover wreaking havoc with wildlife.

In London alone, it’s estimated that around 3% of all properties suffer from misconnected pipes, with new kitchen extensions often being the main perpetrator with poorly connected washing machines, kitchen sinks and hand basins, according to Thames Water. The misconnections are one of the core reasons urban rivers are unable to reach ‘good ecological potential’ under the EU Water Framework Directive. Large pollution events can quickly deplete water of oxygen and lead to elevated phosphate and ammonia levels. This can cause local wildlife, such as the 126 known fish species recorded in the Thames, and their habitats to become at risk.

ZSL’s Outfall Safari helps to combat this issue by training citizen scientists across London to identify these misconnections. The data is then highlighted to Thames Water, who fund the project, and the Environment Agency through an app to help tackle the issue. They’re also illegal, so once identified, they must be rectified. The method was first used on the River Crane in west London, and since then, has been carried out on over 250km of rivers within Greater London. So far, data shows an average of more than two pollution outfalls identified per kilometre of river surveyed.

ZSL is always looking for new volunteers to help identify misconnections to protect local wildlife. So, please do sign up if you would like to be involved.

An Outfall Safari training session will take place at the James Leal Centre in Ray Park, Woodford Green in partnership with Vision RCL on 4 March from 1.30pm to 3.30pm – visit swvg.co.uk/os. For more information about ZSL’s work in the Thames, visit swvg.co.uk/zsl