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Fish killed in the River Lea. Pushed to their limits by environmental mismanagement

Fish were killed in numbers on Tuesday July 23 by Oxygen depletion of the River Lee downstream of Deephams sewage works in Tottenham. Climate change has created the conditions for an exceptional heatwave to become a more frequent possibility.

The amount of water extracted upstream for human use is considerable. Downstream about 50%-80% of the water body can be treated sewage. During the dry summer months there often isn't enough water-flow to provide reliable conditions for the fish. The amount of dissolved Oxygen in the water in a rain free heatwave can become so depleted that fish begin to suffer.

The description of an English Summer as 'two fine days and a thunderstorm' was enacted grossly by the first tropical thunderstorm I have ever seen exploding over London overnight. Its deluge over the River Lee catchment area was probably somewhat less than it might have been given the power of its vast electrical display. The exceptional runoff from the city's streets and hard parched open spaces poured into the sewage pipework. Deephams treatment plant over 50 times a year discharges raw sewage into the River Lee when more than 2mm of rain per day falls on our capital city. This happens because the expansion of waste water production from London has long since exceeded even the augmented capacity of the original Victorian system.

The long heatwave had reduced the stored Oxygen amount in the river water especially in slower moving sections like the Lee Navigation. The sudden deluge of polluted water into the River dramatically pushes up the volume, the flow rate, the biological load of toxins and changes the temperature of the water. The fish experience a rapid depletion of the Oxygen content of their living medium. The Environment Agency anticipated and responded to this event by pouring Hydrogen Peroxide into the Lee Navigation near Springfield Marina and just upstream of Prescott/Three Mills Lock. This releases extra Oxygen into the water. Such action appears to have somewhat reduced the potential fish kill.

 Yesterday in the Lee Navigation Photo: Charlie CharmanYesterday in the Lee Navigation Photo: Charlie Charman

The river's fish populations have over recent decades experienced huge adverse changes in the viability of their environment due to long under-investment in the quality of the water and the infrastructure of the river Lee system. British Waterways were the institution responsible for the upkeep of the River Lee. They were a statutory corporation, wholly owned by the government, responsible as the navigation authority for the majority of canals and a number of rivers and docks in Britain. Despite the huge rise in leisure boating on our canals and waterways and the great enthusiasm for voluntary restoration and upkeep work on the system, British Waterways have long been run with a multimillion pound defecit. This and increasing removal of government subsidies has pushed them into becoming a developer of waterside property seeking large returns to the detriment of their management of the waterways.

This led them into fronting the Prescott Channel scam. They colluded with the government, the GLA, the London Borough of Newham, Thames Water, the Olympic Delivery Authority and others in the promotion of a false prospectus for the construction of a 350 ton barge handling lock and barrage whose prime function, at vastly wasteful expense, was to impound the tidal Old River Lee. This changed some of the four mile stretch from Lee Bridge to Prescott Lock (renamed as Three Mills Lock, No. 2012 [geddit?] ) to a controlled navigable waterway. Thus abruptly changing the ecology of this important habitat to create a key development in the Water City initiative. British Waterways changed their constitution a year ago and are now called the Canal and River Trust.

The Olympics developments were awarded sustainability prizes for the greenest games ever yet were criticised by the Commission for a Sustainable London 2012 for the patchiness of their sustainable outcomes. They achieved these outcomes by framing their chosen boundaries within which sustainability was assessed. Invisible 'externalities' like pollution from dust and noise, illegal disposal of radioactive soil, inadequate restitution of dispersed communities, crude removal of impediments to nonsensical schemes, were all omitted from the sustainability review.

So why does this fish kill matter? From a stretch of river no longer fished by keen anglers, from which European Cormorants still fish occasionally for the few remaining small fish, from which criminals from Eastern Europe illegally net the greatly diminished shoals of Common Bream when they assemble to spawn in Spring, whose residual fish population's welfare is ignored by the land-grab developers who swarm eagerly in pursuit of profits around the Olympics project. It matters because it stands for our urban condition which we frantically maintain at a faster and more tightly co-ordinated and stressed state near breakdown. That thunderstorm was a product of a rapacious and polluting industrial system combining with our climate which is shifting against us with increasingly unpredictable volatility. Neoliberal privatising capitalism is going for the burn to be faster, more brutal, more fragmented and chaotic. If the fish got lucky this time because the deluge was not that great, if the Environment Authority Oxygenators pulled the fish kill back from a greater disaster, if the most sensitive creatures in our local system can go back to barely coping, how soon will there be a next time when it all starts to unravel big time. When our luck runs out again and again and again.

See also: Journey Along the River Lee, Leo Hickman, The Guardian

And also: Thames 21 A Healthier Future for East London's Rivers - three big solutions

My thanks to Nick Atkins for alerting me ahead of this fish kill episode of its likelihood.

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